ALBERT

Beschreibung: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 456〈/p〉 〈p〉Author(s): Satoshi Abo, Albert Seidl, Fujio Wakaya, Mikio Takai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An effect of sample bias voltage on analysis time and time resolution of a single-event three-dimensional time-of-flight (ToF) Rutherford backscattering spectrometry (RBS) was evaluated with both experiment and simulation. Fluctuations of trajectories of secondary electrons were suppressed by positive sample bias voltage and most of the secondary electrons were collected by a secondary electron detector, resulting in short analysis-time and high time-resolution in the single-event three-dimensional ToF-RBS. On the contrary, negative sample bias voltage induced tertiary electrons at a focused ion beam (FIB) column by incident of the secondary electrons which accelerated by an electric field between the sample and the FIB column. The tertiary electrons improve analysis time, but deteriorate time resolution in the single-event three-dimensional ToF-RBS with negative sample bias voltage.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 458〈/p〉 〈p〉Author(s): F. Tárkányi, A. Hermanne, F. Ditrói, S. Takács, A.V. Ignatyuk〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the frame of a thorough investigation of activation cross sections of deuteron induced nuclear reactions, excitation functions on iridium were investigated up to 50 MeV deuteron energy. Production cross sections were measured for the 〈sup〉193m〈/sup〉Pt, 〈sup〉191〈/sup〉Pt, 〈sup〉189〈/sup〉Pt, 〈sup〉188〈/sup〉Pt, 〈sup〉187〈/sup〉Pt, 〈sup〉194m2〈/sup〉Ir, 〈sup〉194g〈/sup〉Ir(m1 + ), 〈sup〉192g〈/sup〉Ir(m1 + ), 〈sup〉190m2〈/sup〉Ir, 〈sup〉190g〈/sup〉Ir(m1 + ), 〈sup〉189〈/sup〉Ir, 〈sup〉188〈/sup〉Ir, 〈sup〉187〈/sup〉Ir and 〈sup〉191g〈/sup〉Os(m1 + ) radionuclides. Activation method, stacked foil irradiation technique and off-line gamma-ray spectrometry were used for quantification of the radionuclides. The experimental results are compared with earlier data in the overlapping energy range. We discuss theoretical predictions obtained from the ALICE-IPPE-D and EMPIRE-II-D codes. The experimental data are also compared with calculated values reported in the TENDL-2017 on-line library calculated by using the TALYS code.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 458〈/p〉 〈p〉Author(s): Hongtao Shen, Kimikazu Sasa, Qi Meng, Masumi Matsumura, Tetsuya Matsunaka, Seiji Hosoya, Tsutomu Takahashi, Maki Honda, Keisuke Sueki, Lisha Chen, Huijin Lu, Ming He, Baojian Huang, Yongfu Qin, Jiahao Li, Haihui Lan, Zhaomei Li, Zhenchi Zhao, Mingji Liu, Siyu Wei〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Tiankeng, a typical Karst relief of the Late Quaternary Period, in the south of China, plays an important role when researching the surface shape and evolution of the Karst relief. The accumulation of Chlorine-36 (T〈sub〉1/2〈/sub〉 = 301 ka) through the interaction of cosmic ray particles with Ca, K and Cl in rocks allow it to be used as the ideal nuclide for determination of the exposure age and erosion rate of limestone. In this work, an improved 〈sup〉36〈/sup〉Cl sample preparation method for Tiankeng limestone was presented. The Isotope Dilution-AMS technique allows for the simultaneous measurement of 〈sup〉36〈/sup〉Cl and Cl with a single AMS sample preparation. The barium introduced during the sample preparation was removed to avoid ionizer poisoning and attain a higher and more stable beam current. The method is particularly suitable for limestone samples, as well as for soil, sediment and water samples.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 458〈/p〉 〈p〉Author(s): Jaroslav Červenák, Ondřej Lebeda〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We measured cross-sections of the nuclear reactions 〈sup〉197〈/sup〉Au(p,x)〈sup〉197m〈/sup〉Hg, 〈sup〉197g〈/sup〉Hg, 〈sup〉195m〈/sup〉Hg, 〈sup〉195g〈/sup〉Hg, 〈sup〉196m2〈/sup〉Au, 〈sup〉196m1+g〈/sup〉Au, 〈sup〉194m+g〈/sup〉Au in the energy range of 6.4–35.3 MeV having used stacked-foil technique with high purity gold foils. The results were compared with previously published data and with prediction of the TALYS nuclear reaction model code adopted from the TENDL-2017 library. Thick target yields were deduced from the measured data. Production of the theranostic isomeric pair 〈sup〉197m,g〈/sup〉Hg is thoroughly discussed.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 458〈/p〉 〈p〉Author(s): Zi-Qi Wang, Yu-Hao Li, Zhong-Zhu Li, Hong-Bo Zhou, Guang-Hong Lu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉By performing the first-principles calculations, we explore the dissolution and diffusion of hydrogen (H) in hexagonal closed packed zirconium (Zr) as well as its interaction with vacancy. We show that the tetrahedral (TE) interstitial site is the favorable trapping site for a single H atom with the solution energy of −0.45 eV. Such a negative solution energy is due to the strong electronic bond between H and neighboring Zr atoms. Moreover, the energy barrier for the migration of H from a TE site to its 1NN and 2NN TE site is 0.12 eV and 0.42 eV, respectively. It is noteworthy that the first path only slightly contributes to the experimentally measured H diffusivity in Zr, because the H atom is trapped by two nearest neighboring TE sites. Thus, the effective activation energy for H diffusion in Zr should be mainly determined by the second path, and the corresponding energy barrier is 0.42 eV. Furthermore, since the electronic density (available volume) in vacancy is lower (larger) than that of interstitial site, vacancy is a strong trap for H atoms in Zr. We demonstrate that the maximum of 8 H atoms can be accommodated in a mono-vacancy without the observation of H〈sub〉2〈/sub〉 molecule. These results can provide a basis to develop Zr materials in nuclear cladding devices.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 31 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): David D. Cohen, Armand Atanacio, Jagoda Crawford, Rainer Siegele〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Fine particle air pollution is a significant problem in large urbanised areas across the Asian region. With funding from the International Atomic Energy Agency (IAEA) fifteen countries in Asia have been collecting weekly samples on filters of fine and coarse particles in major cities for the past 15 years. These filters have been analysed for over 20 different chemical species from hydrogen to lead using a range of analytical techniques including accelerator based ion beam techniques such as PIXE, PIGE, PESA, RBS, as well as XRF and NAA. These data have been included into a major database, which is generally available, containing over 17,000 combined sampling days from these fifteen countries spanning an area of the globe from ± 50° latitude and from 70° to 180° longitude. That is, the sampling covers an area north-south from Mongolia to New Zealand and west-east from Islamabad, Pakistan to Wellington, NZ.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 458〈/p〉 〈p〉Author(s): Ş. Kaya-Keleş, G.S. Polymeris, N. Meriç〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the present work, pre-dosed α-quartz is investigated towards its effective applications in retrospective dosimetry and dating as a reference material. The purpose of the study is to find tentative correlations between Thermoluminescence (TL) (high temperature TL (HTTL) peaks), Optically Stimulated Luminescence (OSL) (both continuous wave (CW) and linear modulated (LM)) and Electron Paramagnetic Resonance (EPR). The present work indicates a triple correlation between the fast CW-OSL component and certain peaks of LM-OSL and TL signals, while all these luminescence entities are attributed to the EPR signal with 〈em〉g〈/em〉-value (Landé splitting factor) at 1.9975 called C2〈sub〉EPR〈/sub〉. The present study provides experimental evidence that (i) one TL peak might be the source for more than two LM-OSL components and (ii) even two different TL peaks can contribute to the same OSL component. Furthermore, on the EPR signal, besides the well established Ge center, another un-identified component has been resolved.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 458〈/p〉 〈p〉Author(s): S. Akça, Z.G. Portakal, T. Dogan, N. Kucuk, A. Canimoglu, M. Topaksu, N. Can〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, we performed Thermoluminescence (TL) experiments to extract the trapping parameters and dosimetric properties of Tb-doped Mg〈sub〉2〈/sub〉SiO〈sub〉4〈/sub〉 phosphors. Glow peaks located at 193, 270, and 350 °C were observed in the glow curve but the peak at 193 °C was especially investigated as a dosimetric peak in this study. We also observed an anomalous heating rate effect in which the maximum TL intensity of the glow curve augmented with an increasing heating rate. The computerized glow curve deconvolution (CGCD) method, initial rise (IR) and Hoogenstraaten’s method were used to determine the activation energies of associated trapping centers for both BSL-TL 365 nm and IRSL-TL wideband blue filters. The TL characteristics of this phosphor indicate that Mg〈sub〉2〈/sub〉SiO〈sub〉4〈/sub〉:Tb〈sup〉3+〈/sup〉 could be a promising material for dosimetric applications. Efforts should be made to improve the fading behaviour by adding other activators as co-dopants.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 458〈/p〉 〈p〉Author(s): S.D. Liu, N. Stolterfoht, Y.T. Zhao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Simulations of a 1-MeV proton microbeam transmitted through an insulating macrocapillary were conducted to gather a detailed insight into the related guiding mechanisms. The calculations were performed in view of previous experiments showing guided transmission for a proton beam with a diameter of 2 μm. The simulations are in agreement with the previous results using a microbeam with a divergence of 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si11.svg"〉〈mrow〉〈mn〉0.6〈/mn〉〈mi〉°〈/mi〉〈/mrow〉〈/math〉, for which guided transmission was observed. This guiding is attributed to the generation of an extended charge patch, producing a broad deflection field along the capillary length. On the other hand, it is found that the transmission of the microbeam without divergence is impossible showing that the divergence plays a decisive role in the guiding process. Further results provide clear evidence that guiding can occur for usual MeV proton beams rather than only for a microbeam.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 3 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): E.I. Obiajunwa, G.A. Osinkolu, F.I. Ibitoye, D.A. Pelemo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The Centre for Energy Research and Development (CERD), Obafemi Awolowo University, Ile-Ife, Nigeria, acquired a NEC 1.7 MV Tandem Pelletron accelerator with one beamline in 2008 for ion beam experiments. This was upgraded in 2014, with the addition of a second beamline equipped with NEC RC 43 end station. This paper presents an overview of the accelerator, its capabilities, and its applications in research.〈/p〉 〈p〉A full description of the first end-station designed and built at iThemba Labs, South Africa, is also presented. A number of PIXE and RBS experiments have been carried out using this facility and the results are also presented. This paper further discusses the diverse areas of application of the accelerator, including solid minerals/geology, biomedical samples, materials science, environmental pollution, and agriculture.〈/p〉 〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 458〈/p〉 〈p〉Author(s): T. Murata, M. Aikawa, M. Saito, H. Haba, Y. Komori, N. Ukon, S. Takács, F. Ditrói〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An experiment of 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si72.svg"〉〈mrow〉〈mi〉α〈/mi〉〈/mrow〉〈/math〉-induced reactions on yttrium-89 was performed to investigate the excitation functions of 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si73.svg"〉〈mrow〉〈msup〉〈mrow〉〈/mrow〉〈mrow〉〈mn〉89〈/mn〉〈/mrow〉〈/msup〉〈mtext〉Zr〈/mtext〉〈/mrow〉〈/math〉 and 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si74.svg"〉〈mrow〉〈msup〉〈mrow〉〈/mrow〉〈mrow〉〈mn〉90〈/mn〉〈/mrow〉〈/msup〉〈mtext〉Nb〈/mtext〉〈/mrow〉〈/math〉, which are suitable for immuno-PET studies. The stacked-foil method, activation technique, and off-line 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si75.svg"〉〈mrow〉〈mi〉γ〈/mi〉〈/mrow〉〈/math〉-ray spectrometry were used for this investigation. The excitation functions of 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si76.svg"〉〈mrow〉〈msup〉〈mrow〉〈/mrow〉〈mrow〉〈mn〉92〈/mn〉〈mi mathvariant="normal"〉m〈/mi〉〈mo〉,〈/mo〉〈mn〉91〈/mn〉〈mi mathvariant="normal"〉m〈/mi〉〈mo〉,〈/mo〉〈mn〉89〈/mn〉〈mi mathvariant="normal"〉m〈/mi〉〈mo〉,〈/mo〉〈mn〉89〈/mn〉〈mi mathvariant="normal"〉g〈/mi〉〈/mrow〉〈/msup〉〈mtext〉Nb〈/mtext〉〈mo〉,〈/mo〉〈msup〉〈mrow〉〈/mrow〉〈mrow〉〈mn〉88〈/mn〉〈/mrow〉〈/msup〉〈mtext〉Zr〈/mtext〉〈/mrow〉〈/math〉, and 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si77.svg"〉〈mrow〉〈msup〉〈mrow〉〈/mrow〉〈mrow〉〈mn〉90〈/mn〉〈mi mathvariant="normal"〉m〈/mi〉〈mo〉,〈/mo〉〈mn〉88〈/mn〉〈mi mathvariant="normal"〉g〈/mi〉〈mo〉,〈/mo〉〈mn〉87〈/mn〉〈mi mathvariant="normal"〉m〈/mi〉〈mo〉,〈/mo〉〈mn〉87〈/mn〉〈mi mathvariant="normal"〉g〈/mi〉〈/mrow〉〈/msup〉〈mtext〉Y〈/mtext〉〈/mrow〉〈/math〉 were also derived and compared with earlier experimental and the TENDL-2017 data. Good agreements with part of the previous studies were found.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 458〈/p〉 〈p〉Author(s): Zeljko Pastuovic, Jeremy Davis, Thuy Linh Tran, Jason R. Paino, Andrew Dipuglia, Benjamin James, Marco Povoli, Angela Kok, Vladimir L. Perevertaylo, Rainer Siegele, Dale Prokopovich, Michael Lerch, Marco Petasecca, Anatoly Rosenfeld, David D. Cohen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ion Beam Induced Charge (IBIC) microscopy performed using highly tuned microbeams of accelerated ions with energies in the MeV range is the powerful tool for analysis of charge carrier transport properties in semiconductor devices based on semiconductor hetero-junction, metal-on-semiconductor and semiconductor-on-insulator configurations. Here we present two cases of recent applications of the IBIC microscopy in the field of medical radiation physics. The reduced-rate ion microbeams with energies in the MeV range and sub-micrometer spot-sizes have been used for the investigations of the charge collection efficiency (CCE) in sensitive volumes of segmented radiation detectors in order to measure the spatial distribution and uniformity of CCE in different polarization conditions. This information allows the determination of the charge carrier transport properties in selected substructures of a particular device and to quantify its ability to accurately determine the energy deposited by incident ionizing radiation - two fundamental requirements of any microdosimeter or detector of ionizing radiation.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 457〈/p〉 〈p〉Author(s): 〈/p〉

Beschreibung: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 458〈/p〉 〈p〉Author(s): Peter Steier, Karin Hain, Urs Klötzli, Johannes Lachner, Alfred Priller, Stephan Winkler, Robin Golser〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Interest in the long-lived radioisotope 〈sup〉236〈/sup〉U (T〈sub〉1/2〈/sub〉 = 23.4 million years) has significantly increased recently due to the emergence of environmental and earth science applications. Compared to the previous setup at VERA, which was based on oxygen stripping and a time-of-flight detector, we have improved the sensitivity of VERA by more than an order of magnitude by switching to helium stripping and by installing a second 90° magnet in our analyzer beamline. The new setup has been successfully employed for several research projects.〈/p〉 〈p〉Here, we present the characterization of the upgraded spectrometer. We discuss the design of the new beamline and present benchmark measurements, suggesting an instrumental sensitivity limit well below 〈sup〉236〈/sup〉U/〈sup〉238〈/sup〉U = 10〈sup〉−14〈/sup〉. The yield for the 3+ charge state is 19%, of which 90% are recorded in the detector. In environmental samples, one in 4500 sputtered actinide atoms is detected. While this allows tackling natural 〈sup〉236〈/sup〉U, also measurements of anthropogenic 〈sup〉236〈/sup〉U or other actinides profit from the higher sensitivity. This allows analysis of smaller samples, but also has made the rare anthropogenic isotope 〈sup〉233〈/sup〉U accessible.〈/p〉 〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 458〈/p〉 〈p〉Author(s): 〈/p〉

