EVIDENCE FOR LOW-MOMENTUM-TRANSFER PROCESS IN K41 (α,n)Sc44m,g REACTIONS FROM RANGE MEASUREMENTS OF PRODUCTS

Abstract

Average forward ranges have been measured for the product nuclides Sc43, Sc44m, and Sc44g as produced in the reactions K41(α,xn) with alpha particles in the energy region 23 to 39 Mev. These ranges, which are determined by a thick target – thick catcher technique, indicate that the (α,n)-produced isomers are formed in part by a low-momentum-transfer process above 30 Mev, its contribution being larger for the ground-state nuclide Sc44g. From a thick target –thin catcher experiment at 40 Mev, it is found that the range distribution for Sc43 is that expected for a compound-nucleus reaction. Normalizing the Sc44m and Sc44g activity distributions to that of Sc43 for the catchers farthest from the target, we estimate the lower limits for the contribution of a direct-reaction low-momentum-transfer process to the formation of Sc44m and Sc44g at 40 Mev to be about 30% and 46% respectively.