Experimental study of the low-lying negative-parity states in Be11 using the B12(d,He3)Be11 reaction

Abstract

Low-lying negative-parity states in $^{11}\mathrm{Be}$ having dominant $p$-wave neutron configurations were studied using the $^{12}\mathrm{B}(d,^{3}\mathrm{He})\phantom{\rule{0.16em}{0ex}}^{11}\mathrm{Be}$ proton-removal reaction in inverse kinematics. The $1/{2}_{1}^{\ensuremath{-}}$ state at 0.32 MeV, the $3/{2}_{1}^{\ensuremath{-}}$ state at 2.56 MeV, and one or both of the states including the $5/{2}_{1}^{\ensuremath{-}}$ level at 3.89 MeV and the $3/{2}_{2}^{\ensuremath{-}}$ level at 3.96 MeV were populated in the present reaction. Spectroscopic factors were determined from the differential cross sections using a distorted wave Born approximation method. The $p$-wave proton removal strengths were well described by the shell model calculations while the Nilsson model calculation underestimates the spectroscopic factors for the higher excited states. Results from both variational Monte Carlo and no-core shell-model calculations were also compared with the experimental observations.