Book Synopsis 1°Be Profiles in Lunar Surface Rock 68815 by :
Download or read book 1°Be Profiles in Lunar Surface Rock 68815 written by and published by . This book was released on 1987 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Cosmic ray produced 1°Be (t12 = 1.6 x 106 years) activities have been measured in fourteen carefully ground samples of lunar surface rock 68815. The 1°Be profiles from 0 to 4 mm are nearly flat for all three surface angles measured and show a very slight increase with depth from the surface to a depth of 1.5 cm. These depth profiles are in contrast to the SCR (solar cosmic ray) produced 26Al and 53Mn profiles measured from these same samples. There is no sign of SCR produced 1°Be in this rock. The discrepancy between the data and the Reedy-Arnold theoretical calculation (about 2 dpm 1°Be/kg at the surface) can be explained in two ways: (1) the low energy proton induced cross sections for 1°Be production from oxygen are really lower than those used in the calculations or, (2) compared to the reported fits for 26Al and 53Mn, the solar proton spectral shape is actually softer (exponential rigidity parameter Ro less than 100 MV), the omnidirectional flux above 10 MeV is higher (more than 70 protons/cm2 s), and the erosion rate is higher (greater than 1.3 mm/My). 1°Be, as a high energy product, is a very useful nuclide for helping to obtain the SCR spectral shape in the past. 23 refs., 3 figs., 1 tab.
