ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Publication Date: 2016-06-07
    Description: The cosmogenic radionuclides Be(10), Al(26), and Mn(53) and noble gases were determined in more than 28 meteorites from Antarctica by nuclear analytical techniques and static mass spectrometry, respectively. The summarized results are listed. The concentrations of Al(26) and Mn(53) are normalized to the repective main target elements and given in dpm/kg Si sub eq and dpm/kg Fe. The errors stated include statistical as well as systematical errors. For noble gas concentrations estimated errors are 5% and for isotopic ratios 1.5%. Cosmic ray exposure ages T sub 21 were calculated by the noble gas concentrations and the terrestrial residence time (T) on the basis of the spallogenic nuclide Al(26). The suggested pairing of the LL6 chondrite RKPA 80238 and RKPA 80248 and the eucrites ALHA 76005 and ALHA 79017 is confirmed not only by the noble gas data but also by the concentrations of the spallation produced radionuclides. Futhermore, ALHA 80122, clasified as an H6 chondrite, has a noble gas pattern which suggest that this meteorite belongs to the ALHA 80111 shower.
    Keywords: SPACE RADIATION
    Type: Lunar and Planetary Inst. International Workshop on Antarctic Meteorites; p 55-57
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Publication Date: 2016-06-07
    Description: The concentrations of cosmogenic nuclides were studied as a function of shielding on samples from a cross section of the 293 kg main fragment of the L5 chondrite Knyahinya. The stone broke into two nearly symmetrical parts upon its fall in 1866. The planar cross section has diameters between 40 and 55 cm. He, Ne, and Ar were measured on about 20 samples by mass spectrometry and the 10-Be activities on aliquots of 10 selected samples were determined by AMS. The 10-Be data are presented and the abundances of spallogenic nuclides are compared with the model calculations reported by Reedy for spherical L chondrites. The 10-Be production rates in Knyahinya are shown versus the shielding parameter 22-Ne/21-Ne.
    Keywords: ASTROPHYSICS
    Type: Lunar and Planetary Inst. Workshop on Cosmogenic Nuclides; 1 p
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Publication Date: 2011-08-24
    Description: The existence of microbial communities living inside desert rocks has been reported by FRIEDMANN et al. (1967, 1976), first in rocks collected from the hot and dry Negev desert and later in rocks in the frigid Ross Desert of Southern Victoria Land, Antarctica. The extremely inhospitable climatic conditions in both places has led to the suggestion that these organisms have very low rates of metabolism and may, in addition, be very old (FRIEDMANN 1982). Our preliminary measurements showed a 14C deficiency indicating a carbon age in the order of magnitude of 10(3) years.
    Keywords: Exobiology
    Type: Polarforschung (ISSN 0032-2490); Volume 58; 2-3; 199-200
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Publication Date: 2011-08-19
    Description: The terrestrial age of a meteorite that was recovered from below the surface of Antarctic ice is reported, and it is argued that this represents a measurement of the age of the ice itself. The cosmogenic radionuclides Be-10, C-14, Al-26, Cl-36, and Mn-53 are measured in the meteorite and Be-10 and Cl-36 in the ice. A terrestrial age of 11,000 yr is obtained for the meteorite, which suggests that the snow accumulation area where it fell was only a few tens of km away.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature (ISSN 0028-0836); 340; 550-552
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Publication Date: 1986-09-01
    Description: In this paper we present accelerator radiocarbon measurements on hand picked benthic and planktonic foraminifera separated from two deep sea cores raised from the South China Sea. From the benthic-planktonic age differences we are able to place limits on the extent to which the ventilation rate of the deep Pacific Ocean has changed over the last 12000 years. While much work remains to be done before any definitive answers for the global oceans can be given, these results on cores with sedimentation rates suitably high to avoid major corrections for bioturbation effects suggest that the ventilation rate of the deep Pacific Ocean has remained nearly the same throughout Holocene time. Further, there is no suggestion that the rate was slower during the period of major glacial retreat. These results confirm that the changes in atmospheric14C/C ratio over the last 10000 years owe their origin to radiocarbon production rate changes. ©1986 Springer-Verlag
