Depth profile of 41Ca in an Apollo 15 drill core and the low energy neutron flux in the Moon

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dc.contributor.authorNishiizumi, Ken_AU
dc.contributor.authorFink, Den_AU
dc.contributor.authorKlein, Jen_AU
dc.contributor.authorMiddleton, Ren_AU
dc.contributor.authorMasarik, Jen_AU
dc.contributor.authorReedy, RCen_AU
dc.contributor.authorArnold, JRen_AU
dc.date.accessioned2021-10-28T02:22:02Zen_AU
dc.date.available2021-10-28T02:22:02Zen_AU
dc.date.issued1997-05-01en_AU
dc.date.statistics2021-10-21en_AU
dc.description.abstractSystematic measurements of the concentrations of cosmogenic41Ca (half-life = 1.04 × 105 yr) in the Apollo 15 long core 15001–15006 were performed by accelerator mass spectroscopy. Earlier measurements of cosmogenic10Be,14C,26Al,36Cl, and53Mn in the same core have provided confirmation and improvement of theoretical models for predicting production profiles of nuclides by cosmic ray induced spallation in the Moon and large meteorites. Unlike these nuclides,41Ca in the lunar surface is produced mainly by thermal neutron capture reactions on40Ca. The maximum productions of41Ca, about 1 dpm/g Ca, was observed at a depth in the Moon of about 150 g/cm2. For depths below about 300 g/cm2,41Ca production falls off exponentially with an e-folding length of 175 g/cm2. Neutron production in the Moon was modeled with the Los Alamos High Energy Transport Code System, and yields of nuclei produced by low-energy thermal and epithermal neutrons were calculated with the Monte Carlo N-Particle code. The new theoretical calculations using these codes are in good agreement with our measured41Ca concentrations as well as with60Co and direct neutron fluence measurements in the Moon. © 1997 Elsevier B.V.en_AU
dc.identifier.citationNishiizumi, K., Fink, D., Klein, J., Middleton, R., Masarik, J., Reedy, R. C., & Arnold, J. R. (1997). Depth profile of 41Ca in an Apollo 15 drill core and the low-energy neutron flux in the Moon. Earth and Planetary Science Letters, 148(3–4), 545-552. doi:10.1016/S0012-821X(97)00051-4en_AU
dc.identifier.issn0012-821Xen_AU
dc.identifier.issue3-4en_AU
dc.identifier.journaltitleEarth and Planetary Science Lettersen_AU
dc.identifier.pagination545-552en_AU
dc.identifier.urihttps://doi.org/10.1016/S0012-821X(97)00051-4en_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/12161en_AU
dc.identifier.volume148en_AU
dc.language.isoenen_AU
dc.publisherElsevieren_AU
dc.subjectMoonen_AU
dc.subjectMeteoritesen_AU
dc.subjectLunar materialsen_AU
dc.subjectSpallationen_AU
dc.subjectThermal neutronsen_AU
dc.subjectEpithermal neutronsen_AU
dc.subjectMonte Carlo Methoden_AU
dc.subjectNeutron fluenceen_AU
dc.titleDepth profile of 41Ca in an Apollo 15 drill core and the low energy neutron flux in the Moonen_AU
dc.typeJournal Articleen_AU
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