Structure of 4Li and 4He observed in the 1H( alpha,3He p)n reaction.

Abstract

Kinematically complete measurements of the $^{1}\mathrm{H}$(\ensuremath{\alpha}${,}^{3}$He p)n reaction at ${\mathit{E}}_{\mathrm{\ensuremath{\alpha}}}$=170 MeV were made at several $^{3}\mathrm{He}$ and proton angles. Assuming an incoherent sum of different multipole contributions in different reaction channels, it was possible to describe all measured spectra consistently, taking into account sequential decay of states in $^{4}\mathrm{He}$ and $^{4}\mathrm{Li}$ and the p-n final state interaction. The parameters used to describe the p-n final state interaction and excited states in $^{4}\mathrm{He}$ are consistent with previous measurements. Resonance energies and widths for the ground state and the first excited state of $^{4}\mathrm{Li}$ were extracted which are considerably lower than assumed so far. The measured cross sections are in agreement with distorted-wave Born approximation calculations using folding form factors.