Beschreibung: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 458〈/p〉 〈p〉Author(s): Oleksandr V. Romanenko, Alexander G. Ponomarev, Anna Macková, Vladimír Havránek, Artem Ponomarov〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ion scanning microprobe was implemented in the Tandetron Laboratory, Nuclear Physics Institute of the Czech Academy of Sciences (NPI CAS) in Rez in 2009. Since then it has been involved in numerous experiments for investigation and modification of the materials where PIXE, PIGE, RBS and STIM are the main analytical methods. Rez microprobe is coupled with a tandetron accelerator, which provides ions from hydrogen to gold, and able to focus heavy ions with the maximum mass energy product at the level 11 MeV amu/q〈sup〉2〈/sup〉. Therefore, microprobe can be used for polymers irradiation by protons and helium as well as for irradiation of various types of glass and other materials with heavy ions. The number of applications for the microprobe in the Tandetron Laboratory is constantly increasing; that leads to the necessity to raise the efficiency of the microprobe operation. Increasing the beam current density allows for a reduction in the time per experiment in relation to recording the number of events. The present work is an attempt to improve the parameters of existing ion scanning microprobe based on a compact Oxford triplet lens system. Since the microprobe is used to investigate both thin and thick targets, the position of the detectors that can restrict the microprobe construction were taken into account in the calculation. The collimated acceptance of the probe-forming system was selected as an objective function as it takes into account both chromatic and all spherical aberrations. Two methods for improving the microprobe parameters were considered. The first one is based on separation of the first lens in the system, whilst the second – on decreasing the working distance. Both ways need changing in the microprobe construction, but the last one requires a major alteration in a target chamber. The benefits of each way were studied. Obtained parameters of the new probe-forming system have shown a two fold increase of the current density of the given probe size for Rez microprobe in comparison with the present system. The benefits of the displacement of the first lens disappear with the decreasing of the working distance.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 458〈/p〉 〈p〉Author(s): S.A. Mahdipour, B. Azadegan, A.A. Mowlavi, M. Shafeei, W. Wagner〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The non-conventional (hybrid) scheme of a positron source using GeV electron beams is investigated by means of our Mathematica and GEANT4 simulation codes. Axial channeling radiation (CR) is generated in a Si single crystal (radiator) and subsequently converted into e〈sup〉+〈/sup〉–e〈sup〉−〈/sup〉 pairs in an amorphous tungsten (W) target (converter).〈/p〉 〈p〉We will present numerical calculations of axial CR spectra from relativistic electrons of different energies channeled in a Si single crystal. Applying both the dipole and non-dipole approach, comparison reveals a striking difference between obtained energy distributions of axial CR.〈/p〉 〈p〉Positron spectra obtained by pair production and captured by an adiabatic matching device (AMD) are simulated using GEANT4 toolkit. The AMD provides an axial magnetic field of upstream decreasing strength between the converter and the aperture of some pre-accelerating structure (linac). We also present Monte-Carlo simulation results of positron-beam emittance and transverse beam-density distribution behind the W converter and behind the AMD.〈/p〉 〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 458〈/p〉 〈p〉Author(s): Jian Yin, Yi Wang, Huaiyu Hou, Jing Tao Wang, Xiangbing Liu, Fei Xue〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work the interactions of an edge dislocation with Cu precipitates of different diameters in α-Fe were investigated by molecular dynamics simulation. The influence of Fe atoms or outer Ni shell on the interactions was also studied. It is found that the dislocation stress field assists a structure transformation of the precipitates from BCC to FCC/HCP during the gliding of the dislocation. For the Cu precipitates with diameters less than 4 nm, most of the atoms return to BCC structure after the dislocation leaves away. The structure transformation of Cu-Fe precipitates is identical with pure Cu precipitates with diameters less than 4 nm. The outer Ni shells contribute the precipitate transformation to FCC/HCP structure and reduce the critical diameter of structure transformation. The critical resolved shear stress (CRSS) has been calculated for the precipitates and it is demonstrated that the FCC/HCP fraction of the precipitate contributes to the CRSS in this interaction.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 458〈/p〉 〈p〉Author(s): M.M. Mikhailov, S.A. Yuryev, A.N. Lapin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The authors propose a model for the physical processes that occur under ionizing irradiation in BaSO〈sub〉4〈/sub〉 powders modified with SiO〈sub〉2〈/sub〉, Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉, and ZrO〈sub〉2〈/sub〉 nanoparticles. The model is based on physical representation and on the experimentally obtained correlation between spectra, solar absorptance, nanoparticle concentration, and accelerated electron fluence. The model includes four constituents, two of which describe accumulation of defects solely for initial irradiated powders. In case of irradiated BaSO〈sub〉4〈/sub〉 powders, accumulation processes are described via all constituents. The changes in optical properties have been predicted and calculated under electron spectra exposure at the geostationary orbit within 15 years period.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 458〈/p〉 〈p〉Author(s): Simone Manenti, Ferid Haddad, Flavia Groppi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We investigated 〈sup〉89〈/sup〉Zr production induced by deuteron beams on yttrium targets at energies up to 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si6.svg"〉〈mrow〉〈msub〉〈mrow〉〈mtext〉E〈/mtext〉〈/mrow〉〈mrow〉〈mi〉d〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 = 32 MeV using the stacked-foil activation technique. Cross sections of the following nuclear reactions 〈sup〉89〈/sup〉Y(d,2n)〈sup〉89〈/sup〉Zr, 〈sup〉89〈/sup〉Y(d,3n)〈sup〉88〈/sup〉Zr and 〈sup〉89〈/sup〉Y(d,x)〈sup〉88〈/sup〉Y have also been measured. Based on the measured values, we determined the thick target yields for 〈sup〉89〈/sup〉Zr and 〈sup〉88〈/sup〉Zr which is the main contaminant associated to the production of 〈sup〉89〈/sup〉Zr.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 458〈/p〉 〈p〉Author(s): Kengo Moribayashi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To understand the physical phenomena caused by heavy ion irradiation, we propose a radial dose simulation model, which is closer to reality than conventional models, and is independent of (without specifying) the species of incident ions. With the aim of disseminating our radial dose simulation results for use in radiology and radiation biology, we create a function to fit these results. Using this fitting function, anyone can calculate the radial dose distributions, which almost reproduce our simulation results, within a few seconds. In this function, incident ion energies up to ∼100 MeV/u and a stopping power up to ∼600 keV/μm are covered. Furthermore, using this model, we discuss the incident ion energy dependence on the radial dose, according to incident ion impact ionization cross-sections.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 5 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): J-O. Lill, V. Finnäs, Y. Heimbrand, M. Blass, S. Fröjdö, Y. Lahaye, J.M.K. Slotte, J. Nyman, E. Jokikokko, M. von Numers, H. Hägerstrand〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The elemental composition of otoliths provides historical information on migration and provenance of fish. Due to the complex structure of the otoliths, the depth from which the elemental information originates has to be considered. In this work, three analytical methods often used to assess otolith chemistry are compared. The information depths are calculated for µ-XRF and PIXE and measured for LA-ICP-MS. The information depth in PIXE depends on the energy of the incident particles and on the element to be analysed while in XRF it depends mostly on the element to be analysed as the energy of the incident X-rays usually is high enough to excite atoms at depths of several hundreds of micrometres. If we assume that the otolith is exposed to X-rays from a Rh-tube (20.16 keV) about 50% of the detectable Sr(Kα) X-rays will be emitted from a depth ranging from 0 to 114 µm. In the case of PIXE with 3 MeV protons the corresponding range is 0–15 µm. The information depths in LA-ICP-MS were determined by measuring the depth of the laser-ablated craters or trenches that remained on the otolith surface. The depths measured with a scanning white light interferometer (SWLI) were found to be about 40 µm (spots) and 11 µm (trenches).〈/p〉 〈p〉The correlation between strontium concentrations obtained by spot analysis of whitefish otoliths with PIXE and LA-ICP-MS was excellent (92%), although different spot sizes were used. A comparison of strontium concentration profiles measured with µ-XRF and LA-ICP-MS showed that the higher information depth of µ-XRF in combination with the 52 degree angle of the incident X-rays smoothens out the sharp edges seen in the LA-ICP-MS profiles. Otoliths from whitefish captured in the Baltic Sea (n = 30) were analysed in this comparison of methods. Among these whitefish there are sea spawners, river spawners and stocked fish with different life history and different otolith chemistry.〈/p〉 〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 458〈/p〉 〈p〉Author(s): G.U.L. Nagy, I. Rajta, K. Tőkési〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We present theoretical investigation of the temporal evolution of the energy spectrum of ions passing through an insulating capillary. In our simulation we used 1 MeV proton microbeam, and a single, cylindrical shaped polytetrafluoroethylene (PTFE) macrocapillary. In order to prevent the simple geometrical transmission the beam axis was tilted with 1° compared to the capillary axis. According to our simulations, we found that the beam first hit the inner wall of the capillary and build a positive charge patch at a well localized place of the inner capillary surface. As a result, a repulsive electric field is generated for protons enter later into the capillary and a collision-less transmission occurs, which is called ion guiding. We show that our simulated energy spectra are in good agreement with our previous experimental findings.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 3 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): B. Cui, L. Chen, Y. Ma, R. Ma, X. Ma, B. Tang, Q. Huang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A prototype ion source for RIB production in a reactor has been developed at China Institute of Atomic Energy to demonstrate the feasibility. The ion source has to be compact enough to fit into the neutron tunnel of the reactor. Also the ion source has to withstand the tens of kW heat from target fission. An electric heater is used to simulate the fission heat; at the same time the cathode of the ion source is heated to emit electrons which are energized between anode and cathode to ionize the fission product. The details of the ion source and its preliminary test results will be presented.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 438〈/p〉 〈p〉Author(s): T. Kubley, F. Naab, O. Toader, G. Was〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Michigan Ion Beam Laboratory (MIBL) at the University of Michigan houses three electrostatic accelerators and six ion sources, providing beams to five target chambers and a TEM via nine distinct beamlines. Such a large system incorporates numerous control and monitoring instruments that can more easily be managed through a digital remote interface system. MIBL has implemented a variety of standard laboratory hardware and custom alternative hardware and software tools into a remote interface system that provides for greater laboratory efficiency, increased application flexibility and information flow and reduced cost. The outcome is that users can operate three accelerators and their corresponding beamline system from one console using a master control program, eliminating the need to constantly traverse the facility to monitor and manipulate instruments. Furthermore, the digitalization and centralization of the data generated by each subsystem has allowed for logging and variable correlation that would otherwise be impossible at such a large scale, and enabled the future application of modern tools such as machine learning to enhance operational efficiency.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 436〈/p〉 〈p〉Author(s): Juliette Colombani, Ahmedou Sidi, Jean-François Larché, Agnès Rivaton〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The effect of gamma-irradiation and temperature to accelerate, in a representative way, the ageing of EVA (Ethylene Vinyl Acetate)/EPDM (Ethylene Propylene Diene Monomer) blends was investigated. These blends constitute model materials of cable insulation used in Nuclear Power Plants (NPPs). Physicochemical evolutions of the blends were monitored by InfraRed (IR) spectroscopy, gel fraction measurements and Differential Scanning Calorimetry (DSC). After having pointed out the main similarities between the thermooxidative degradation (100 °C) and the radiooxidative degradation at room temperature, both stresses were combined to accelerate the ageing. It is shown that combining gamma-irradiation and high temperature, or subsequent thermooxidation after radiooxidation, accelerates the ageing but may cause distortion within the degradation mechanisms. These limitations of representativeness encountered are particularly due to an increase in chain scission reactions and formation of new crystallites in the blend.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 436〈/p〉 〈p〉Author(s): Anatoly Balagurov, Dmitry Balagurov, Ivan Bobrikov, Andrey Bogdzel, Vladimir Drozdov, Andrey Kirilov, Vladimir Kruglov, Sergey Kulikov, Svetlana Murashkevich, Valentin Prikhodko, Vasily Shvetsov, Valery Simkin, Alexander Sirotin, Nikolay Zernin, Valery Zhuravlev〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The High Resolution Fourier Diffractometer (HRFD) is a neutron time-of-flight spectrometer with a fast Fourier chopper and a correlation mode of data acquisition designed to study atomic and magnetic structures of crystalline materials with high resolution in reciprocal space. The HRFD was constructed in the early 1990s by a collaboration of JINR (Dubna), PNPI (Gatchina) and VTT (Espoo) and began operating routinely in 1994 at the IBR-2 pulsed reactor in Dubna. If correlation analysis is used, the HRFD Δ〈em〉d〈/em〉/〈em〉d〈/em〉 resolution is determined by the maximum rotational speed of the Fourier chopper. For 〈em〉V〈/em〉〈sub〉max〈/sub〉 = 6000 rpm, “high-resolution” patterns are measured by backscattering detectors with Δ〈em〉d〈/em〉/〈em〉d〈/em〉 ≈ 0.0015 despite a very short flight path (〈em〉L〈/em〉 ≈ 20 m) between chopper and sample. Switching to a regular TOF-mode (without Fourier chopper) makes HRFD one of the world’s best high-intensity diffractometers, capable of measuring diffraction patterns in the range of ∼1 min and less. In this paper, the experience of using HRFD at IBR-2 is considered and a possible solution for some technical and methodical problems of Fourier diffractometry at a long-pulse neutron source recognized during its operation is discussed. New possibilities appearing after the recent substantial HRFD upgrade and further perspectives on the method are also presented.