TOTAL REACTION CROSS-SECTION FOR THE BE-9+B-10 SYSTEM AT SUB-COULOMB ENERGIES

The energy dependence of the total reaction cross section for 9Be + 10B has been measured over the range Ec.m. = 1.04-4.94 MeV by detecting the γ-rays from all energetically possible residual nuclei using two large NaI(Tl) detectors placed in a 4π geometry. Between Ec.m. = 2.08-4.94 MeV, the 1.63 and 2.31 MeV γ-rays originating from the 14N second (3.945 → 2.313 MeV) and first (2.313 → g.s.) excited states were prominent. Analyzing the photopeak areas for these two γ-rays and using the assumption of statistical evaporation, the cross sections for the 14N + α + n channel have been obtained. At low energies the γ-ray spectra show evidence for a neutron transfer reaction to the 8.92 MeV, 5 2- and 9.19 MeV, 7 2+ states in 11B. The experimental total cross sections have been compared with optical-model calculations. At energies Ec.m. ≦ 2.5 MeV the energy dependence of the total reaction cross section is typical of a neutron transfer reaction with Q ≈ 0. © 1979.