Spallation-Fission Competition in Heaviest Elements; TritonProduction

Stacked f o i l s of Au{sup 197}, Th{sup 232}, and U{sup 238} were bombarded, i n a series of experiments, with 48-Mev helium ions, 24-Mev deuterons, and 32-Mev protons. Tritium from each f o i l was collected and then measured by a gas-counting technique. The qualitative r e s u l t s indicate t h a t high-energy t r i t o n s are emitted i n r e l a t i v e l y large abundance from a l l targets and with each of the bombarding p a r t i c l e s . Cross sections f o r t r i t o n production from fissionable U 238 and Th{sup 232} and from non-f i s s ionable Au{sup 197} are comparable. The integrated (ci,t) cross sections thus determined for and 9lk-1' are nearly the same a s the integrated cross sections f o r the '(,pZn)' reactions as determined by measuring the yield of t h e product heavy isotopes i n radiochemical experiments. A l l of the f a c t s axe consistent with a picture of emission of high-energy t rmore » i t o n s (whether due t o a stripping, pick-up, or other mechanism) i n which fissionable intermediate nuclei are formed mainly a t l e v e l s of excitation be-low t h e i r f i s s i o n thresholds.« less