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 436〈/p〉 〈p〉Author(s): Felix S. Olise, Adedamola D. Aladese, Chinonso E. Ugwumadu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉L-shell ionisation and x-ray production cross sections of trans-uranium elements: Np, Pu and Am, induced by protons of energies 5.00–20.00 MeV, have been calculated. The cross sections for the targets were obtained using computer codes based on the ECPSSR theory. Due to the lack of experimental data of the targets considered, in view of their radioactive, toxic and unstable nature, the calculated cross sections were subsequently validated. This was achieved using the computer codes to evaluate the ionisation and x-ray production cross sections of Uranium induced by protons of energies in the 1.00–20.00 MeV range. This study also showed that the relative x-ray line intensities associated with the ionisation and x-ray productions of the targets considered are dependent on protons energies.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 434〈/p〉 〈p〉Author(s): Shen Yang, Zuoxing Guo, Min Zhang, Qingfeng Guan, Yunxue Jin, Yuhua Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The microstructure and electrochemical behavior of zircaloy-4 prior and after high-current pulsed electron beam (HCPEB) irradiation were investigated. The microstructures of the surface layer were studied by means of X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Observation results indicated that, martensitic phase transformation was induced by HCPEB irradiation and formed plate martensitic structures containing a high density of ultrafine twins. When the number of pulse was increased, these structures were constantly refined along with their parent β grains. Besides, second-phase particles (SPPs) in the modified layers were completely dissolved into the substrate and formed Fe, Cr-containing supersaturated solid solution. The electrochemical behavior was characterized by using electrode impedance spectroscopy (EIS) and potentiodynamic polarization curves. Electrochemical results demonstrated that, compared to the initial specimen, all the irradiated specimens showed better corrosion resistance in 0.01 mol LiOH solution, among which 25-pulsed specimen possessed the best corrosion resistance. Surface selective purification, supersaturated Fe, Cr elements in substrate and abundant structure defects jointly promoted the improvement of the corrosion resistance.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 438〈/p〉 〈p〉Author(s): Gunther Korschinek, Thomas Faestermann〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The experiments searching in solar system bodies for freshly produced radionuclides from outside the solar system are reviewed, with a special focus on accelerator mass spectrometry. A surplus of 〈sup〉60〈/sup〉Fe has been found at eight locations in terrestrial oceans as well as in lunar samples. This surplus is attributed to supernova activity within 300 light years from the Sun about 1.5 to 3.0 Ma ago. An intensive search for the r-process nuclide 〈sup〉244〈/sup〉Pu in deep-ocean material yielded an upper limit far below the expectation if it were produced exclusively by core-collapse supernovae. Thus, a much less frequent stellar event than core-collapse supernovae must be the site where the heaviest nuclides are produced.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 436〈/p〉 〈p〉Author(s): Zhimei Yang, Fan Lan, Yun Li, Min Gong, Mingmin Huang, Bo Gao, Junkui Hu, Yao Ma〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The effects of the atomic migration between metal and semiconductor by swift heavy ion (SHI) irradiation on the turn on voltage (V〈sub〉on〈/sub〉), ideality factor (〈em〉n〈/em〉) and Schottky barrier height (SBH) in 4H-SiC Schottky barrier diodes (SBD) have been researched. The results show that the 〈em〉n〈/em〉 decreases and SBH increases for 4H-SiC SBDs without irradiation and with 5 × 10〈sup〉9〈/sup〉 ions/cm〈sup〉2〈/sup〉 at increasing testing temperature. After irradiation, the V〈sub〉on〈/sub〉 and SBH of the sample increases due to the forming of higher barrier height TiSi〈sub〉x〈/sub〉 by annealing treatment at 873 K. The SHI and annealing treatment can make the deep level defect to be partly recovered. The results may be explained that the interfacial structure was modified due to the silicon and carbon atomic migration during SHI process at the interfacial region between metal and semiconductor, and then reacting at high temperature annealing treatment.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 436〈/p〉 〈p〉Author(s): Xingguo Feng, Kaifeng Zhang, Yugang Zheng, Hui Zhou, Zhihua Wan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Cr-Zr-N films were deposited in a DC magnetron sputtering system with Cr and Zr targets under the mixed Ar and N〈sub〉2〈/sub〉 gases. The effect of the Zr content on structure, morphology, hardness and tribological behavior of Cr-Zr-N films were systematically investigated. The XRD result showed that all the Cr-Zr-N films exhibited FCC structure. FESEM indicated that the morphologies of the film changed from particular surface feature with a faceted polygon to granular-like structure as the Zr content increased. Nano-indentation results exhibited that with an increase of the Zr content in the films, the hardness and elastic modulus linearly increased and reached maximum values of 27.1 GPa and 350.5 GPa at a Zr content of 20.8 at.%. Tribological test results indicated that the wear rate decreases remarkably from 3.2 × 10〈sup〉−14〈/sup〉 m〈sup〉3〈/sup〉/Nm to 0.98 × 10〈sup〉−14〈/sup〉 m〈sup〉3〈/sup〉/Nm with increasing Zr content in the films from 1.0 at.% to 20.8 at.%.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 28 September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): Luis A. Marqués, María Aboy, Iván Santos, Pedro López, Fuccio Cristiano, Antonino La Magna, Karim Huet, Toshiyuki Tabata, Lourdes Pelaz〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We combine focused experiments with molecular dynamics simulations to investigate in detail the formation of {0 0 1} loops in nanosecond laser-annealed silicon. We demonstrate that at temperatures close to the melting point, self-interstitial rich silicon is driven into dense liquid-like droplets that are highly mobile within the solid crystalline matrix. These liquid droplets grow by a coalescence mechanism and eventually transform into {0 0 1} loops through a liquid-to-solid phase transition in the nanosecond timescale.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 18 September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): Wataru Kada, Ivan Sudić, Natko Skukan, Shunsuke Kawabata, Takahiro Satoh, Junichi Susaki, Suzuya Yamada, Takahiro Sekine, Raj Kumar Parajuli, Makoto Sakai, Kenta Miura, Masashi Koka, Naoto Yamada, Tomihiro Kamiya, Milko Jakšić, Osamu Hanaizumi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Two different types of SiAlON phosphors, namely, α-SiAlON:Eu and β-SiAlON:Eu, that have been developed as scintillators are evaluated for their luminescent properties by ion-beam-induced luminescence (IBIL) analysis under 2–3-MeV H〈sup〉+〈/sup〉-microbeam irradiation. The IBIL spectra show that both α-SiAlON:Eu and β-SiAlON:Eu have bright luminescence similar to that of ZnS:Ag scintillators. The α-SiAlON:Eu and β-SiAlON:Eu IBIL spectra have peaks at wavelengths of 605 and 540 nm, respectively, which lie in the preferred range of general optical sensors. As the irradiation progresses, the IBIL intensity of conventional ZnS:Ag scintillators decreases sharply, whereas that of the two SiAlONs remains largely unchanged. Moreover, the thermal resistivity of β-SiAlON:Eu is measured by IBIL under temperature control. The IBIL intensity retains half of its original value at the highest temperature of 773 K. The present experimental results reveal the two different types of SiAlON to be potential candidates for a scintillation monitoring tool for harsh environments in which intense beam irradiation at high temperature can be expected.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 3 September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): M. Roumie, I. Oggiano, A. Reslan, A. Srour, Z. El-Morr, M. Castiglione, M. Tabbal, M. Korek, B. Nsouli〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The study the ancient Phoenician cult place of Kharayeb, in the rural hinterland of Tyre, southern of Lebanon, dated to the Iron Age and Hellenistic periods is particularly helpful in evaluating the complexity and variability of the so called “Hellenism” and of “Greek cultural influences” in the Phoenician world. The PIXE analytical technique was used to characterize the elemental composition of several artefacts from this archaeological site, mainly figurines and some artisanal objects, with an attempt to analyze geological samples that could be potential clay sources in the area. Furthermore, the PIXE information about the composition of the studied objects helped to understand if the figurines were locally produced or imported from the coast and how was the process of production connected to the sanctuary. Hence, particle induced X-ray emission technique PIXE was used to determine the elemental composition of about 57 excavated fragments of figurines and pottery from Kharayeb site, as well as from two another archaeological sites, Jemjim and Tyre which is the prestigious city of antiquity, located on the eastern Mediterranean coast. Then, PIXE analyses with multivariate statistical methods were used to compare and to reveal characteristic groups. Finally, PIXE technique contributed to establish a first database of chemical composition of Phoenician pottery, which will broaden the existing database currently related only to archaeological pottery from coastal sites in Lebanon. Therefore, this work will probably be used for any future archaeological study on Phoenician pottery in the Phoenician colonies in the Mediterranean basin.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 434〈/p〉 〈p〉Author(s): Sergei Ghyngazov, Sergey Pavlov, Valeria Kostenko, Anatoly Surzhikov〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The modification effects of the subsurface layers of alumina ceramics under irradiation by high-power carbon beam are investigated. Irradiation was performed on TEMP ion beam accelerator at a residual pressure of 10〈sup〉−4〈/sup〉 Torr. The energy of accelerated ions was 200 keV. The current density per pulse varied within 15–85 A/cm〈sup〉2〈/sup〉. Mechanical properties and phase composition in subsurface ceramics layers before and after irradiation were analyzed by microhardness testing and X-ray diffraction, respectively. No changes in the ceramics phase composition were observed. It was found that the treatment of ceramics with a powerful pulsed ion beam leads to a significant change in the microhardness of subsurface layers. The increase in microhardness depends on the current density and the deposited energy. The greatest increase in microhardness (up to 2.5 times) is observed at a current density of 50 A/cm〈sup〉2〈/sup〉.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 434〈/p〉 〈p〉Author(s): Vanaraj Solanki, D. Kabiraj, D.K. Avasthi, Shikha Varma〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The topographic evaluation of the nano-scale pattern, on ZnO (001) surface, and its scaling properties have been investigated here after low energy atom beam irradiation. Preferential sputtering promotes the formation of Zn-rich zones near the surface that serve as the nucleation centers for the spontaneous nanostructure growth. The rms roughness (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈mi〉σ〈/mi〉〈/mrow〉〈/math〉) however increases with irradiation fluence and displays power law behaviour, 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si4.gif" overflow="scroll"〉〈mrow〉〈mi〉σ〈/mi〉〈mo〉∼〈/mo〉〈msup〉〈mrow〉〈mtext〉t〈/mtext〉〈/mrow〉〈mrow〉〈mi〉β〈/mi〉〈/mrow〉〈/msup〉〈/mrow〉〈/math〉, for 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si5.gif" overflow="scroll"〉〈mrow〉〈mtext〉t〈/mtext〉〈mo〉〈〈/mo〉〈msub〉〈mrow〉〈mtext〉t〈/mtext〉〈/mrow〉〈mrow〉〈mi〉c〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 (crossover time) but saturates at longer time scale. In the case of 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si6.gif" overflow="scroll"〉〈mrow〉〈mtext〉t〈/mtext〉〈mo〉〉〈/mo〉〈msub〉〈mrow〉〈mtext〉t〈/mtext〉〈/mrow〉〈mrow〉〈mi〉c〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉, 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈mi〉σ〈/mi〉〈/mrow〉〈/math〉 is independent of irradiation time but interestingly follows the power law behaviour 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si8.gif" overflow="scroll"〉〈mrow〉〈mi〉σ〈/mi〉〈mo〉∼〈/mo〉〈msup〉〈mrow〉〈mtext〉L〈/mtext〉〈/mrow〉〈mrow〉〈mi〉α〈/mi〉〈/mrow〉〈/msup〉〈/mrow〉〈/math〉, where L is the size of image used in analysis. The morphology of the surfaces has also been investigated using the height-height correlation and power spectral density methods. The observed values of growth (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si9.gif" overflow="scroll"〉〈mrow〉〈mi〉β〈/mi〉〈/mrow〉〈/math〉) and roughness (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si10.gif" overflow="scroll"〉〈mrow〉〈mi〉α〈/mi〉〈/mrow〉〈/math〉) exponents indicate a scaling behavior that is induced by the disordered but well-defined geometry of the nanostructures.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 436〈/p〉 〈p〉Author(s): Congyu Hao, Xiangyan Li, Yange Zhang, Yichun Xu, Yan Jiang, C.S. Liu, Q.F. Fang, Xianping Wang, Tao Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Neutrons induce displacement damage to the tungsten-based plasma facing material by creating radiation-defects, e.g., vacancies (Vs) and self-interstitial atoms (SIAs). These defects will accumulate on the surface and further affect surface's role as defect sinks. In this work, by combining molecular statics (MS) and object kinetic Monte Carlo (OKMC) methods, we study the clustering of the V/SIA on the two typical low-index W surfaces (1 0 0) and (1 1 0) to uncover the effect of the agglomerated surface V/SIA on the segregation and annihilation of the V and SIA nearby. Results show that the V〈sub〉n〈/sub〉/SIA〈sub〉n〈/sub〉 could form on the two surfaces via the agglomeration of the V/SIA on the surfaces with the energy release and the reduced energy barrier for the V/SIA diffusion near the V〈sub〉n〈/sub〉/SIA〈sub〉n〈/sub〉 as respective energetic and kinetic driving force. Yet, the V〈sub〉n〈/sub〉/SIA〈sub〉n〈/sub〉 is more easily formed on surface (1 1 0) compared to surface (1 0 0) due to the much larger binding energy of a V with a V〈sub〉n〈/sub〉 (or a SIA with a SIA〈sub〉n〈/sub〉) and lower diffusion energy barrier of the V/SIA on surface (1 1 0) than that on surface (1 0 0). Long-term OKMC simulations of the V/SIA behavior near the surfaces at 1000 K show that surface (1 0 0) could develop to locally convex structures due to the SIA agglomeration, while surface (1 1 0) will evolve to locally concave-convex structures due to the V/SIA clustering. Meanwhile, the interaction mechanism of the V/SIA with the surface is changed from the fundamental segregation, annihilation and clustering of the V/SIA near a pure surface to the trapping for the V/SIA by the locally concave-convex structure and the junction.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 436〈/p〉 〈p〉Author(s): Vladimir Epp, Julia Janz, Margarita Zotova〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We study theoretically the angular momentum of radiation emitted at axial channeling of the fast particles in a crystal or in a bunch of micro- or nanotubes placed in strong magnetic field. It is shown that high energy particles channeled in the presence of magnetic field are effective source of vortex radiation in the X-ray and gamma-range of photons energies. We show that there are two factors that increase the angular momentum of emitted radiation in the presence of magnetic field. First, the magnetic field favours additional “twisting” of the channeled particles in a certain direction and, secondly, the particles that have the corresponding initial angular momentum are predominantly captured into the channeling mode. Dependence of the angular momentum of radiation on the value of magnetic field and on the incident angle is studied.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 12 September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): J. Botsoa, T. Sauvage, B. Courtois, D. De Sousa Meneses, M.F. Barthe〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nuclear reaction analysis (NRA) has been used for the determination of nitrogen content in diamond by monitoring the 〈sup〉14〈/sup〉N(d,p〈sub〉0〈/sub〉)〈sup〉15〈/sup〉N nuclear reaction from a 1.4 MeV deuteron beam incident on the diamond samples. Results obtained in bulk diamond are compared to those inferred from infrared optical transmission measurements. Furthermore, nitrogen content has also been measured by NRA in diamond nanoparticles and in the light of these results we evaluate the conversion of nitrogen to nitrogen-vacancy (NV) complexes in both bulk diamond and diamond nanoparticles after a 2.4 MeV-proton irradiation and subsequent thermal annealing.