Sputtering of uranium

A fission track technique was employed to study the sputtering of uranium by 1H+,4He+, and 40Ar+ ions with energies up to 120 keV. The technique involves detection of fission tracks produced in mica by 235U sputtered onto collector foils which are subsequently irradiated with thermal neutrons. This method is extremely sensitive and allowed measurement of sputtering yields less that 10-4 atoms per ion. It also made possible a detailed study of the emission of chunks from the uranium targets during sputtering. Mass distributions of chunks emitted during bombardment by 40-120 keV protons and by 80 keV argon are presented. Angular distributions of sputtered material and total sputtering yields for uranium metal under bombardment by 13-120 keV protons and by 40-120 keV4He+ are also presented. Sputtering yields for 40 and 80 keV40Ar+ were measured as well. Comparisons are made between the experimental results and those predicted by the collision cascade model. (author)