THE ABSORPTION OP COSMIC RAYS AND THE PRODUCTION OF KNOCK-ON SECONDARIES

Abstract

This thesis describes two investigations of cosmic- ray phenomena. The first was designed to check the exist ence of a previously observed anomaly in the absorption of cosmic rays in lead (58). The results indicate that within 1% there is no such anomaly and suggest reasons for its appearance in the earlier work. The second represents an investigation of the frequency with which knock-on secondaries are produced by penetrating particles passing through aluminum as a function of the aluminum thickness. By indirect arguments it is inferred that the physical events represent the production of knock-on electrons by mu-mesons. Therefore, the expected form of thickness variation in the knock-on process is calculated using the orbital-electron - mu-meson collision probability (86, 87) and the sea-level mu-meson momentum spectrum (88, 89). The results establish an agreement between the experimental and calculated frequency to within 5% for aluminum thicknesses from 0 to 12 gm.-cm.-2.