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 436〈/p〉 〈p〉Author(s): Xin Yang, Xiangguo Zeng, Liang Chen, Yang Guo, Huayan Chen, Fang Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Atom-scale numerical calculations were performed to investigate the damage behavior in close-packed hexagonal zirconium (HCP-Zr) by primary irradiation through a molecular dynamics (MD) study. The influences of Primary Knock-on Atom (PKA) energy (〈em〉E〈/em〉〈sub〉PKA〈/sub〉), the PKA incident direction and the ambient temperature (〈em〉T〈/em〉) on the cascade collision were studied comprehensively. The results show that the athermal recombination corrected displacements per atom (arc-dpa) model is more accurate in comparison with the Norgett-Robinson-Torrens (NRT) model when predicting the steady vacancy (〈em〉N〈/em〉〈sub〉s〈/sub〉). It was found that the vacancy peak (〈em〉N〈/em〉〈sub〉peak〈/sub〉), the peak time (〈em〉t〈/em〉〈sub〉peak〈/sub〉), and the steady time (〈em〉t〈/em〉〈sub〉s〈/sub〉) increase as 〈em〉E〈/em〉〈sub〉PKA〈/sub〉 and 〈em〉T〈/em〉 increase. The steady vacancy also increases with the increase of 〈em〉E〈/em〉〈sub〉PKA〈/sub〉. It was also found that 〈em〉N〈/em〉〈sub〉s〈/sub〉 increases and subsequently decreases by increasing 〈em〉T〈/em〉, suggesting that there is a suitable temperature to maximize 〈em〉N〈/em〉〈sub〉s〈/sub〉 when 〈em〉E〈/em〉〈sub〉PKA〈/sub〉 is constant. In addition, it was discovered that the PKA incident direction has little effect on vacancy dynamic history. It was proved that 〈em〉E〈/em〉〈sub〉PKA〈/sub〉 can worsen the irradiation damage in crystal Zr, but 〈em〉T〈/em〉 can relieve such damage. In addition, the incident direction was found to have an insignificant effect on the damage. This study highlights that the steady vacancy concentration (〈em〉C〈/em〉) can characterize the material irradiation damage.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 436〈/p〉 〈p〉Author(s): Lihu Yang, Vladyslav Rayda, Xiaolei Zhao, Sarah Murseli, Xianfang Song, Ian D. Clark〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper describes a technique of making carbonate by rapid CO〈sub〉2〈/sub〉 capture from groundwater for direct measurement of the 〈sup〉14〈/sup〉C content by accelerator mass spectrometry (AMS). The DIC in groundwater was extracted from acidified water in the form of carbon dioxide (CO〈sub〉2〈/sub〉), and transferred into saturated barium hydroxide solution to form barium carbonate (BaCO〈sub〉3〈/sub〉). After the BaCO〈sub〉3〈/sub〉 precipitate was freeze-dried, it was mixed with a metal powder and pressed into an AMS target for measurement. The behaviors of Si, Al, Fe and Ta powder as the binder with carbonate were evaluated. The C〈sup〉3+〈/sup〉 currents from carbonate targets mixed with Fe or Ta were found generally larger than those with Si or Al by a factor of two. The baked Ta was shown to produce fewer contaminating 〈sup〉14〈/sup〉C counts than all the others, with or without baking. The CaCO〈sub〉3〈/sub〉/Ta and BaCO〈sub〉3〈/sub〉/Ta mass mixing ratios in the range from 1:2 to 1:4 and in 1:1.5, respectively, produced optimized currents. The precision and accuracy of the measurement by direct CaCO〈sub〉3〈/sub〉 or BaCO〈sub〉3〈/sub〉 sputtering using Ta as the binder, were evaluated in comparison to a selected reference material. The agreement was reasonably good between the direct carbonate measurement and the high precision measurement through combustion and graphitization. These findings support the further development of a rapid assessment method directly from field work to measurement.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 436〈/p〉 〈p〉Author(s): Qing Huang, Hui Tang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉One IG-110 graphite sample was irradiated with 2 MeV Xe〈sup〉20+〈/sup〉 ions to a fluence of 2.4 × 10〈sup〉15〈/sup〉 ions/cm〈sup〉2〈/sup〉. Then the irradiated sample and one un-irradiated sample were tested in molten Li〈sub〉2〈/sub〉BeF〈sub〉4〈/sub〉 salt at a pressure of 0.3 MPa for 20 h, in order to investigate irradiation’s effects on graphite-Li〈sub〉2〈/sub〉BeF〈sub〉4〈/sub〉 salt compatibility. For both samples, the intruded salt have round surfaces and spherical salt particles with sizes 〈2 μm were shown on samples’ surface, indicating that irradiation did not change the non-wettability of Li〈sub〉2〈/sub〉BeF〈sub〉4〈/sub〉 salt to graphite. Besides, testing in molten Li〈sub〉2〈/sub〉BeF〈sub〉4〈/sub〉 salt did not have obvious effects on graphite’s surface morphology and Raman peaks, indicating that chemical attack did not happen to irradiated graphite. Therefore, irradiated graphite has a great structural stability in molten Li〈sub〉2〈/sub〉BeF〈sub〉4〈/sub〉 salt.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 25 September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): Jin-Hua Zhao, Han-Xu Zhang, Li-Li Ye, Guang-Tong Guo, Jing Guan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Sodium doped Calcium Barium Niobate (Na:CBN) is of potential use in integrated optical devices with high-power laser operation because of its unique nonlinear optical properties and the high Curie temperature. In our work, we research the fabrication and properties of planar Na:CBN waveguide by multiple energy He ion implantation. The sample is implanted with (450 + 500 + 550) keV He ions at room temperature with fluence of (3 + 3 + 3) × 10〈sup〉16〈/sup〉 ions/cm〈sup〉2〈/sup〉. Prism-coupling and end-face coupling measurements are used to investigate the optical properties of ion-implanted Na:CBN crystal. SRIM and FD-BPM simulations have been used to study the damage formation and light propagation process on the Na:CBN waveguide. Micro-Raman imaging is a powerful nondestructive approach to examine lattice modification and local micro-structural change. We perform confocal micro-Raman measurement, which is used to provide the information about the crystal structure of Na:CBN crystal after multiple energy He ion implantation. This work could provide useful information for integrated optical device based on Na:CBN crystal.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 436〈/p〉 〈p〉Author(s): S.N. Menon, B.S. Dhabekar, Sonal Kadam, D.K. Koul〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Lithium magnesium phosphate (LiMgPO〈sub〉4〈/sub〉) based phosphors have been found to be quite promising for optically stimulated luminescence (OSL) dosimetry. These phosphors have unique characteristic of linearity over a range of nine orders of magnitude of dose. However, the thermally stimulated luminescence (TL) and OSL signals of these phosphors fade with time. This constraint has limited the applicability of this phosphor in dosimetric application. This paper attempts to understand the cause and nature of fading. This paper also reports the synthesise of a new LiMgPO〈sub〉4〈/sub〉 based phosphor with less fading.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 11 September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): Tomoaki. Nishimura, Takeshi Kasai, Tomonori Mishima, Kazuo Kuriyama, Tohru Nakamura〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We investigated the conditions of sample preparation for obtaining low contact resistance to Al/Ti electrode on n-GaN fabricated by Si implantation and analyzed its interface structure. In conditions of sample preparation showing the lowest resistance, we found that there is an AlN layer and not the generally believed TiN layer on the interface between the electrode and the GaN substrate. Silicon was implanted into GaN followed by annealing at 1200 °C to investigate the effects of surface carrier concentration on ohmic contact. Layers of Ti and Al were then deposited and annealed at 550–800 °C. In the sample annealed at 600 °C with a relatively high fluence of 5 × 10〈sup〉14〈/sup〉 atoms/cm〈sup〉2〈/sup〉, the sample displayed the lowest contact resistance of 1.2 × 10〈sup〉−7〈/sup〉 Ωcm〈sup〉2〈/sup〉. This indicates that the formation of a high concentration of impurities on the GaN surface, resulting from Si implantation effectively reduced the contact resistance of the Al/Ti electrode. Ti and Al were also deposited on un-implanted GaN substrates, and the resulting multilayer electrodes with different Al/Ti ratios were annealed at 550–900 °C to investigate the electrode structure and the detail structure of metal/semiconductor interface. The film compositions and the interfacial microstructures of the samples were analyzed by the Rutherford backscattering spectroscopy method, optical microscopy, high-resolution scanning electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDX), and electron energy loss spectroscopy (EELS). For samples with Al/Ti ratios of ∼4.2, the under part of electrode became rich in Al at annealing temperatures of 550–600 °C. On the basis of the STEM and EELS analysis, Ti was not present at immediately above the GaN substrate interface, whereas AlN (thickness = 1–2 nm) was present. The RBS-determined total amount of Ga was 5 × 10〈sup〉15〈/sup〉 atoms/cm〈sup〉2〈/sup〉, which corresponds to the amount of Ga in 1.1 nm of the GaN layer that is probably replaced by the AlN layer.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 436〈/p〉 〈p〉Author(s): F. Ditrói, S. Takács, H. Haba, Y. Komori, M. Aikawa, M. Saito, T. Murata〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Natural silver targets have been irradiated by using a 50 MeV alpha-particle beam in order to measure the activation cross sections of radioisotopes in the 40–50 MeV energy range. Among the radio-products there are medically important isotopes such as 〈sup〉110m〈/sup〉In and 〈sup〉111〈/sup〉In. For optimizing the production of these radioisotopes and regarding their purity and specific activity the cross section data for every produced radioisotope are important. New data are measured in this energy range and the results of some previous measurements have been confirmed. Physical yield curves have been calculated by using the new cross section data completed with the results from the literature.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 6 September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): Sou Watanabe, Yuya Katai, Haruaki Matsuura, Wataru Kada, Masashi Koka, Takahiro Satoh, Tsuyoshi Arai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉IBIL and EXAFS analyses were carried out on an adsorbent impregnating CMPO and HDEHP extractants for the extraction chromatography technology in order to evaluate chemical structure of complex formed in the adsorbent. EXAFS analysis suggested that contributions of CMPO and HDEHP for Eu(III) extraction must be not only individual ones but also cooperative. IBIL spectra obtained for the adsorbent were attributed to complexes of Eu(III) with organic compounds, and the profile was sensitive to coordination structure of the organic compounds. Those analytical technologies were shown to be effective to investigate chemical environment of cation charged in organic compounds. Two dimensional imaging using specific luminescence was also tried on the adsorbent, and required performance for the system to evaluate distribution of the complexes inside the particle was clarified.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 436〈/p〉 〈p〉Author(s): Q.M. Xu, Z.H. Yang, Y.P. Guo, Y.H. Chen, X.M. Zhou, H.P. Liu, H.Y. Zhao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper reports the measurement of visible light emission in the collisions of slow (〈em〉V〈/em〉 ∼ 0.38 〈em〉V〈/em〉〈sub〉Bohr〈/sub〉) highly charged Xe〈sup〉q+〈/sup〉 (6 ≤ q ≤ 23) ions with GaAs surface. The experimental results include Ga I lines from the 4d 〈sup〉2〈/sup〉D〈sub〉3/2〈/sub〉 and 5 s 〈sup〉2〈/sup〉S〈sub〉1/2〈/sub〉 to the 4p 〈sup〉2〈/sup〉P〈sub〉1/2,3/2〈/sub〉 states and Ga II lines belonged to the electron transitions 4p〈sup〉2〈/sup〉〈sup〉1〈/sup〉D〈sup〉2〈/sup〉 → 4s4p 〈sup〉1〈/sup〉P〈sub〉1〈/sub〉, 4s5s 〈sup〉1〈/sup〉S〈sub〉0〈/sub〉 → 4s4p 〈sup〉1〈/sup〉P〈sub〉1〈/sub〉 and 4s4f 〈sup〉1〈/sup〉F〈sub〉3〈/sub〉 → 4s4d 〈sup〉3〈/sup〉D〈sub〉3〈/sub〉. The measurement on the projectile charge state dependences of Ga II at 270.20, 277.90, 426.20 nm and Ga I at 287.65, 294.55, 403.55, 417.35 nm lines is presented. It is concluded that the photon yields increase with charge state in the same way as the potential energy increases and the potential energy is the driving force for optical emission of excited Ga atoms and Ga〈sup〉+〈/sup〉 ions.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 436〈/p〉 〈p〉Author(s): Meenakshi Singh, M.R. Singh, Anjali Sharma, Bhushan Dighe〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The discrimination of medieval silver coins into genuine and forged have been performed using WD-XRF and cross-sectional analysis by SEM-EDX. The study conclusively shows that forged coin was manufactured by plating silver over baser metal alloy of copper and lead that caused segregation and brittleness owing to their reduced solid solubility. Silver was alloyed with a small percentage of copper or sometimes with copper and lead in original coins leading to age-hardening embrittlement in the ternary silver-copper-lead system on cooling. The presence of zinc and tin in some analyzed coins indicate copper was added as an alloy. All the coins were gold amalgamated with the help of mercury on either surface observed through WD-XRF. The silver/copper ratio indicates more than one mint. Preferential mineralization of more chemically active phase occurred as isolated patina shows the presence of oxides of lead, copper, silver, magnesium, and silica through XRD analysis.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 434〈/p〉 〈p〉Author(s): 〈/p〉

Beschreibung: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 438〈/p〉 〈p〉Author(s): Y.Z. Jia, W. Liu, B. Xu, S.L. Qu, T.W. Morgan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The surface nano structures on W surface exposed to low-energy D plasma was studied by transmission electron microscopy. It was found that the surface nano structures on W surface induced by D plasma were mainly due to two reasons. First, the subsurface nano-sized bubbles will induce nano scale blistering of the surface, resulting in surface nano morphology. The nano scale blistering behaviour is most obvious on [1 1 1] surface at low temperature (500 K). Secondly, during the plasma exposure, oxide layer on W surface will be sputtered by low energy D particles, and the sputtering can also induce nano structures on some surfaces. At low temperature (500 K), the surface nano structures were formed due to the nano scale blistering behaviour and the sputtering of surface oxide layer. At high temperature (1000 K), the surface nano structures were mainly caused by the sputtering of surface oxide layer.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 30 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): Wanwisa Sudprasert, Ridthee Meesat, Harry J. Whitlow, Henry Udeogu, Armin B. De Vera, Naresh Deoli〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Mercury amalgams are still widely used in dentistry in many countries. There is considerable concern about uptake of Hg in both the patient and environment. It is an interesting question if the pathway is by Hg diffusion through the tissue of the tooth or dissolution in saliva or direct evaporation through inhaled air into the lung. Our previous study Meesat et al. (2017) of a high-Cu amalgam showed no evidence of diffusion through the enamel. However, a compositional change was observed on the biting surface of the amalgam which is indicative of tribochemical changes.〈/p〉 〈p〉To investigate the above observation in more detail, 17 adult teeth with amalgam fillings were obtained as operation-waste from dental clinics. The samples were embedded and sliced into 1 mm sections in the coronal plane of the tooth using a low/speed diamond saw with water-based cooling. Elemental maps from teeth treated with dental amalgam were measured using micro-PIXE.〈/p〉 〈p〉In common with our previous study Meesat et al. (2017), sharp interfaces between the enamel and amalgam were observed with no strong evidence for Hg diffusion in the enamel. Little evidence exists consistent with the presence of tribochemical alteration by mastication. However, Zn was observed to be localized at different sites in the amalgam/enamel interface.