Be-10 and Cl-36 depth profiles in an Apollo 15 drill core

The present study of galactic cosmic ray production profiles by means of tandem accelerator mass spectrometry has measured cosmic ray-produced Be-10 and Cl-36, whose half-attenuation lengths are respectively calculated to be 120 and 132 g/sq cm. The measured half-attenuation lengths for Be-10 are noted to be slightly longer than predicted by the Reedy-Arnold (1972) theoretical model. Secondary thermal neutron production from Cl-35 is invoked as an explanation for the flatter and deeper maximum seen in the Cl-36 profile.