8Be Nuclear Data Evaluation

Abstract

An R-matrix analysis of experimental nuclear data on the reactions 4He(alpha,alpha), 4He(alpha,p), 4He(alpha,d), 7Li(p,alpha), 7Li(p,p), 7Li(p,n), 7Be(n,p), 6Li(d,alpha), 6Li(d,p), 6Li(d,n) and 6Li(d,d), leading to the 8Be intermediate state, has been completed in the last two years. About 4700 data points from 69 experimental references are included. The excitation energy above the 8Be ground state is 25-26 MeV for all reactions except 4He(alpha,alpha) and 7Be(n,p). The data for the reactions 4He(alpha,alpha) and 6Li(d,d) do not fit well, but the other reactions fit with a chi^2/(point) of less than the overall value of 7.9. Most of the 19 resonances found in the R-matrix analysis correspond to resonances formerly known from experiment. Evaluated integrated 4He(alpha,p), 4He(alpha,d), 7Li(p,alpha), 7Li(p,n), 7Be(n,p), 6Li(d,alpha), 6Li(d,p) and 6Li(d,n) reaction cross-sections are presented. Evaluated cross-section and angular dependence files in ENDF format were prepared for the twelve reactions p 7Li, n 7Be, d 6Li -> alpha 4He, p 7Li, n 7Be, d 6Li. Maxwellian averaged temperature-dependent cross-sections in NDI format were prepared for the six reactions 7Li(p,alpha), 7Li(p,n), 7Be(n,p), 6Li(d,alpha), 6Li(d,p) and 6Li(d,n).