Measurement of Cross Sections for the ¹⁰ B( n ,α) ⁷ Li Reaction at 4.0 and 5.0 MeV Using an Asymmetrical Twin Gridded Ionization Chamber

Abstract

Cross sections of the 10 B(𝑛, 𝛼) 7 Li reaction (including the total, the "leaking" alpha, forward alpha and backward alpha parts) at 𝐸𝑛 = 4.0 and 5.0 MeV were measured using an asymmetrical twin gridded ionization chamber and two back-to-back 10 B samples. Measurements were performed at the 4.5 MV Van de Graaff accelerator of Peking University. Monoenergetic neutrons were produced through the 2 H(𝑑, 𝑛) 3 He reaction with a deuterium gas target. Absolute neutron flux was determined by a 238 U sample set inside the gridded ionization chamber and a BF3 long counter was employed as a neutron flux monitor and for normalization. The present results are compared with previous measurements and evaluations.

Measurements of neutron-induced light-charged particle emission reactions

“…Based on the 4.5 MV Van de Graaff accelerator at Peking University, measurement of cross sections of the three-body reaction 10 B(n, t2α) was performed [7,8]. A thin-backing 10 B sample was prepared, and the 10 B atom number in the sample was measured relative to the 6 Li atom number in the standard 6 LiF sample using thermalneutron-induced reactions of 10 B and 6 Li. Digital data acquisition system based on wave form digitizers and LAB-VIEW software were developed.…”

“…An associated white neutron source (WNS) exploiting the back-streaming neutrons (Back-n) was built for nuclear data measurement [27]. 6 Li(n, t) 4 He and 10 B(n, α) 7 Li reactions were selected as the first and the second (n, lcp) reactions to be measured. Measurements were performed at the Endstation 1 (ES#1) along the Back-n beam line.…”

“…Enriched double 6 LiF and double 10 B samples 50 mm in diameter were prepared. The detector system used for the measurement was the Light charged Particle Detector Array (LPDA), which mainly consisted of 15 silicon detectors (2.0 × 2.5 cm 2 , with detection angles ranging from 19.2 • to 160.8 • ) in a vacuum chamber.…”

“…The detector system used for the measurement was the Light charged Particle Detector Array (LPDA), which mainly consisted of 15 silicon detectors (2.0 × 2.5 cm 2 , with detection angles ranging from 19.2 • to 160.8 • ) in a vacuum chamber. Based on the CSNS Back-n WNS , and the LPDA system, the 6 Li(n, t) 4 He and 10 B(n, α) 7 Li reactions were measured. The beam durations for measurement of the 6 Li(n, t) 4 He and 10 B(n, α) 7 Li reactions were 196 h and 357 h, respectively.…”

“…By applying the techniques solving the problems above, we have been measuring the (n, lcp) reactions for years based on different neutron sources. 10 B(n,α) 4.0, 5.0 [5,6] 10 B(n,t2α)(n,α) 4.0, 4.5, 5.0 [7,8] 25 Mg(n,α)(n,α 0 ) 4.0, 4.5, 5.0, 5.5, 6.0 [9] 39 K/ 40 Ca(n, α) 4.5, 5.5, 6.5 / 5.0, 6.0 [10,11] 40 Ca(n,α 0 )(n,α 12 ) (n, α 345 ) 4.0, 4.5, 5.0, 5.5, 6.0, 6.5 [12] 2 Two decades' measurements based on the 4.…”