STUDY OF TOTAL DISCRETE GAMMA-RADIATION FROM ALUMINUM UNDER 14.9-MEV NEUTRON BOMBARDMENT

Combining the usual prompt gamma radiation measurement technique and t he lifetime correction method for delayed gamma radiation yield measur ements allows the study of total discrete gamma radiation from 14.9-Me V neutron-induced Al-27(n,x gamma) reactions. The following are identi fied: 21 prompt gamma lines from (n,n'gamma), (n,p gamma), (n,alpha ga mma), (n,n alpha gamma), (n,pn gamma), (n,d gamma), and (n,2n gamma) r eactions; 5 delayed gamma lines from one isomeric state produced in th e (n,alpha) reaction; and the beta- decay products of the residual nuc lei in the (n,p) and (n,alpha) reactions. Their differential productio n cross sections at 55, 90, and 140 deg are determined simultaneously. Compared with previous experimental results, one sees a clear advanta ge in separating the delayed component from the mixed gamma-ray peaks, which consist of prompt and delayed gamma radiation; completely clean prompt gamma-ray production data are obtained. The accurate (n,p) cro ss sections and a preliminary (n,alpha) cross section are determined f rom relative differential production cross sections. They are in good agreement with the known activation data obtained from previous measur ements and evaluations. The isomeric cross section for the 472.3-keV s tate of Na-24 is also given. The present result shows that the total g amma radiation measurement method is valuable not only to acquire accu rate gamma-ray production data but also to acquire accurate neutron ac tivation data with a wide half-life range.