Measurements of differential and angle-integrated cross sections for the ¹⁰B(n, α)⁷Li reaction in the neutron energy range from 1.0 eV to 2.5 MeV *

Abstract

Abstract Differential and angle-integrated cross sections for the 10 B( n , α ) 7 Li, 10 B( n , α 0 ) 7 Li and 10 B( n , α 1 ) 7 Li * reactions have been measured at CSNS Back- n white neutron source. Two enriched (90%) 10 B samples 5.0 cm in diameter and ~85.0 μg/cm 2 in thickness each with an aluminum backing were prepared, and back-to-back mounted at the sample holder. The charged particles were detected using the silicon-detector array of the Light-charged Particle Detector Array (LPDA) system. The neutron energy E n was determined by TOF (time-of-flight) method, and the valid α events were extracted from the E n -Amplitude two-dimensional spectrum. With 15 silicon detectors, the differential cross sections of α -particles were measured from 19.2° to 160.8°. Fitted with the Legendre polynomial series, the ( n , α ) cross sections were obtained through integration. The absolute cross sections were normalized using the standard cross sections of the 10 B( n , α ) 7 Li reaction in the 0.3 – 0.5 MeV neutron energy region. The measurement neutron energy range for the 10 B( n , α ) 7 Li reaction is 1.0 eV≤ E n < 2.5 MeV (67 energy points), and that for the 10 B( n , α 0 ) 7 Li and 10 B( n , α 1 ) 7 Li * reactions is 1.0 eV ≤ E n < 1.0 MeV (59 energy points). The present results have been analyzed by the resonance reaction mechanism and the level structure of the 11 B compound system, and compared with existing measurements and evaluations.