    Print ISSN: 0930-7575
    Electronic ISSN: 1432-0894
    Topics: Geosciences , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Publication Date: 1989-10-01
    Description: Manganese nodules from the Kane Gap (a deep sea channel connecting the Sierra Leone and Gambia Basins off West Africa) were investigated chemically and dated by10Be along cross-sections. Comparing the nodule structure with the stratigraphy of the related sediments, the following conclusions are drawn concerning the sedimentation processes during the last 4 to 6×106 years: The growth of the nodules started about 4 to 4.5 Ma before present during or near to the end of a period of erosion on a fossil-free, probably Miocene sediment. During the first phase of only a few hundred thousandyears, the nodules grew very quickly (7 to 〉18 mm/Ma). Fe-rich hydrogenetic material formed the internal sections of the nodules during this time. Slowing down of the bottom currents, resulting in deposition of thin sediment covers for short intervals, caused the character of the nodules to change to a more diagenetic composition. The growth rates were reduced to about 1 to 2 mm/Ma. The time of slowing is roughly 3 to 4 Ma BP. Probable uncertainties of the dating and growth rates resulting from supposed changes of the10Be supply to the nodules due to variations of the near bottom environment are discussed.RésuméLe «Kana Gap» est un chenal sous-marin qui relie les bassins de Sierra Leone et de Gambie, au large de l'Afrique occidentale. Des nodules de manganèse, recueillis le long de profils transversaux dans ce chenal, ont fait l'objet d'une étude chimique et d'une détermination d'âge10Be. La comparaison entre la structure des nodules et la stratigraphie des sédiments sous-jacents permet de tirer les conclusions suivantes relatives au processus sédimentaire au cours des 4 à 6 derniers Ma. La croissance des nodules a commencé il y a environ 4 à 4,5 Ma pendant ou juste après un épisode d'érosion sous-marine sur des sédiments non fossilifères, probablement miocènes. Au cours d'une première phase d'une durée de quelques centaines de milliers d'années, la croissance a été très rapide (7 à 〉 18 mm par Ma) avec formation de la partie centrale du nodule, constituée de matière hydrogénée riche en Fe. Ensuite, après ralentissement des courants de fond et dépôt probable d'une mince couche de sédiment, le caractère des nodules a évolué vers une composition plus diagénétique, avec réduction du taux de croissance à 1 à 2 mm par Ma. Le moment de ce changement de régime doit se situer entre 3 et 4 Ma. Des changements dans les conditions de milieu sur le fond de la mer pourraient avoir provoqué une variation de la quantité de10Be apportée aux nodules, d'où résulterait une incertitude sur l'estimation des âges et du taux de croissance; cette question est discutée par les auteurs.ZusammenfassungAn Manganknollen aus der Kane-Lücke, dem Verbindungskanal zwischen Sierra Leone Becken und Gambia Becken (vor W-Afrika) wurden entlang Querprofilen durch mehrere Knollen chemische Untersuchungen und10Be Altersbestimmungen durchgeführt. Durch Vergleich des Aufbaus der Knollen mit der Stratigraphie des unterlagernden Sediments werden Rückschlüsse auf Veränderungen des Sedimentationsgeschehens während der letzten 4–6×106 Jahre gezogen. Hiernach begann das Wachstum der Knollen vor maximal 4.5×106 Jahren während oder gegen Ende einer Erosionsphase auf fossilfreiem, vermutlich miozänem Sediment. Während der ersten Phase wuchsen die Knollen über wenige 100000 Jahre sehr schnell (7 bis〉18 mm/106 Jahre). Hierbei schied sich Fe-reiche Knollensubstanz hydrogener Zusammensetzung ab. Nach Verringerung der Strömung und vermutlich zeitweiser Bildung von dünnen Sedimentschleiern änderte sich der Charakter der Knollen zu mehr diagnetischer Zusammensetzung bei wesentlich reduziertem Wachstum (ca. 1 bis 2 mm/106 Jahre). Der Zeitpunkt der Umstellung ist nur sehr grob zu ermitteln, er dürfte etwa zwischen 3 und 4×106 Jahren vor heute liegen. Eventuelle Unsicherheiten bei der Datierung und den Wachstumsraten, die möglicherweise aus milieubedingten Änderungen in der10Be Versorgung der Knollen resultieren, werden diskutiert.