〈/p〉 〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 29 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): A. Ringvall Moberg, S. Warren, C. Muñoz Pequeño, J. Cruikshank, T. Giles, D. Hanstorp〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Molecular beams injected into the ISOLDE Radio-Frequency Quadrupole cooler and buncher (RFQcb), ISCOOL, have been studied under varying conditions using a new Time-of-Flight (ToF) detector. When a beam of molecules is injected into the RFQcb and interacts with the buffer gas, collisional dissociation processes may occur. In this study, two different beams of molecules, CO〈sup〉+〈/sup〉 and 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈msubsup〉〈mrow〉〈mi mathvariant="normal"〉N〈/mi〉〈/mrow〉〈mrow〉〈mn〉2〈/mn〉〈/mrow〉〈mrow〉〈mo〉+〈/mo〉〈/mrow〉〈/msubsup〉〈/mrow〉〈/math〉, were separately injected into ISCOOL, and two different buffer gases (pure helium or a 90:10 mixture of helium and neon) were used. The radio-frequency of the RFQcb was varied as the molecules, along with the fragments from the dissociation processes, were extracted from ISCOOL and studied using the new Time-of-Flight detector. The main finding of this work is that the rates for molecular dissociation within ISCOOL were very small for both CO〈sup〉+〈/sup〉 and 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈msubsup〉〈mrow〉〈mi mathvariant="normal"〉N〈/mi〉〈/mrow〉〈mrow〉〈mn〉2〈/mn〉〈/mrow〉〈mrow〉〈mo〉+〈/mo〉〈/mrow〉〈/msubsup〉〈/mrow〉〈/math〉, with the largest rates found for CO〈sup〉+〈/sup〉.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 447〈/p〉 〈p〉Author(s): S. Petrović, N. Starčević, M. Ćosić〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This work is devoted to the construction of the universal axial (0 0 1) rainbow channeling proton-crystal interaction potential. It has been done by modifying the Moliere’s interaction potential. We show that for very thin crystals with the cubic crystallographic structure, in the (0 0 1) orientation with respect to 2 MeV proton beams, it is possible to obtain a universal proton-crystal interaction potential from the morphological analysis of the rainbows in the proton transmission angular plane.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 28 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): R.C. Pereira, A.L.F. de Barros, D. Fulvio, P. Boduch, H. Rothard, E.F. da Silveira〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉N〈sub〉2〈/sub〉O and CO〈sub〉2〈/sub〉 can be formed in the interstellar space and in ices on the surface of outer solar system bodies, such as Pluto and Triton. Energetic ions can simulate the energy transfer processes that occur by cosmic ray irradiation of interstellar ices, comets, and icy solar system bodies. Proceeding systematic research, pure nitrous oxide (N〈sub〉2〈/sub〉O) ice, and nitrous oxide and carbon dioxide (CO〈sub〉2〈/sub〉) ice mixture were irradiated at 11 K with MeV-nitrogen (N〈sup〉+〈/sup〉) and -xenon (Xe〈sup〉23+〈/sup〉) ion beams. The chemical and physical effects induced by ion irradiation on the N〈sub〉2〈/sub〉O ice and the N〈sub〉2〈/sub〉O:CO〈sub〉2〈/sub〉 ice mixture are compared. The formation and dissociation cross sections scale with the electronic stopping power (S〈sub〉e〈/sub〉) roughly as σ ∼ a S〈sub〉e〈/sub〉〈sup〉n〈/sup〉, where n ∼ 3/2. The n power law is helpful for predicting the N〈sub〉2〈/sub〉O formation and dissociation cross-sections for other ion beam projectiles and energies; these predictions will allow estimating the effects of the entire cosmic ray radiation field.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 447〈/p〉 〈p〉Author(s): S. Gouasmia, M. Benguerba〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A theoretical approach is developed to describe the dominant features of process by which craters form on the copper, gold and solid argon surfaces under self impacts of high velocity cluster ions. It is showed that, in the shock wave conditions generated at the impact of cluster on the surface, the dynamical process begins when the shock reaches the target free surface inducing the formation of a rarefaction wave(release wave) which propagates inward into the compressed region. The rarefaction causes the shocked material to move toward the free surface and expand into a vacuum forming the crater. It is found that the size of cluster has a significant influence on the mechanism of crater formation. In addition to metals (Cu and Au) the proposed approach has been successfully extended to impact of argon clusters on solid argon substrate. The approach has been validated using molecular dynamics simulated data for copper, gold and argon available in the literature. All simulated crater volumes have been analytically reproduced with a good agreement on the basis of a hemispherical shape.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 28 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): Benedict Seiferle, Lars von der Wense, Ines Amersdorffer, Nicolas Arlt, Benjamin Kotulski, Peter G. Thirolf〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉〈sup〉229〈/sup〉Th is the only known nucleus with an excited state that offers the possibility for a direct laser excitation using existing laser technology. Its excitation energy has been measured indirectly to be 7.8(5) eV (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si7.gif" overflow="scroll"〉〈mrow〉〈mo〉≈〈/mo〉〈/mrow〉〈/math〉160 nm). The energy and lifetime of the isomeric state make it the presently only suitable candidate for a nuclear optical clock, the uncertainty of the excitation energy is, however, still too large to allow for a direct laser excitation in a Paul trap. Therefore, a major goal during the past years has been an improved energy determination. One possible approach is to measure the kinetic energy of electrons which are emitted in the internal conversion decay of the first isomeric state in 〈sup〉229〈/sup〉Th. For this reason an electron spectrometer based on a magnetic bottle combined with electrical retarding fields has been built. Its design, as well as first test measurements are presented, which reveal a relative energy resolution of 3 % and thus enable to measure the electrons’ expected kinetic energy to better than 0.1 eV. This is sufficiently precise to specify a laser system able to drive the nuclear clock transition in 〈sup〉229〈/sup〉Th.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 447〈/p〉 〈p〉Author(s): M. Käyhkö, M. Laitinen, K. Arstila, I.J. Maasilta, T. Sajavaara〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A new beamline for high energy resolution PIXE measurements is presented. This new setup includes options for both in-air and vacuum measurements. For the high energy resolution transition-edge sensor array, a polycapillary lens is used for detecting low-energy X-rays down to 0.5 keV and to increase the effective solid angle. X-ray transmission of the polycapillary lens was characterized using two calibration standards. The gain obtained by adding a polycapillary lens was 1.6–2.3 at energies between 2.1 keV and 4.5 keV. From 1.04 to 1.74 keV the gain is increased to 2.1–3.0, and at energies 4.9–8.0 keV the gain is between 1.6 and 0.65. The measured gain agreed well with theoretical calculations. The lightest detectable element in the new setup is oxygen at 0.525 keV.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 447〈/p〉 〈p〉Author(s): Jay D. Dias, Naresh T. Deoli, Deborah Rogers, Armin de Vera, Karen M. Smith, Robin Schneider-Broussard, Harry J. Whitlow〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The development of a facility for irradiation of murine and primate tissue presents several challenges. First, extremely low fluences (10〈sup〉6〈/sup〉–10〈sup〉11〈/sup〉 ions cm〈sup〉−2〈/sup〉) are required to deliver doses of 1 mGy–50 Gy using MeV proton. Second, the tissues, particularly from non-human primate, may be infectious to humans. Third, protection of irradiated tissue samples from contamination by mold and bacteria is critical. Here we present an ultra-low flux irradiation facility and associated fluence control for biological cell and tissue irradiation under sterile biosafety level-2 conditions suitable for use with low energy (1–3.4 MeV) protons. The operation is demonstrated using murine astrocytes.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 28 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): A.M. Borisov, N.G. Chechenin, V.A. Kazakov, E.S. Mashkova, M.A. Ovchinnikov〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The regularities of surface corrugation of polyacrylonitrile based carbon fibers reinforcing composite KUP-VM has been studied experimentally after high-fluence 30 keV Ne〈sup〉+〈/sup〉, 20 and 30 keV Ar〈sup〉+〈/sup〉, 30 keV N〈sub〉2〈/sub〉〈sup〉+〈/sup〉 ion irradiation at target temperatures ranging from 100 to 600 °C. It was found that periodic corrugated structure parameters, such as the angles of the inclination β of the corrugations and their fraction on the fiber surface have strong temperature dependences. The periodicity of corrugations for all used ions slightly decreases with increasing temperature and is of the order of hundreds of nanometers. For neon and argon ions the corrugation inclination angles and the fraction in contrary of nitrogen ions show minima at the temperatures near 400 °C which corresponds to the minimum of radiation-induced dimensional changes in carbon materials. The depth of the minima at 400 °C depends on the competition of the processes of ion-induced plastic deformation of carbon materials and ion bombardment sputtering. For nitrogen ions the inclination angles increase with temperature so that at temperature ∼270 °C they reach maximum values ∼40°, staying at this level at subsequent temperature elevation up to 600 °C. The qualitative difference in the temperature dependences of fiber corrugation for noble gas ions and nitrogen ones is connected to nitrogen chemical activity and the creation of C〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉N bonds under nitrogen ion implantation.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 447〈/p〉 〈p〉Author(s): S.A. Shojaee, Y. Qi, Y.Q. Wang, T. Prenzel, A. Mehner, D.A. Lucca〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The microstructural relaxation caused by heat treatment of ion-irradiated silica-based thin films was investigated. Hybrid organic-inorganic silica-based thin films were synthesized via a sol-gel process and were irradiated with 125 keV H〈sup〉+〈/sup〉 or 250 keV N〈sup〉2+〈/sup〉 ions with fluences of 10〈sup〉15〈/sup〉 or 10〈sup〉16〈/sup〉 ions/cm〈sup〉2〈/sup〉. Ion irradiation was followed by heat treatment at 1100 °C or 1350 °C in an inert Ar atmosphere. The microstructure of the irradiated films before and after heat treatment was studied with a combination of Raman and infrared spectroscopies. The results indicated that while ion irradiation led to a defective structure of silica and graphitic C nanodomains, subsequent heat treatment led to structural relaxation and atomic reconfiguration of both silica and C. After heat treatment at 1100 °C, the microstructure of the films consisted of nanocrystalline graphite and structurally relaxed silica. After secondary heat treatment at 1350 °C, most of the C within the films vanished and the film microstructure only consisted of α-cristobalite silica.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 26 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): M. Cutroneo, L. Torrisi, V. Havranek, A. Mackova, P. Malinsky, A. Torrisi, J. Stammers, Z. Sofer, L. Silipigni, B. Fazio, M. Fazio, R. Böttger〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Graphene oxide (GO) is an electrical insulator as most of the carbon atoms in this material are sp〈sup〉3〈/sup〉-hybridized. Its physical, optical and chemical properties depend on the type and degree of reduction process. Presently, copper ion irradiation of GO foil has been performed at Ion Beam Center of the Helmholtz-Zentrum Dresden-Rossendorf to investigate the behavior of a set of GO foils under this irradiation at low energy and different fluences up to 5 × 10〈sup〉16〈/sup〉 ions/cm〈sup〉2〈/sup〉. The compositional and optical properties of graphene oxide have been studied as a function of the fluences of implanted copper ions in the wavelength range 400–1000 nm. The results of ellipsometry microscopy, helium Rutherford backscattering spectroscopy, elastic recoil detection analysis, Raman spectroscopy and SEM-EDX measurements will be presented and discussed.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 25 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): Lucio Calcagnile, Lucio Maruccio, Luigi Scrimieri, Domenico delle Side, Eugenia Braione, Marisa D'Elia, Gianluca Quarta〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Centre for Dating and Diagnostics was established in 2001 at the University of Salento with the aim of becoming a National Centre for radiocarbon dating by AMS. After more than fifteen years of operation this goal has been fully achieved with thousands of dated samples for researches spanning from Archaeological, Earth and Forensics sciences to industrial and environmental applications. Furthermore, in the frame of different large scale National projects, the experimental potential of the facility has been substantially improved through the installation of new beam lines and experimental set-ups.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 29 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): Roman Voskoboinikov〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Molecular dynamics simulations were applied to study primary damage formation in collision cascades initiated by primary knock-on atoms (PKA) with energy 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si25.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mi〉E〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="italic"〉PKA〈/mi〉〈/mrow〉〈/msub〉〈mo〉=〈/mo〉〈mn〉5〈/mn〉〈/mrow〉〈/math〉, 10, 15 and 20 keV in aluminum at temperature 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si26.gif" overflow="scroll"〉〈mrow〉〈mi〉T〈/mi〉〈mo〉=〈/mo〉〈mn〉100〈/mn〉〈/mrow〉〈/math〉, 300 and 600 K. A series of 24 collision cascades for each 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si4.gif" overflow="scroll"〉〈mrow〉〈mrow〉〈mfenced open="(" close=")"〉〈mrow〉〈msub〉〈mrow〉〈mi〉E〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="italic"〉PKA〈/mi〉〈/mrow〉〈/msub〉〈mo〉,〈/mo〉〈mi〉T〈/mi〉〈/mrow〉〈/mfenced〉〈/mrow〉〈/mrow〉〈/math〉 set was simulated in order to assure statistical reliability of the obtained results. The number of Frenkel pairs, fraction of vacancies 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si28.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mi〉σ〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="italic"〉vac〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 and self-interstitials (SIA) 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si29.