Evaluations Of Neutron Data For T And He-3 With R-Matrix Method

New evaluations for n+T and n+He-3 reactions are carried out by using our R-Matrix code RAC. The best R-Matrix parameters are obtained by fitting data of all necessary reactions simultaneously. The fitting for n+T reaction includes the available experimental data (E <= 40 MeV) from EXFOR database, corresponding to those of T(n, n)T, T(n, d)2n, He-3(p, p)He-3, and He-3(p, 2p)D+He-3(p, 2pn)p, while the fitting for n+He-3 reaction uses the data of He-3(n, n)He-3, He-3(n, d)D, He-3(n, p)T, He-3(n, np)D+He-3(n, 2np)H-1, He-3(n, g)He-4, T(p, p)T, and T(p, n)He-3. Then, these best R-Matrix parameters are applied to calculate the cross sections and their corresponding covariance matrices. The present evaluations agree well with the experimental data, and are obviously better than those of ENDF/B-VII, CENDL-2.1, or JENDL-3.3, particularly the cross sections for T(n,d)2n and He-3(n, np)D+He-3(n, 2np)p reactions.