10B Target Research Articles

Measurement of the 10B(n, α) reaction at En = 14.4 MeV leading to stable and unstable levels of 7Li

Spectra of alpha particles produced by neutron bombardment of an enriched 10B target have been measured. The angular distribution for two distinct alpha groups in the spectra belonging to the (n, α 0, 1) and (n, α 2) transitions are presented. The cross sections obtained are 8.2 ± 2.5 mb and 9.5 ± 2.8 mb, respectively. The latter has been measured in the angular range θ c.m. = 0°–90°. The angular distributions have been analysed in the framework of the direct reaction theory.

Evidence for the presence of alpha clusters in the boron isotopes

Thin aluminium-backed targets of 10B and 11B were bombarded with alpha particles of about 25 MeV. The alpha-particle momentum spectra taken at a lab angle of 46.4° were transformed to barycentric energy spectra after subtraction of background from the aluminum. A suggestion of four-body break-up of 10B is thus obtained, but no such simple conclusion can be drawn from the 11B spectum. The types of fragments emitted were examined and found to consist of 6Li, 4He and 2H from the 10B target and principally of 7Li and 4He from the 11B target. Some evidence for the interesting two-body reaction 11B(α, 7Li) 8Be appears.

The 10B( 3He, n) 12N reaction

Time-of-flight neutron spectra from the bombardment of 10B targets by 2.6, 3.0, 4.0 and 5.8 MeV 3He particles show neutron groups corresponding to the ground state of 12N and to excited states at E x = 0.959±0.020 ( Λ < 50 keV), 1.24±0.03 ( Λ = 140±40 keV), 2.4±0.13.14±0.08 ( Λ = 280±keV), and 3.57±0.08 MeV ( Λ = 270±80 keV). There is also some indication of additional low intensity neutron groups. The ground state Q-value is measured to be 1.568±0.020 MeV, corresponding to a 12N atomic mass excess of 17.358±0.020 MeV. The angulars distribution at E( 3 He) = 4 and 5.8 MeV show the influence of direct interaction. The results are discussed in terms of the known information on the T = 1 states in the A = 12 isobaric triad.