Investigation of the 9Be( 3He, n) 11C reaction in the energy range 3.5–10 MeV

Abstract

The excitation functions and angular distributions of neutrons from the 9Be( 3He, n) 11C reaction leading to the ground and first excited states of 11C have been measured in the energy range 3.49–9.96 MeV. The behaviour of the excitation cruves and the oscillatory pattern of angular distributions indicate that a direct interaction process is predominant in the 9Be( 3He, n) 11C reaction especially at the incident energies above 5 MeV. The angular distributions obtained at several bombarding energies have been compared with the results of DWBA calculations based on a two-nucleon stripping process, and good agreement is obtained for the data taken at 9.93 MeV. The agreement is not satisfactory at lower incident energy region, where the reaction process seems to be more complex. The neutron group leading to the first excited state of 11C shows a L = 2 pattern in higher energy region in contrast with the L = 0 pattern of the photon group observed in the mirror reaction 9Be( 3He, p) 11B. This is consistent with a selection rule for the di-proton stripping reaction and indicates that the two-nucleon stripping process is predominant in the 9Be 3He reaction.