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mi〉σ〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="italic"〉SIA〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 in point defect clusters, the average vacancy 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si30.gif" overflow="scroll"〉〈mrow〉〈mrow〉〈mfenced open="〈" close="〉"〉〈mrow〉〈msub〉〈mrow〉〈mi〉N〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="italic"〉vac〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/mfenced〉〈/mrow〉〈/mrow〉〈/math〉 and SIA 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si31.gif" overflow="scroll"〉〈mrow〉〈mrow〉〈mfenced open="〈" close="〉"〉〈mrow〉〈msub〉〈mrow〉〈mi〉N〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="italic"〉SIA〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/mfenced〉〈/mrow〉〈/mrow〉〈/math〉 cluster size, the average vacancy 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si32.gif" overflow="scroll"〉〈mrow〉〈mrow〉〈mfenced open="〈" close="〉"〉〈mrow〉〈msub〉〈mrow〉〈mi〉Y〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="italic"〉vac〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/mfenced〉〈/mrow〉〈/mrow〉〈/math〉 and SIA 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si33.gif" overflow="scroll"〉〈mrow〉〈mrow〉〈mfenced open="〈" close="〉"〉〈mrow〉〈msub〉〈mrow〉〈mi〉Y〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="italic"〉SIA〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/mfenced〉〈/mrow〉〈/mrow〉〈/math〉 cluster per cascade yield and the average cascade relaxation time 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si14.gif" overflow="scroll"〉〈mrow〉〈mrow〉〈mfenced open="〈" close="〉"〉〈mrow〉〈msub〉〈mrow〉〈mi〉τ〈/mi〉〈/mrow〉〈mrow〉〈mi〉c〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/mfenced〉〈/mrow〉〈/mrow〉〈/math〉 were evaluated as a function of 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si4.gif" overflow="scroll"〉〈mrow〉〈mrow〉〈mfenced open="(" close=")"〉〈mrow〉〈msub〉〈mrow〉〈mi〉E〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="italic"〉PKA〈/mi〉〈/mrow〉〈/msub〉〈mo〉,〈/mo〉〈mi〉T〈/mi〉〈/mrow〉〈/mfenced〉〈/mrow〉〈/mrow〉〈/math〉. It was established that collision cascades in aluminium split into subcascades along the projectile trajectory. As a result, 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si36.gif" overflow="scroll"〉〈mrow〉〈mrow〉〈mfenced open="〈" close="〉"〉〈mrow〉〈msub〉〈mrow〉〈mi〉σ〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="italic"〉vac〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/mfenced〉〈/mrow〉〈mo〉,〈/mo〉〈mrow〉〈mfenced open="〈" close="〉"〉〈mrow〉〈msub〉〈mrow〉〈mi〉σ〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="italic"〉SIA〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/mfenced〉〈/mrow〉〈mo〉,〈/mo〉〈mrow〉〈mfenced open="〈" close="〉"〉〈mrow〉〈msub〉〈mrow〉〈mi〉N〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="italic"〉vac〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/mfenced〉〈/mrow〉〈mo〉,〈/mo〉〈mrow〉〈mfenced open="〈" close="〉"〉〈mrow〉〈msub〉〈mrow〉〈mi〉N〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="italic"〉SIA〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/mfenced〉〈/mrow〉〈/mrow〉〈/math〉 and 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si14.gif" overflow="scroll"〉〈mrow〉〈mrow〉〈mfenced open="〈" close="〉"〉〈mrow〉〈msub〉〈mrow〉〈mi〉τ〈/mi〉〈/mrow〉〈mrow〉〈mi〉c〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/mfenced〉〈/mrow〉〈/mrow〉〈/math〉 do not depend on 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si23.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mi〉E〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="italic"〉PKA〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 26 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): Danuta Michalska〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The methods of production of anthropogenic carbonaceous mortars makes them a valuable material for radiocarbon dating. The probability of successful application of 〈sup〉14〈/sup〉C dating to mortars is related to the sample composition, not just the binder and added admixtures, but also the type, amount, and preservation state of the aggregate. The influence of different mortar components and applied pretreatments on dating results were demonstrated by 〈sup〉14〈/sup〉C measurements on samples for which the preparation technique was either chosen on the basis of their composition or applied in an arbitrary and pre-defined manner.〈/p〉 〈p〉Mortars from 7 different locations are presented here (37 samples analysed and compared). The preparation procedures utilize mechanical and chemical selection of material for 〈sup〉14〈/sup〉C measurements; collection of CO〈sub〉2〈/sub〉 at different times, during decomposition in orthophosphoric acid, is applied to carbonates obtained, for example, from grain size selection or from different portions of forced suspensions. An important point is that aside from detailed analysis and applied preparation, the sampling of a mortar from a well-defined position, not suspected of any reworking, is crucial. In presenting 〈sup〉14〈/sup〉C measurement results from different types of mortars and pretreatments, this paper illustrates the development of preparation methods over the years and the impact of their application on samples with different compositions.〈/p〉 〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 447〈/p〉 〈p〉Author(s): Gnansagar B. Patel, N.L. Singh, Fouran Singh, P.K. Kulriya〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the present investigation, the effects of ion beam irradiations on physicochemical and dielectric properties of the self-sustained chitosan/poly (ethylene oxide) blend film was studied. The blend film was formed via solution casting route due to its cost-effectiveness and ease of processing. These polymeric blend films were irradiated with C〈sup〉+5〈/sup〉 (60 MeV) and Ni〈sup〉+7〈/sup〉 (100 MeV) ions at different fluences. The tailored responses of polymeric material depend on electronic energy loss (〈em〉S〈sub〉e〈/sub〉〈/em〉) of the ions. The electronic energy loss within the matrix depends on mass, energy and atomic number of the impinging ion. XRD and FTIR analyses revealed alterations of crystalline size and diminished diverse modes of molecular vibration, respectively. Optical parameters were analyzed by employing Tauc and Fink approaches and unveiling the waning in band gap, carbonization of the polymeric matrix, respectively. The physicochemical modifications were well correlated with frequency dependent dielectric properties in the broad interval ranging from 20 Hz to 2 MHz. It reveals a significant enhancement in the dielectric outcomes owing to structural rearrangements upon a radiation treatment. Moreover, the XRD and FTIR studies were well complemented by DSC analysis. Observation of the hillocks-like structures and alteration of surface roughness upon exposure to radiation were examined by employing AFM.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 447〈/p〉 〈p〉Author(s): Boyi Zhang, Rodrigo Sato, Keiji Oyoshi, Hiroaki Mamiya, Masato Ohnuma, Yoshihiko Takeda〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We report on the spectral dependence of nonlinear optical response of Au nanocomposites in a broad photon energy (1.5–3.0 eV). Negative Au ions of 60 keV were implanted into amorphous SiO〈sub〉2〈/sub〉 substrates with a total fluence varying from 3 to 9 × 10〈sup〉16〈/sup〉 ion/cm〈sup〉2〈/sup〉 to fabricate nanoparticles. The average size of Au nanoparticles under different total fluence were estimated by small angle X-ray scattering, from which a threshold of size growth was determined at 6 × 10〈sup〉16〈/sup〉 ion/cm〈sup〉2〈/sup〉. Through the combined analysis of spectroscopic ellipsometry and pump and probe spectroscopy, we have evaluated the effective and intrinsic third order susceptibility for the composites and individual Au nanoparticles, respectively. Exhibiting from the measured transient transmission spectra, the effective third order susceptibility simultaneously show saturable absorption and reversed saturable absorption at different photon energy. In order to understand this spectral dependence, we clarified the intraband and interband contributions to the intrinsic third order susceptibility. A different balance between these two contributions was observed in tiny nanoparticles with radius of 1.5 nm.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 447〈/p〉 〈p〉Author(s): G. Hobler, D. Maciążek, Z. Postawa〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Atom redistribution is an important mechanism of ion bombardment induced spontaneous pattern formation in amorphous or amorphized targets. It may be characterized by either molecular dynamics (MD) simulations or by Monte Carlo (MC) simulations based on the binary collision approximation (BCA). In this work we analyze problems of the BCA approach in predicting atom redistribution by comparing MC and MD simulations of recoil events in amorphized Si. We find that the MC results critically depend on the displacement energy used, on the choice of the free flight paths and maximum impact parameters, and on the construction of the trajectories. Moreover, the net atom redistribution as determined by MD is significantly larger for recoils starting near the surface than for bulk recoils. The effect is not reproduced by the MC simulations.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 447〈/p〉 〈p〉Author(s): Tung Yuan Hsiao, ChienHsu Chen, Jaw-Wern Chiou, Huan Niu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, we prepared a p-type Ge thin film and then implanted Mn ions in it at room temperature. P-type Ge thin film was made by gallium ion implantation in to an n-type Ge substrate to provide additional hole carriers. Mn ions were implanted into the same layer with Ga ions. Helium ion beam induced epitaxial crystallization with 2 MeV was used to growth GeMn thin films. The results show the beam annealed GeMn sample has been regrowth and has magnetoresistance.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 10 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): Harry J. Whitlow, Patrick Jeanneret, Edouard Guibert, Liping Wang, Mathijs Van Der Meer〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Time-of-flight-energy elastic recoil detection analysis (ToF-E ERDA) is a uniquely powerful thin-film analytical technique because it can be used to measure simultaneously the depth distributions of all elements in a thin-film sample. The basic design of the time detectors which are generally based on the electron mirror has not changed significantly over 25 years or so. A classic electron optical study has been made to elucidate the factors that limit the time resolution of electron mirror time pick off detectors and how they are interrelated. Degradation of the time resolution is mainly associated with the electron divergence from an ideal straight trajectory and variations in the propagation of electromagnetic pulses over the anode surface. A set of equations that can be used to optimise time detector design are presented along with a new configuration that has an expected time resolution of 40 ps fwhm and overcomes most of the drawbacks of the conventional configuration.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 440〈/p〉 〈p〉Author(s): Ruibin Li, Chaohui He, Wei Chen, Junlin Li, Chenhui Wang, Guizhen Wang, Chao Qi, Shanchao Yang, Xiaoming Jin, Yan Liu, Xiaoyan Bai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Latch up (LU), an inherent destructive phenomenon owning to P-N-P-N structure in bulk Complementary Metal-Oxide -Silicon (CMOS) circuits, is highly sensitive to pulsed irradiation. A criterion for LU is concluded, and the impact of total ionizing dose (TID) on LU criterion is discussed. In the progress of accumulating TID, generated oxide trapped charges and interface states enhance surface recombination in the base of the parasitic bipolar junction transistor (PBJT), leading to increase of the base recombination current; and the trapped charges in the shallow trench isolation (STI) can also increase leakage current. In spite of hindering effect of the base recombination in PBJTs to LU, the STI leakage current plays a dominant role to gain sensitivity of LU. Experimental results confirm the fact that TID can lower the dose rate threshold for LU. For instance, the threshold in the device with doses 150 krad(Si) is nearly 50% lower than that in the pristine device. Simulations in SPICE and Sentaurus are conducted, and the results agree with that of experiments.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 7 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): S.M. Tunhuma, M. Diale, J.M. Nel, M.J. Madito, T.T. Hlatshwayo, F.D. Auret〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We have used confocal Raman spectroscopy, atomic force microscopy (AFM), Binary collision approximations and Deep level transient spectroscopy (DLTS) to study the defects introduced in n-type 4〈em〉H-〈/em〉SiC by 167 MeV Xe〈sup〉26+〈/sup〉 ions (swift heavy ions (SHIs)). Moderately doped epitaxial layers were irradiated with SHIs to a fluence of 5 × 10〈sup〉11〈/sup〉 cm〈sup〉−2〈/sup〉 at room temperature. Raman spectroscopy was used to investigate the effects of irradiation on the crystal structure. Raman intensity reduced after irradiation but the overall bond structure was conserved. Cluster spectra from confocal Raman spectroscopy showed a damage impact that was consistent with SRIM simulations. AFM showed that the incident radiation resulted in elongated protrusions. The virgin samples contained the E〈sub〉0.09〈/sub〉, E〈sub〉0.12〈/sub〉, E〈sub〉0.15〈/sub〉 and E〈sub〉0.65〈/sub〉 as the only electrically active defects. After irradiation the E〈sub〉0.40〈/sub〉 and E〈sub〉0.71〈/sub〉 defects were introduced.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 440〈/p〉 〈p〉Author(s): R.D. Perez, G.E. Falchini, F. Cometto Vincente, L. Soares, M.E. Poletti, H.J. Sánchez〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Conventional x-ray fluorescence analysis (XRF) is a powerful instrumental technique for elemental quantification of samples with a wide range of matrices coming from industry, medicine, biology, environmental and archaeometry. The scattering of the x-ray tube excitation beam from the matrix is mainly responsible of the strong background in XRF spectra which restricts the detection limit (DL) to a few ppm (w/w). One possible strategy to reduce the DL is the monochromatization of the excitation beam with a crystal monochromator. In this case, the optimization of the system components is strongly required to obtain the highest excitation count rate over the sample, since it is considerable reduced by the short energy band pass of the monochromator.〈/p〉 〈p〉In the present work an optical device composed by a Si(100) crystal monochromator and two parallel plates beam guides (PPBG) was characterized and including in a conventional XRF spectrometer to improve the DLs. The PPBGs are composed by several thin glass plate reflectors placed together and separated by spacers. Inside the gap, x-rays are transmitted by total reflection contributing to the photon flux at the output of the optical device. The first PPBG reduces the divergence of the beam striking the crystal, and the second one collects the monochromatic beam that emerges from the crystal. In this way, the design of the optical device is quite compact keeping a high photon flux at the output thanks to the wide acceptance solid angle of the PPBGs. The new XRF spectrometer was applied to the analysis of biological tissues. The first results obtained in this field are shown in the present work where the performance of the spectrometer can be evaluated.〈/p〉 〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 4 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): M.M. Saifulin, J.H. O'Connell, A. Janse van Vuuren, V.A. Skuratov, N.S. Kirilkin, M.V. Zdorovets〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Bulk yttrium-iron garnet (YIG) single crystals have been irradiated with swift Kr and Xe ions having energies from 0.4 to 22.8 MeV/u and electronic stopping powers from 8.9 to 28.9 keV/nm near the irradiated surface. Transmission electron microscopy (TEM) has been used for direct observation of non-overlapping amorphous latent tracks in the near surface region of the irradiated bulk YIG crystals. The amorphous track radii observed in this work have been compared with previously reported data from direct and indirect measurements. It was found that the thickness of the sample subjected to swift heavy ion irradiation does not significantly affect the resulting amorphous track size observed by TEM in YIG. The results also support previously observed consistency between direct TEM and indirect Rutherford backscattering in channelling mode (RBS/C) and Mossbauer spectroscopy (MS) methods for amorphous track evaluation in YIG when electronic stopping power is greater than ∼13 keV/nm, which is sufficient to create cylindrical amorphous tracks by high velocity ions (〈em〉E〈/em〉 〉 10 MeV/u). Indirect methods provide underestimated values compared to TEM when the electronic stopping power is below ∼13 keV/nm, for which discrete amorphous tracks are supposed to be formed by high velocity ions.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 440〈/p〉 〈p〉Author(s): Christian Bäumer, Claus Maximilian Bäcker, Marcel Gerhardt, Erik Grusell, Benjamin Koska, Kevin Kröninger, Christian Nitsch, Hannah Rullkötter, Hilda Milani Siregar, Beate Timmermann, Nico Verbeek, Jörg Wulff, Azad Yazgan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉This experimental study aims to measure nuclear cross sections from 〈sup〉nat〈/sup〉C and 〈sup〉27〈/sup〉Al which serve as reference targets regarding radioactivation in proton therapy. Graphite and aluminum foils were activated in broad, quasi-monochromatic proton fields generated with the pencil-beam scanning technique. The 〈em〉γ〈/em〉-emissions were analyzed subsequently in a nearby 〈em〉γ〈/em〉-ray spectrometry facility designed for low-level radioactivity measurements. The number of incident protons was measured with a Faraday Cup. A detailed evaluation of the uncertainties was performed.