Measurements of differential and angle-integrated cross sections for the ${}^{10}$B($n,\hat{I}\pm$)${}^7$Li reaction in the neutron energy range from 1.0 eV to 2.5 MeV

Abstract

Differential and angle-integrated cross sections for the ${}^{10}$B($n,\hat{I}\pm$)${}^7$Li, ${}^{10}$B($n,\hat{I}\pm$${}_0$)${}^7$Li and ${}^{10}$B($n,\hat{I}\pm$${}_1$)${}^7$Li${}^{\ast }$ 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 $\hat{I}¼$g/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 $\hat{I}\pm$ events were extracted from the E${}_n$-Amplitude two-dimensional spectrum. With 15 silicon detectors, the differential cross sections of $\hat{I}\pm$-particles were measured from 19.2° to 160.8°. Fitted with the Legendre polynomial series, the ($n,\hat{I}\pm$) cross sections were obtained through integration. The absolute cross sections were normalized using the standard cross sections of the ${}^{10}$B($n,\hat{I}\pm$)${}^7$Li reaction in the 0.3 - 0.5 MeV neutron energy region. The measurement neutron energy range for the ${}^{10}$B($n,\hat{I}\pm$)${}^7$Li reaction is 1.0 eV $\le$ En < 2.5 MeV (67 energy points), and for the ${}^{10}$B($n,\hat{I}\pm$${}_0$)${}^7$Li and ${}^{10}$B($n,\hat{I}\pm$${}_1$)${}^7$Li${}^{\ast }$ reactions is 1.0 eV $\le$ En < 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.

19 pages, 34 figures, to be published in Chinese Physics C