Elemental Compositions and Ages of Lunar Samples by Nondestructive Gamma-Ray Spectrometry

A gamma-ray spectrometry system with low background was used to determine the radioactivity of crystalline rocks, breccias, and fine material. Nuclides identified were $^{40}$K, $^{232}$Th, $^{238}$U, $^{7}$Be, $^{22}$Na, $^{26}$Al, $^{44}$Ti, $^{46}$Sc, $^{48}$V, $^{52}$Mn, $^{54}$Mn, and $^{56}$Co...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 1970-01, Vol.167 (3918), p.580-582
Main Authors: O'Kelley, G. Davis, Eldridge, James S., Schonfeld, E., Bell, P. R.
Format: Article
Language:English
Subjects:
Breccia
Calibration
Gamma ray spectrometers
Gamma rays
Libraries
Nuclear power
Nuclides
Potassium
Radioactive decay
Radionuclides
Stable Isotopes, Rare Gases, Solar Wind, and Spallation Products
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Summary:A gamma-ray spectrometry system with low background was used to determine the radioactivity of crystalline rocks, breccias, and fine material. Nuclides identified were $^{40}$K, $^{232}$Th, $^{238}$U, $^{7}$Be, $^{22}$Na, $^{26}$Al, $^{44}$Ti, $^{46}$Sc, $^{48}$V, $^{52}$Mn, $^{54}$Mn, and $^{56}$Co. Concentrations of K, Th, and U ranged between 480 and 2550, 1.01 and 3.30, and 0.26 and 0.83 parts per million, respectively. Concentrations of thorium and uranium were those of terrestrial basalts, while the potassium concentrations were near values for chondrites. Products of low-energy nuclear reactions showed pronounced concentration gradients at rock surfaces. Concentrations of K and of $^{22}$Na determined here were combined with concentrations of rare gases to estimate gas-retention ages and cosmic-ray exposure ages with ranges of 2200 to 3200 and 34 to 340 million years, respectively, for three rocks.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.167.3918.580