ALBERT

Description: In-field calibration of the Navigation Dosimetry System (NAVIDOS) during solar minimum conditions T. Möller, O. Burda, S. Burmeister, B. Heber, F. Langner, and F. Wissmann Astrophys. Space Sci. Trans., 8, 45-49, doi:10.5194/astra-8-45-2012, 2012 The NAVIgation DOsimetry System (NAVIDOS) comprises a complete readout system for a radiation detector, an air pressure sensor and a GPS receiver. The detector system DOSTEL uses silicon detectors which make NAVIDOS light weighted and compact in size. Therefore, NAVIDOS is well suited to be installed on board aircraft. The calibration of NAVIDOS in terms of ambient dose equivalent is done by an in-field comparison with the PTB reference instrument πDOS. We also show that the dependence of these results on the vertical cut-off rigidity can be explained by the low response of the silicon detectors for neutrons. Therefore, in-flight measurements have been performed together with the PTB reference instrument πDOS. The dose rates, calculated using the PTB code FDOScalc, were verified with these πDOS measurements. The calibration of NAVIDOS was done with FDOScalc and results in calibration factors between 3.4 in the polar and 2.4 in the equator region.

Description: Helium counters for low neutron flux measurements Z. Dębicki, K. Jędrzejczak, J. Karczmarczyk, M. Kasztelan, R. Lewandowski, J. Orzechowski, B. Szabelska, J. Szabelski, P. Tokarski, and T. Wibig Astrophys. Space Sci. Trans., 7, 511-514, doi:10.5194/astra-7-511-2011, 2011 We present a comparison of some characteristics of helium counters for measurements of low intensity neutron flux. We focus on neutron flux density measurements in low background laboratories. Because of an extremely low counting rate (few events per hour or less), we have concentrated on counter parameters which are sometimes meaningless under regular conditions, i.e. background from internal alpha radioactivity, percentage of events in full energy peak, and the width of this peak. The background depends on residual radioactivity of the counter tube material and can not be eliminated. The full energy peak characteristics can be specified by counter gas composition. We will present a comparison of four types of helium gas counters.

Description: A method for real-time GLE modeling E. V. Vashenyuk Astrophys. Space Sci. Trans., 7, 453-458, doi:10.5194/astra-7-453-2011, 2011 By now real time systems of data collection of neutron monitor network have been created. The main goal of such systems is early detection of dangerous events of space weather, such as GLE, caused by arrival to the Earth of relativistic solar protons. Characteristics of these particles are determined from the data of the worldwide neutron monitor network by methods of GLE modeling. Traditional GLE modeling requires data of no less than 30–35 stations and takes a long time of computations. We developed a truncated technique of solar proton spectrum determination by data of limited number (20–25) of neutron monitor stations and with a simplified procedure of computations adapted for operative diagnostics of relativistic solar protons just arriving to the Earth. Possibilities of this truncated GLE modeling for the early forecast of radiation-dangerous fluxes of solar particles with moderate energies are also shown.

Description: EAS hadronic component as registered by a neutron monitor Yu. V. Balabin, B. B. Gvozdevsky, E. V. Vashenyuk, and D. D. Dzhappuev Astrophys. Space Sci. Trans., 7, 507-510, doi:10.5194/astra-7-507-2011, 2011 For the purposes of a study of hadron component of an extended air shower (EAS), two detectors of cosmic rays (CR) were joined at the Baksan Neutrino Observatory. They are an EAS array detector (the "Carpet") and a neutron monitor (NM). Due to the versatility of a new recording system a master-pulse, which comes from the "Carpet" and marks to occurring of EAS, is joined to NM data. After processing of the huge data set it is found that the time of EAS influence on NM is less than 1 ms. The distribution of time intervals between pulses in the first millisecond after EAS onset is essentially different from the background and shows presence of two processes with characteristic times 45 and 230 μs.

Description: The effect of cosmic rays on biological systems – an investigation during GLE events N. K. Belisheva, H. Lammer, H. K. Biernat, and E. V. Vashenuyk Astrophys. Space Sci. Trans., 8, 7-17, doi:10.5194/astra-8-7-2012, 2012 In this study, first direct and circumstantial evidences of the effects of cosmic rays (CR) on biological systems are presented. A direct evidence of biological effects of CR is demonstrated in experiments with three cellular lines growing in culture during three events of Ground Level Enhancement (GLEs) in the neutron count rate detected by ground-based neutron monitor in October 1989. Various phenomena associated with DNA lesion on the cellular level demonstrate coherent dynamics of radiation effects in all cellular lines coincident with the time of arrival of high-energy solar particles to the near-Earth space and with the main peak in GLE. These results were obtained in the course of six separate experiments, with partial overlapping of the time of previous and subsequent experiments, which started and finished in the quiet period of solar activity (SA). A significant difference between the values of multinuclear cells in all cellular lines in the quiet period and during GLE events indicates that the cause of radiation effects in the cell cultures is an exposure of cells to the secondary solar CR near the Earth's surface. The circumstantial evidence was obtained by statistical analysis of cases of congenital malformations (CM) at two sites in the Murmansk region. The number of cases of all classes of CM reveals a significant correlation with the number of GLE events. The number of cases of CM with pronounced chromosomal abnormalities clearly correlates with the GLE events that occurred a year before the birth of a child. We have found a significant correlation between modulations of the water properties and daily background variations of CR intensity. We believe that the effects of CR on biological systems can be also mediated by fluctuations in water properties, considered as one of possible mechanisms controlling the effects of CRs on biological systems.

