Excitation functons of 75As(α,n)78Br and 75As(α,2n)sup(77m),sup(g)Br reactions from threshold to 28 MeV

Excitation functions were measured by the stacked-foil technique for the reactions 75As(α,n)78Br and 75As(α,2n)sup(77m,g)Br up to Esub(α)=28 MeV. Thin samples used for measurements were prepared by an electrolytic deposition of arsenic on Cu-backing. A fast removal of radiobromine from the Cu-matrix activity was found essential for the study of the short-lived products 78Br (Tsub(1/2)=6.5 min) and 77Br (Tsub(1/2)=4.3 min). The present data appear to agree with the systematics of cross sections in this mass region. The cross-section ratio for the isomeric pair sup(77m,g)Br showed an initial increase with the α-particle energy, presumably due to the relatively high spin of the metastable state. Beyond 17 MeV, however, the ratio was found to be constant. Thick target yields were calculated for the formation of 78Br, sup(77m)Br and 77Br. In 77Br production runs, 78Br and sup(77m)Br are present in high yields (proportional500 mCi each at EOB). The possibility of production of the β+ emitter 78Br is discussed. (orig.)