〈/p〉 〈p〉The cross section for the 〈sup〉nat〈/sup〉C(p,x)〈sup〉11〈/sup〉C reaction at 100 MeV is (70.2 ± 1.6 (sys.) ± 0.2 (stat.)) mb. The production cross sections from 〈sup〉27〈/sup〉Al at 100 MeV are (19.9 ± 0.4 ± 0.3) mb for 〈sup〉22〈/sup〉Na and (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si35.gif" overflow="scroll"〉〈mrow〉〈mn〉11.5〈/mn〉〈mo〉±〈/mo〉〈mn〉0.3〈/mn〉〈/mrow〉〈/math〉〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si36.gif" overflow="scroll"〉〈mrow〉〈mo〉±〈/mo〉〈mn〉0.1〈/mn〉〈/mrow〉〈/math〉) mb for 〈sup〉24〈/sup〉Na. The systematic uncertainties contribute 2.0%–2.4% of the quoted uncertainties (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si26.gif" overflow="scroll"〉〈mrow〉〈mi〉k〈/mi〉〈mo〉=〈/mo〉〈mn〉1〈/mn〉〈/mrow〉〈/math〉) of cross sections. Concluding, radioactivation cross sections were measured with proton fields in a clinically commissioned environment. The measured activation cross sections from aluminum used for monitoring of the proton fluence agree with the averaged values compiled in nuclear reaction data bases. For proton-induced radioactivation from carbon the chemical purity of the target strongly affects the experimental results. The cross section for the production of 〈sup〉11〈/sup〉C derived from a measurement with a high-purity graphite target is in line with the largest cross section obtained in prior studies.〈/p〉 〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 439〈/p〉 〈p〉Author(s): Toru Moriya, Mirei Takeyama, Hirohisa Sakurai, Toyoharu Umebayashi, Teiko Toyoguchi, Tadashi Shiraishi, Hiroko Miyahara, Motonari Ohyama, Kohei Nozawa, Satoshi Ito, Shigeru Itoh, Masashi Hirota, Fuyuki Tokanai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An accelerator mass spectrometry (AMS) system and an automated graphitization line were installed at Yamagata University (YU) in 2009. Approximately 2000 samples are measured per year using the YU-AMS system. The long-term stability of the system was assessed by measuring the standard sample IAEA-C7 graphitized by the automated graphitization line. In March 2014, a second automated graphitization line and an additional ion source for the YU-AMS system were installed to meet the requirement of 〈sup〉14〈/sup〉C measurement for pharmacological and medical applications. A phosphoric acid treatment system was also developed for the radiocarbon dating of calcium carbonate (CaCO〈sub〉3〈/sub〉) in shell and coral samples. Performance tests on the new YU-AMS system were carried out by measuring the C-series standard samples (C1-C9) and oxalic acid II (HOxII) obtained from IAEA and NIST, respectively. The results of the 〈sup〉14〈/sup〉C concentration pMC are in good agreement with the consensus values. Performance tests for medical applications were also carried out by measuring the 〈sup〉14〈/sup〉C concentration of 〈sup〉14〈/sup〉C-glucose in human plasma.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 440〈/p〉 〈p〉Author(s): R.A. Rymzhanov, S.A. Gorbunov, N. Medvedev, A.E. Volkov〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A swift heavy ion leaves a damaged trail (SHI track) while penetrating through a solid. The radius of the track depends on the ion energy loss and velocity, and thereby on its penetration depth. Applying developed Monte Carlo code TREKIS and molecular dynamics approach we describe the damage distribution along the trajectory of an SHI (Xe and U) in olivine. This enables us to obtain the dependencies of the track radius and structure on the ion energy and its energy losses, as well as to identify the track formation thresholds in forsterite (Mg〈sub〉2〈/sub〉SiO〈sub〉4〈/sub〉) for fast and slow ions. It is found that the position of the maximal damage produced by an ion in a solid does not coincide with the Bragg peak of its electronic stopping. Loop-like dependence of the track radius on the electronic energy loss is identified.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 438〈/p〉 〈p〉Author(s): P. Marshall, A. Bayliss, S. Farid, C. Tyers, C. Bronk Ramsey, G. Cook, T. Doğan, S.P.H.T. Freeman, E. İlkmen, T. Knowles〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This study tests whether accurate dating by AMS radiocarbon wiggle-matching short tree-ring series (c. 30 annual rings) in the period after AD 1510 can be achieved routinely. Such an approach has proved problematic for some intervals in the period AD 1160–1541 (Bayliss et al., 2017), which are before single-year calibration data are available (Stuiver, 1993). We suggest that such calibration data are essential if this approach is to be employed for the informed conservation of standing buildings.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 438〈/p〉 〈p〉Author(s): Carlos Vivo-Vilches, José María López-Gutiérrez, Manuel García-León, Christof Vockenhuber〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Dealing with the 〈sup〉41〈/sup〉K interference during 〈sup〉41〈/sup〉Ca measurement with low energy AMS systems is challenging. The detection of 〈sup〉39〈/sup〉K to correct the measured 〈sup〉41〈/sup〉Ca/〈sup〉40〈/sup〉Ca ratios is a powerful tool that improves precision and accuracy. However, the study of the sources of this interference can help to reduce it to its minimum.〈/p〉 〈p〉In this work, it is shown that iron is a factor enhancing the production of the 〈sup〉41〈/sup〉K interference, since the (〈sup〉41〈/sup〉K〈sup〉57〈/sup〉Fe)〈sup〉−〈/sup〉 ion has the same mass as (〈sup〉41〈/sup〉K〈sup〉19〈/sup〉F〈sub〉3〈/sub〉)〈sup〉−〈/sup〉. To validate this observation, we measured 〈sup〉57〈/sup〉Fe〈sup〉2+〈/sup〉 together with 〈sup〉41〈/sup〉M〈sup〉2+〈/sup〉 (all ions with mass 41) and 〈sup〉39〈/sup〉K〈sup〉2+〈/sup〉 in a blank sample and an aluminum target at the 600 kV AMS system at ETH Zurich.〈/p〉 〈p〉We also show the temporal evolution of 〈sup〉41〈/sup〉M/〈sup〉40〈/sup〉Ca and 〈sup〉39〈/sup〉K/〈sup〉40〈/sup〉Ca ratios in two blank samples during a measurement on the 1 MV AMS system at CNA Seville. Even when unstable behavior for these ratios is observed for one of the blanks, the relationship between both, 〈sup〉41〈/sup〉M/〈sup〉39〈/sup〉K, is relatively stable over time. This supports the accuracy of the K–correction method, providing that it is applied sequence by sequence.〈/p〉 〈p〉Two programs, one for each of these compact AMS systems, were written in FORTRAN code to deal with the complexity of the data analysis due to the K-correction.〈/p〉 〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 11 May 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): Jing Wang, Qiang Qi, Maoqiao Xiang, Shouxi Gu, Yingchun Zhang, Guang-nan Luo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In fusion reactors, Li〈sub〉2〈/sub〉TiO〈sub〉3〈/sub〉 is one of the most promising candidates among solid breeder materials. However, Li〈sub〉2〈/sub〉TiO〈sub〉3〈/sub〉 will be reduced after heating under a reducing atmosphere resulting in a deficiency of oxygen. In the present study, the O-related defects introduced by reduction and their effect on the release behavior of hydrogen isotopes in Li〈sub〉2〈/sub〉TiO〈sub〉3〈/sub〉 were investigated by means of Raman spectroscopy, electron spin resonance and thermal desorption spectroscopy. O-related defects were confirmed as E-centers by electron spin resonance. The concentration of defects increased as the exposing temperature increased and then decreased when the temperature increased higher above 750 °C. The color of Li〈sub〉2〈/sub〉TiO〈sub〉3〈/sub〉 samples changed from white to dark blue after heating under deuterium and recovered to white again after annealing in air. This color change suggested a change from Ti〈sup〉4+〈/sup〉 to Ti〈sup〉3+〈/sup〉 due to a decrease in the oxygen content. Raman spectroscopy results indicated that there are no modifications in Li〈sub〉2〈/sub〉TiO〈sub〉3〈/sub〉 crystal structure, but on crystallinity. Thermal desorption spectroscopy showed the release behavior of deuterium has been affected considerably by O-related defects.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 3 May 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): M. Saito, K. Holm, F.L. Bregolin, H. Hofsäss〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Herein, we describe new developments in the external coincidence elastic recoil detection analysis (coincidence ERDA) setup at the University of Göttingen. Our work aims to realize the quantitative evaluation of hydrogen in atmospheric pressure. The details of the developed device for the external coincidence ERDA, as well as the first spectra of the self-standing polymer foils are presented. We additionally prepared “wet” PVA foils with different water contents, and performed an external coincidence ERDA analysis. Using this setup, the increase in clear hydrogen and oxygen was observed as the foil contains more water. Since the external coincidence ERDA setup can offer greater flexibility for a variety of environments and the sample itself, this technique leads to a new method of moist sample characterization, and has potential for use in various 〈em〉in-situ〈/em〉/〈em〉operand〈/em〉 analyses.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 2 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): A. Dib, H. Ammi, M. Msimanga, S. Mammeri, C.A. Pineda-Vargas〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The slowing down of Cu, Si, Al and F heavy ions over the 0.09–0.51 MeV/nucleon energy range in thin Nickel (Ni) foil has been investigated by using the Heavy Ion Elastic Recoil Detection Analysis (HI-ERDA) technique coupled with a time of flight (ToF) spectrometer. This experimental setup generated a significant amount of energy loss data, which allowed the determination of stopping force of 〈sup〉63〈/sup〉Cu〈sup〉7+〈/sup〉 heavy ions in Nickel at low projectile energies. The obtained stopping force results were compared with semi-empirical calculations by Ziegler’s Stopping and Range of Ions in Matter (SRIM) code, and ab initio calculations by Grande and Schiewietz’s Convolution approximation for swift Particles (CasP) code. The aim of such comparison was to assess the reliability and accuracy of the existing energy loss formulations, in the light of the present experimental results. Good agreement was found between the experimental stopping force data for the reported ions velocities and SRIM predictions. For CasP, the agreement is fairly good from ∼0.15 MeV/n onwards.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 3 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): Fengfeng Luo, Jiawei Wang, Linwei Zhang, Liping Guo, Weiping Zhang, Zhenyu Shen, Chunlan Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The microstructure of bubbles induced by single-ion (He or H) and sequential-ion H/He irradiation in tungsten were investigated using transmission electron microscopy (TEM). Specimens were irradiated with 12 keV He〈sup〉+〈/sup〉 and 6.7 keV H〈sup〉+〈/sup〉 under different fluences at 600 °C. Bubbles were observed after single He〈sup〉+〈/sup〉 irradiation and sequential H〈sup〉+〈/sup〉/He〈sup〉+〈/sup〉 irradiation. Compared with single He〈sup〉+〈/sup〉 irradiation, the mean size of bubbles decreased first, and then increased with the increasing fluence of pre-implanted H〈sup〉+〈/sup〉 for the sequential H〈sup〉+〈/sup〉/He〈sup〉+〈/sup〉 irradiation condition. The main effect of pre-implanted H〈sup〉+〈/sup〉 with low proportion might enhance bubbles nucleated, and the main effect of pre-implanted H〈sup〉+〈/sup〉 with high proportion might make bubbles grow larger. The possible mechanism was discussed in this paper.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 441〈/p〉 〈p〉Author(s): M.C. Sulzbach, F.F. Selau, H. Trombini, P.L. Grande, G.G. Marmitt, L.G. Pereira, M. Vos, R.G. Elliman〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Oxygen self-diffusion was investigated in TiO〈sub〉2〈/sub〉 layers employed for resistive-switching memories using resonant nuclear reaction profiling (NRP) and 〈sup〉18〈/sup〉O labeling. The layers were grown using physical vapor deposition technique (sputtering) and were polycrystalline. The diffusivity was measured over the temperature range 600–800 °C and the activation energy for oxygen self-diffusion in sputter-deposited TiO〈sub〉2〈/sub〉 films determined to be 1.09 ± 0.16 eV, a value consistent with results obtained by previous studies (Marmitt et al., 2017).〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 3 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): Tamon Kusumoto, Morikazu Sakai, Atsushi Yoshida, Tadashi Kambara, Yoshiyuki Yanagisawa, Satoshi Kodaira, Keiji Oda, Masato Kanasaki, Koji Kuraoka, Rémi Barillon, Tomoya Yamauchi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We aim to determine the detection threshold of Kapton as an Etched Track Detector irradiated with 345 MeV/u U ion, as well as other several heavy ions of Al, Si, Ar, Kr and Xe. The heavier ions are found to have higher detection threshold in the stopping power. At the same stopping power, the track registration sensitivity decreases with increasing the nuclear charge of ions. U ion has the lowest sensitivity as 〈em〉S〈/em〉 = 0.04 at the detection threshold of 3400 keV/μm. We have updated the conventional radial dose distribution theory using a relatively new experimentally supported formula for the effective charge up to U ion. The local doses at a track radius of 0.8 nm, which is half of the length of a repeat unit of Kapton, is useful to understand the relation between the sensitivity of heavy ions and the stopping power at each detection threshold.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 3 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): G.U.L. Nagy, E. Giglio, I. Rajta, K. Tőkési〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Experimental observation of the dynamics of a micro-focused, 1 MeV proton beam guided through a single, insulating macrocapillary is presented. The micrometer sized proton beam was center injected into a poly(tetrafluoroethylene) capillary with macroscopic dimensions. The capillary was tilted to 1° with respect to the beam, i.e. no geometrical transmission was possible, but the beam first hit the inner capillary wall. After a sufficient electric charge-up of the insulator material due to the interaction with the charged particle beam, guiding appeared thanks to the beam deflection caused by the formed electrostatic field. With an increasing amount of the accumulated charge on the wall, the deflection of the beam also increased, resulting in the dynamics of the transmission. When a dynamical equilibrium between the charges being deposited and flowing away in form of leakage current was set in, the deflection of the beam saturated at a certain position. Here, the transmitted fraction of the beam reached 90% relative to the incident beam. At this position the angular distribution of the transmitted beam was determined. In the sample tilting plane focusing effect was observable, while in the perpendicular plane, the beam was defocused.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 2 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): Kyungsu Park, Jwa Soon Kim, Sung Yup An, Kwang Hwan Jung, Soobang Kim, Kyu-Sang Yu, Won Ja Min〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Quantitative hydrogen analysis is a useful tool in various fields, such as the energy, catalysts, and semiconductor fields, because the quality of materials or devices strongly depends on their hydrogen concentrations. To analyze the concentration of hydrogen quantitatively, the elastic recoil detection analysis (ERDA) method is widely used. In this report, the number fraction of hydrogen in silicon nitride was analyzed using a simple time-of-flight ERDA method over a depth range of 25 nm from the surface without the use of a stopping foil, an additional analyzer, or charged particle optics. The number fractions of the other elements (silicon and nitrogen) in the sample were also analyzed through backscattering measurements.