The excitation function for the reaction 52Cr(n, 2n) 51Cr

Abstract

The excitation function for the (n, 2n) reaction on the main isotope of the structural material chromium 52Cr(n, 2n) 51Cr has been determined from threshold to about 20 MeV using the activation technique. Quasi-monoenergetic neutrons were produced via the T(d, n) 4He reaction, making use of the neutron energy variation with emission angle. The neutron fluences seen by the 24 symmetrically arranged samples were determined relative to the well-known angular distribution of the source neutrons and the n-p scattering cross section using a recoil proton telescope. In addition they were checked around 14 MeV against the well-evaluated Nb(n, 2n) cross section. The induced 51 Cr(T 1 2 = 27.7 days) γ-ray activities were measured by means of an intrinsic solid-state Ge-detector and a carefully calibrated NaI(T1) well-type scintillator. Our results agree at 14 MeV with the many experimental results published earlier. However, they disagree above 15 MeV with two earlier experimental excitation functions, one of which was published very recently. We have also performed theoretical calculations based on direct inelastic scattering, on preequilibrium emission and on sequential evaporation from the equilibrated compound nucleus. Results show satisfying agreement with our own experimental data and similar theoretical results obtained elsewhere.