EXCITATION-FUNCTIONS OF PROTON-INDUCED REACTIONS ON HIGHLY ENRICHED NI-58 WITH SPECIAL RELEVANCE TO THE PRODUCTION OF CO-55 AND CO-57

Excitation functions for the independent formation of Co-55, Co-56, Co -57, Ni-16 and Ni-57 in the interactions of protons with Ni-58 were me asured radiochemically from their respective thresholds up to 35 MeV. Thin samples were prepared by electrolytic deposition of 99.87% enrich ed Ni-58 On a Au-backing. For measurements of Co-56 and Co-57 an immed iate radiochemical separation via anion-exchange chromatography was ne cessary to eliminate the contributions originating from the decay of N i-56 and Ni-57. Integral yields of the above mentioned radionuclides w ere calculated from the measured excitation functions of Ni-58(p,x) pr ocesses. Over the optimum energy range of E-p = 15 --> 7 MeV the theor etically expected Co-55-yield amounts to 14.3 MBq/mu Ah and the level of Co-57 impurity to 0.5%. The production of Co-57, On the other hand, is possible without any Co-56 impurity over the energy range of E-p = 23 --> 13 MeV; its yield amounting to 1.4 MBq/mu Ah. The competition between (p,pn) and (p,2p) processes on Ni-58 and the systematics of (p ,a) excitation functions on some even mass nickel target isotopes are briefly discussed.