Three-body 3He photodisintegration in the Delta region.

Abstract

Three-body $^{3}\mathrm{He}$ photodisintegration was measured in the photon energy range (${\mathit{E}}_{\ensuremath{\gamma}}$) of 145--425 MeV. The total cross section for photon absorption on the np pairs in $^{3}\mathrm{He}$, \ensuremath{\sigma}${(}^{3}$He(\ensuremath{\gamma},np)${\mathit{p}}_{\mathrm{sp}}$), where ${\mathit{p}}_{\mathrm{sp}}$ is a spectator proton, is reported here for the first time. The ${\mathit{E}}_{\ensuremath{\gamma}}$ dependence of the \ensuremath{\sigma} is found to scale to that of \ensuremath{\sigma}${(}^{2}$H(\ensuremath{\gamma},np)), and the ratio is determined to be \ensuremath{\sigma}${(}^{3}$He(\ensuremath{\gamma},np)${\mathit{p}}_{\mathrm{sp}}$)/\ensuremath{\sigma}${(}^{2}$H(\ensuremath{\gamma},np))=1.24\ifmmode\pm\else\textpm\fi{}0.,26.