Description: A Shannon entropy approach to the temporal evolution of SEP energy spectrum M. Laurenza, G. Consolini, M. Storini, and A. Damiani Astrophys. Space Sci. Trans., 8, 19-24, doi:10.5194/astra-8-19-2012, 2012 The kinetic energy spectra of solar energetic particle (SEP) events contain information on the particle acceleration mechanisms. A novel approach is proposed to investigate the time evolution of the spectral shape for the 20 February 2002 SEP event. Proton differential fluxes recorded by the ERNE instrument aboard SOHO, in the energy range 1.67–112 MeV, are analyzed. The solar source is associated with this SEP event by studying solar and interplanetary conditions during the considered time period. The energy spectrum evolution is studied by evaluating the time history of Shannon's differential entropy derived from the SEP fluxes. Our findings suggest that particle acceleration in the considered event is produced by a perpendicular shock in the solar corona. Moreover, dropouts in the particle flux are clearly identified up to energies of at least ~10 MeV.

Description: Features of relativistic solar proton spectra derived from ground level enhancement events (GLE) modeling E. V. Vashenyuk, Yu. V. Balabin, and B. B. Gvozdevsky Astrophys. Space Sci. Trans., 7, 459-463, doi:10.5194/astra-7-459-2011, 2011 With the developed by the authors of a ground level enhancements events (GLE) modeling technique, the modeling study of 35 large GLEs for the period 1956–2006 has been carried out. The basic characteristics of relativistic solar protons (RSP) are obtained: a rigidity (energetic) spectrum, anisotropy axis direction, and pitch angle distributions for each event. It is shown that in nearly all events there existed two components (population) of relativistic solar particles: prompt and delayed. The prompt component (PC) prevails in the beginning of the event. It is characterized by an impulsive profile, strong anisotropy and exponential energetic spectrum. The delayed component (DC) dominates during maximum and decline phases of the events. It has a gradual intensity profile, moderate anisotropy and a power law energetic spectrum. The analysis of the large number GLE shows the value of a characteristic energy in the exponential spectrum of PC has rather stable meaning ~0.5 GeV and well agrees with the spectrum of protons accelerated in an electric field arising during the magnetic reconnection in the solar corona. The value of a spectral exponent of the power law spectrum of DC is distributed from 4 up to 6 with most at 5. This is close to the simulated spectrum arising in the process of stochastic acceleration in turbulent solar plasma.

Description: On the energy spectrum of cosmic ray muons in 100 TeV region Yu. F. Novoseltsev, A. G. Bogdanov, R. P. Kokoulin, R. V. Novoseltseva, V. B. Petkov, and A. A. Petrukhin Astrophys. Space Sci. Trans., 7, 483-486, doi:10.5194/astra-7-483-2011, 2011 The energy spectrum of cosmic ray muons in the energy range from several TeV to ~1 PeV obtained by means of the analysis of multiple interactions of muons (pair meter technique) in the Baksan underground scintillation telescope is presented. Some evidence for the additional muon flux (to the conventional one from pion and kaon decays) has been obtained at energies ~100 TeV.

Description: High-energy photons connected to atmospheric precipitations A. V. Germanenko, Yu. V. Balabin, E. V. Vashenyuk, B. B. Gvozdevsky, and L. I. Schur Astrophys. Space Sci. Trans., 7, 471-475, doi:10.5194/astra-7-471-2011, 2011 Increases in intensity of X-radiation in the ground layer of the atmosphere observed during various atmospheric phenomena in two points: Apatity (Kola Peninsula) and Barentsburg (Spitsbergen) have been studied. A clear relationship between the increases and such atmospheric phenomena as rain and snowfall has been found. It is shown that these increases are not connected with any radionuclides. This research suggests that the principal cause of high-energy photons increase during precipitations are bremsstrahlung X -rays created by energetic electrons accelerated by electric fields in the clouds. A possible mechanism of generation of X -ray photons is discussed.

Description: An explanation of the Pioneer anomaly involving accelerated atomic clocks K. Wilhelm and B. N. Dwivedi Astrophys. Space Sci. Trans., 7, 487-494, doi:10.5194/astra-7-487-2011, 2011 The Pioneer anomaly stands for unexplained frequency shifts of the Doppler radio-tracking signals received at the ground stations from the Pioneer 10 and 11 spacecraft in disagreement with expectations based on model calculations. We consider here observations of Pioneer 10 at heliocentric distances between 40 ua and 70.5 ua over a time interval of 11.55 years from 1987 to 1998. The anomaly has been interpreted in the literature either as a Doppler shift caused by an apparent spacecraft deceleration not accounted for by known effects, or as an unexpected clock acceleration of the frequency standards at the ground stations. The reasons for the anomalous behaviour are not understood in both cases. Based on a gravitational impact model – requiring a secular mass increase of all massive bodies – a solution is proposed that implies a clock acceleration with a value close to that of the Hubble constant.