EXCITATION-FUNCTIONS OF PROTON-INDUCED NUCLEAR-REACTIONS ON HIGHLY ENRICHED KR-78 - RELEVANCE TO THE PRODUCTION OF BR-75 AND BR-77 AT A SMALL CYCLOTRON

Excitation functions were measured for Kr-78(p,pn)Kr-77, Kr-78(p,x)Br-77 and Kr-78(p,alpha)Br-75 reactions from threshold to 20 MeV by the activation technique using 99.4% enriched Kr-78 as target gas. There is a strong discrepancy between our data and the literature values for the Kr-78(p,pn)Kr-77 and Kr-78(p,alpha)Br-75 reactions. Differential and integral yields of Kr-77, Br-77 and Br-75 were calculated from our excitation functions. The calculated integral yields of Br-75 and Br-77 are approximately in agreement with the low-current irradiation experimental yield data reported in the literature. The thick target yields of both Br-75 and Br-77 at a small cyclotron (E(p) almost-equal-to 17 MeV) are small [1.9 mCi (70 MBq)/muAh and 70 muCi (2.6 MBq)/muAh, respectively] and due to the very high cost of the target ps, the two production processes are uneconomical. At a medium-sized cyclotron with E(p) greater-than-or-equal-to 25 MeV, however, the Br-77 yield would be appreciably higher and the process could be very suitable for production of Br-77.