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 440〈/p〉 〈p〉Author(s): Brahim Touchrift, Houria Salah, Nadjia Benouali, Abdehamid Ziane〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this contribution, the presence of vicinage effects is demonstrated for H〈sub〉2〈/sub〉〈sup〉+〈/sup〉 ions slowing down in 20 nm thick aluminium target, using the 1.735 MeV resonance of 〈sup〉12〈/sup〉C(p, p)〈sup〉12〈/sup〉C elastic scattering. The stopping power ratio is deduced from the measured Elastic Backscattering Spectrometry (EBS) energy spectra of H〈sup〉+〈/sup〉 and H〈sub〉2〈/sub〉〈sup〉+〈/sup〉 ions using the simulation code IBA DataFurnace. An enhancement of 30% is found in the energy loss of the H〈sub〉2〈/sub〉〈sup〉+〈/sup〉 ions as compared to the atomic ones. The influence of the Coulomb explosion on the energy loss straggling was also examined. This is evaluated for 100 nm thick target by adjusting the energy loss and the straggling parameters while processing the experimental data. A theoretical treatment, based on the Lindhard dielectric formalism generalized by N.R. Arista to molecular ions, was used to calculate the stopping power ratio for aluminium for comparison.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 440〈/p〉 〈p〉Author(s): Hongyang Cui, Rong Wang, Deqiang Wei, Jiayue Huang, Jinyan Guo, Xinkai Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The mechanical properties of materials surface are always the key elements to evaluate the performance of materials, which means the surface performance of materials plays a key role especially in some occasion. In this study, the performance of T8, T10 and T12 steel were evaluated by using continuous scanning electron beam process (CSEBP) method for surface modification. The microstructure and properties of the modified layer were studied, and the influence of the electron beam process parameters on the modified layer was discussed. Surface modification of the materials was carried out by varying the beam current of the continuous electron-beam irradiation procedure. Comparing with the initial surface roughness of materials, the ultimate surface roughness was reduced significantly, and which the optimal surface roughness appeared at the beam current of 6 mA. These were all because of the surface shallow melting (SSM). Microstructure, microhardness and wear resistance of materials surface and cross-section after treatment with different processing parameters are investigated by using scanning electron microscope, microhardness meter and universal wear tester. Finally, the influence law of electron beam processing parameters on the modification layer is summarized.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 440〈/p〉 〈p〉Author(s): V. Chudinov, I. Kondyurina, V. Terpugov, A. Kondyurin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Modern polyurethane elastomers are suitable materials for human implants. However, the immune system of an organism recognizes the polyurethane as a foreign body. A medical polyureaurethane, based on polyether, 2,4-toluenediisocyanate and aromatic diamine was treated by 20 keV nitrogen ions. The polyureaurethane surface was subsequently investigated by atomic force microscopy, electron spin resonance spectroscopy, Fourier transform infrared attenuated total reflection spectroscopy, wettability and surface energy analysis to observe the surface structure transformations associated with the ion implantation. The protein covalent attachment on the modified surface was observed. Endothelial cell attachment and proliferation showed preferences of the modified surface. Polyureaurethane samples were implanted into rats for 5 months. Histology data showed that the immune reaction to the modified polyureaurethane was weaker and the capsule wall is thinner for the modified polyureaurethane, than for the untreated polyureaurethane.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 439〈/p〉 〈p〉Author(s): Feng Liu, Chonghong Zhang, Chunqing He, Hai-Shan Zhou, Fang Ding, Guang-Nan Luo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Tungsten (W) foils were irradiated with 122 MeV 〈sup〉〈sub〉20〈/sub〉〈/sup〉Ne ions at the Heavy-ion Research Facility in Lanzhou, on which an energy degrader for tailoring the depth distribution of implanting ions was used. SRIM calculation showed that a quasi-homogeneous distribution of atomic displacement damage to 0.16 dpa within a depth of 50 μm was produced in W. The features of radiation damage were characterized with positron annihilation life spectroscopy (PALS) and transmission electron microscopy (TEM) techniques in this study. Results from PALS study indicated that large vacancy clusters characterized by a long positron lifetime component of ∼510 ps were formed in the irradiated W. These clusters may be the nano-voids (an average diameter of ∼1 nm) exhibited in TEM imaging. Radiation-induced dislocation loops were also observed. Both perfect and Frank loops were manifested under the high resolution TEM observation. The experimental observation of a/2〈1 1 0〉 faulted loops in irradiated W was somewhat surprising and it may shed light on the origin of dislocation formation and their evolution in irradiated bcc metals.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 439〈/p〉 〈p〉Author(s): G. Laricchiuta, W. Vandervorst, J. Meersschaut〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Rutherford backscattering spectrometry (RBS) is an analysis method to quantify reference free the atomic areal density of a thin film, in particular sensitive to those cases where the elements of the film are heavier than the substrate. The ultimate sensitivity is determined by the ratio between the signal intensity from the thin film and the background signal originating from e.g. pulse pile-up events related to the scattering from the substrate atoms or dark noise intrinsic to the detector. We demonstrate that the sensitivity of RBS can be improved by reducing the pulse pile-up and dark noise background through the implementation of a magnet sector and a silicon strip detector as combined double energy dispersive analyzer. A limit-of-detection of 3∙10〈sup〉11〈/sup〉 Ru/cm〈sup〉2〈/sup〉 on Si is achieved.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 439〈/p〉 〈p〉Author(s): A. Hosseini, M.N. Nasrabadi, A. Esfandiarpour〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this research, in order to investigate primary radiation damage in iron nanofoam, simulation of displacement cascade near cylindrical nanovoids is performed using molecular dynamics. A primary knocked-on atom with 3, 6 and 9 keV energies and velocity parallel to the cylinder axis at 300 K is considered. 1–4 nanovoids are used as the model structure for free surfaces. It is identified that interaction between the displacement cascades and free surfaces is very sensitive to PKA energy and the distance of free surfaces. Near-surface cascade mechanism is observed when the displacement cascade interacts with a single cylindrical free surface, where clusters of bulk vacancies and a rim of adatoms are formed. In this case, based on the location of these defects rather free surface, two sub-mechanisms are identified. It is recognized that the degree of the penetration of the cascade into the cylindrical surfaces, plays an important role in forming vacancies and vacancy clusters in the ligament after the cooling of the cascade. Results show that when the PKA energy is 9 keV, enhancement of number of nanovoids increases the number of vacancies in the bulk. In this case, formation of vacancy planes is observed between the cylindrical nanovoids. The absorption of bulk vacancy clusters by the free surfaces is observed when displacement cascade is generated by a 6 keV PKA in close vicinity of four cylindrical surfaces.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 440〈/p〉 〈p〉Author(s): Y. Sasajima, N. Ajima, R. Kaminaga, N. Ishikawa, A. Iwase〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the present paper, we have extensively analyzed the atomic structures generated by supplying a thermal spike to the single crystal CeO〈sub〉2〈/sub〉 that we previously analyzed for specimens by the molecular dynamics method [Y. Sasajima et al., Nucl. Instr. Meth. B 314 (2013) 202]. Our analysis results were compared with the atomic structures obtained by the actual experiments using HAADF-STEM and ABF-STEM [S. Takaki et al., Nucl. Instr. Meth. B 326 (2014) 140]. Our simulation results and the experimental observations agreed well on the following point that the lattice of cerium is maintained while oxygen atoms migrate from their equilibrium cites. In particular, our simulation reproduced the distribution of the numbers of oxygen atoms obtained from the analysis of TEM images. The detailed process of generation and elimination of vacancies has also been analyzed as a function of time. We found that the number of vacancies was increased abruptly immediately after the thermal spike, and the number subsequently dropped through a relaxation process within 3 ps.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 440〈/p〉 〈p〉Author(s): Indudhar Panduranga Vali, Pramoda Kumara Shetty, M.G. Mahesha, V.G. Sathe, D.M. Phase, R.J. Choudhary〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this paper, the gamma irradiation effects on the structural and optical properties of N-doped 4H-SiC (n-4H-SiC) is presented up to a cumulative gamma radiation dose of 1500 kGy. The studies showed marginal and inconsistent variation in the 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si5.gif" overflow="scroll"〉〈mi〉c〈/mi〉〈/math〉- and 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si6.gif" overflow="scroll"〉〈mi〉a〈/mi〉〈/math〉-axis lattice constants of 4H-SiC due to the accumulation of gamma-induced defect states. The modifications in the longitudinal optical plasmon-phonon coupled (LOPC) modes, Biedermann absorption bands, Urbach energy (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si7.gif" overflow="scroll"〉〈msub〉〈mi〉E〈/mi〉〈mi〉U〈/mi〉〈/msub〉〈/math〉) and defect related photoluminescence (DPL) bands are discussed at different (500, 1000 and 1500 kGy) irradiation doses. Despite these effects, the overall gamma-induced disorder (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si3.gif" overflow="scroll"〉〈msub〉〈mrow〉〈mn〉1〈/mn〉〈mo〉-〈/mo〉〈mi mathvariant="normal"〉A〈/mi〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉n〈/mi〉〈mi mathvariant="normal"〉o〈/mi〉〈mi mathvariant="normal"〉r〈/mi〉〈mi mathvariant="normal"〉m〈/mi〉〈/mrow〉〈/msub〉〈/math〉) and variation in the free carrier concentrations (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si4.gif" overflow="scroll"〉〈mi〉n〈/mi〉〈/math〉) are found to be negligible and demonstrating the radiation resistant property of n-4H-SiC under gamma radiation environment.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 439〈/p〉 〈p〉Author(s): Tetsuya Matsunaka, Kimikazu Sasa, Tsutomu Takahashi, Seiji Hosoya, Masumi Matsumura, Yukihiko Satou, Shen Hongtao, Keisuke Sueki〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To evaluate the environmental impact of 〈sup〉14〈/sup〉C discharged to the atmosphere from the Tokai nuclear facility during normal operational periods, cores were extracted from an 80-yr-old pine tree that grew close to the Tokai Nuclear Power Plants (Tokai NPP and Tokai-2 NPP) and the Tokai Reprocessing Plant (Tokai RP), and the 〈sup〉14〈/sup〉C levels in the annual rings were measured using accelerator mass spectrometry (AMS). The 〈sup〉14〈/sup〉C activity ranged from 232 to 403 Bq kg〈sup〉−1〈/sup〉 C in the tree rings formed during the period 1959–2013. The activities in the periods 1959–1965 and 2011–2013 represent the background levels, and the activities recorded between 1966 and 2010 are significantly elevated compared with these background levels, indicating uptake by the tree of 〈sup〉14〈/sup〉C discharged from the Tokai nuclear facility. The excess 〈sup〉14〈/sup〉C activity values of 1.1–70 Bq kg〈sup〉−1〈/sup〉 C for the period 1966–2010 are positively correlated with the estimated total annual 〈sup〉14〈/sup〉C discharges of 0.019–2.0 TBq from the Tokai NPP, Tokai-2 NPP, and Tokai RP (R〈sup〉2〈/sup〉 = 0.72; n = 40). This activity of 〈70 Bq kg〈sup〉−1〈/sup〉 C corresponds to an additional annual effective dose to the local population, via the food ingestion pathway, of less than 3.9 µSv yr〈sup〉−1〈/sup〉. These values are negligible compared with the average natural background radioactive dose in the world.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 440〈/p〉 〈p〉Author(s): L. Campajola, S. Braccini, P. Casolaro, D. de Luca, A. Ereditato, P.D. Häffner, P. Scampoli〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉For the first time the Rutherford Back-Scattering Spectroscopy (RBS) technique has been successfully exploited for the measurement of the energy of a proton beam accelerated by the IBA Cyclone 18/18 medical cyclotron in operation at the Bern University Hospital. This accelerator, routinely used for radioisotope production for Positron Emission Tomography (PET) imaging is equipped with an external beam line devoted to research activities in several fields such as detector physics, medical applications of particle physics, accelerator physics. Recently a widespread request has raised for the availability of well characterized proton and neutron beams, particularly for radiation hardness studies and the development of new neutron detectors. A feasibility study for a future upgrade of the Bern cyclotron towards a neutron facility was started, which requires a complete and precise characterization of the proton beam. Along this line, the measurement of fundamental parameters of the primary proton beam, such as the maximum proton energy and its spread have been performed by means of the RBS technique with two different targets, namely gold and graphite foils.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 440〈/p〉 〈p〉Author(s): Shengli Chen, David Bernard〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Displacement per Atom (DPA) is one of the most important factors that influence the mechanical behaviors of materials during and after irradiation. However, the relativistic effect is not accounted for in typical calculations of DPA cross sections and Primary Knock-on Atom (PKA) spectra. The present work shows the computation of relativistic recoil energy. For incident energy lower than 20 MeV, the relativistic corrections are within 1% for neutron scattering reactions of 〈sup〉56〈/sup〉Fe and nuclei with mass larger than 〈sup〉56〈/sup〉Fe. The corresponding corrections on damage energy (equivalent to DPA with standard DPA metrics) is smaller than 0.5%. However, the relativistic effect is of importance for high incident energies, such as 200 MeV. For example, the relativistic recoil energy of continuum inelastic scattering is 10% higher than the classical one for all nuclei. The consideration of relativistic effect increases the recoil energy for the elastic scattering. Both positive and negative relativistic corrections are possible for both discrete and the inelastic scatterings. A consequent result is the broadening of PKA spectra.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 14 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms〈/p〉 〈p〉Author(s): P. Sigmund, V. Kuzmin, A. Schinner〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Reciprocity denotes the (approximate) equality of the electronic stopping cross section of element A in element B with the one of element B in element A. Reciprocity is expected in the energy range below 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si7.gif" overflow="scroll"〉〈mrow〉〈mo〉∼〈/mo〉〈mn〉0.1〈/mn〉〈/mrow〉〈/math〉 MeV/u. For ions heavier than protons, most measurements are performed by the transmission technique. In order to minimize nuclear energy loss, only a narrow beam of penetrating ions is allowed to enter the detector. This implies that also the electronic energy loss is underestimated. We have estimated the magnitude of the necessary correction on the basis of the PASS code and its influence on the expected reciprocity and find that reciprocity is not necessarily violated, even if the reported cross sections differ significantly. However, we also find differences between reported stopping cross sections and computed reduced stopping cross sections that we cannot reconcile on the basis of the PASS code. These differences are found to reflect the well-known 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si4.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mrow〉〈mi〉Z〈/mi〉〈/mrow〉〈mrow〉〈mn〉1〈/mn〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 structure, which is not inherent in the present version of PASS.〈/p〉〈/div〉 〈/div〉