Краткое содержаниеПровели химические и сследования и опреде лили возраст по10Ве марган цевых желваков, отобр анных вдоль поперечного пр офиля в проливе Кана, к оторый является каналом, сое диняющим бассейны Си ерры Леоне и Гамбии перед п обережьем западной А фрики. Сопоставление струк туры желваков и страт играфии подстилающих седиме нтов разрешило сдела ть вывод, что во время последни х 4х106–6×106 лет имели мест о изменения в процесса х седиментации. Рост ж елваков начался, самое раннее 4,5х106 лет тому назад во время и в конце эрозио нной фазы седимента, в ероятно, миоценового возраст а, свободного от фосси лий. Во время первой фазы ж елваки в течение неск ольких 100.000 лет росли очень быст ро: 7 до 18 мм за Ма. При этом образовалась ги дрогенная, богатая же лезом субстанция желваков. Когда течение измени лось, началось временное образован ие тонкослойных осад очных покровов, и характер ж елваков также измени лся в сторону биогенетич еского состава при бо лее замедленном росте их: от 1 до 2 мм за Ма. Время такого преобразования можн о установить только приблизительно, оно должно относится к периоду 3х106–4х 106 лет тому назад. Обсуждаются возможн ые неточности датиро вки и определения скорост и роста, которые, возмо жно, обусловлены изменен ием среды, из которой10Ве попадал в желваки. ©1989 Ferdinand Enke Verlag Stuttgart
    Print ISSN: 1437-3254
    Electronic ISSN: 1437-3262
    Topics: Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A thick spherical target (R=25 cm) made of gabbro was irradiated isotropically with 1.6 GeV protons at the Saturne cyclotron at Laboratoire National Saturne (LNS)/CEN Saclay in order to simulate the interaction of galactic cosmic ray (GCR) protons with meteoroids in space. During a 2 weeks irradiation a proton-dose of 1.32 · 1014 cm−2 was received, which is equivalent to a cosmic-ray exposure age of 1.4 Ma. Production rates were measured by X- and gamma-spectrometry, by low-level counting and by conventional and accelerator mass spectrometry (AMS). Up to now, more than 200 target-product combinations were investigated. Theoretical production rates were derived on the basis of spectra of primary protons, secondary protons and secondary neutrons calculated by Monte Carlo techniques and thin-target cross sections of the underlying nuclear reactions. The model calculations excellently describe the production depth profiles in the artificial meteoroid, if reliable crosss sections are available. The thus validated model calculations allow for the interpretation of cosmogenic nuclide abundances in stony meteorites and lunar samples in terms of their exposure history and of the history of the radiation itself.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Anisotropy spectra of the MOK X-ray transitions have been measured in F-Al, Al-Al and Cl-Al collisions as a function of the projectile energy. The measurements at higher energies indicate a new molecular effect due to transitions from quasicontinuum states to the MO 1s σ-orbitals.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The anisotropies of the MO-2pσ-radiation have been measured for five symmetric systems with a united atom numberZ u between 52 and 94 at beam energies in the range from 7 up to 66 MeV. A comparison with the available theoretical data suggests that the anisotropic part of the 2pσ-radiation is mainly due to transitions from near continuum initial states into the minimum of the molecular 2pσ-orbital.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The dependence of molecular X-ray emission on the azimuthal angle in heavy ion collisions has been measured as a function of the impact parameter in the collision systems F-Al and Cl-Cl at projectile energies of 20 and 48 MeV respectively. The values of the observed azimuthal anisotropies agree with dynamical calculations of molecular orbital X-ray emission, but they are at variance with predictions of the kinematic dipole model.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...