Results 51 to 60 of about 92 (70)
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International meeting for geochronology, cosmochronology and isotope geology
Geochimica Et Cosmochimica Acta, 1974exaly +2 more sources
Ages from Nuclear Cosmochronology
1986The long-lived radio nuclides 187Re, 232Th, 238U, 235U, and 244Pu can be used to set limits on the galactic age. The interpretation depends on (1) the production ratios of these isotopes in the appropriate nucleosynthesis site, (2) the time-dependent nucleosynthesis rate during galactic evolution, and (3) the isotopic ratios in the matter which ...
F.-K. Thielemann, J. W. Truran
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Photoneutron cross section measurements on 186W, 187Re and 188Os for cosmochronology
Nuclear Physics A, 2005Cross sections of the 186W, 187Re, 188Os(γ,n) reactions were measured using quasi monochromatic γ-ray beams from laser Compton scattering (LCS), and results for the latter reaction are presented here. Neutron capture cross sections of the inverse reactions were evaluated by the Hauser-Feshbach statistical calculation where the experimental data were ...
Shizuma, Toshiyuki +9 more
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Testing white dwarf cosmochronology using wide double white dwarfs
Proceedings of the International Astronomical Union, 2019AbstractWe present a sample of nearly 650 widely separated double white dwarf binaries found using Gaia DR2 astrometry. We derive preliminary total ages for each white dwarf in our sample using Gaia photometry and compare the total ages of both components of each binary in our sample.
Tyler Heintz, JJ Hermes
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On The β-Decay of 187 Re: An Interface of Atomic And Nuclear Physics And of Cosmochronology
1989Publisher Summary This chapter discusses how a study of the ratios of various isotopes of Re and Os combined with a knowledge of the half-life T 1/2 of the β decay of 187 Re can be helpful in estimating the age of our galaxy. The chapter defines or expands on astrophysical terminology and concepts and which emphasizes the broad view of the ...
Zonghua Chen +2 more
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White dwarf cosmochronology and M4
2004We discuss the accuracy of the present theoretical models of white dwarfs (WDs). We find that for ages higher than about 6-7 Gyr, the uncertainty in the predicted cooling times is of the order of 25%. The bulk of this uncertainty is due to the chemical profile in the Carbon/Oxygen core and the treatment of the conductive opacity. As a first application
PRADA MORONI, PIER GIORGIO +4 more
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The evaluation of half-lives and other decay data used in nuclear astrophysics and cosmochronology
Physics of Atomic Nuclei, 2011The current status of some decay data used in nuclear astrophysics and cosmochronology is presented. The half-life of 79Se has been evaluated as 3.6(3) × 105 yr. The total energy of non-neutrino radiation released in act of 37Ar decay has been obtained being 2.709 (16) keV per disintegration.
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Earth and Planetary Science Letters, 2000
Abstract Acapulcoites consistently yield some of the oldest 40Ar/39Ar ages reported for any meteorites, all indistinguishable from the age of 4510±22 Ma previously determined for whole-rock samples of Acapulco. These ages are significantly younger, at face value, than the 4557±2 Ma Pb/Pb age reported for phosphates, which dates cooling through ∼550°C.
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Abstract Acapulcoites consistently yield some of the oldest 40Ar/39Ar ages reported for any meteorites, all indistinguishable from the age of 4510±22 Ma previously determined for whole-rock samples of Acapulco. These ages are significantly younger, at face value, than the 4557±2 Ma Pb/Pb age reported for phosphates, which dates cooling through ∼550°C.
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