Photodisintegration cross section of the reaction 4He(γ,n)3He at the giant dipole resonance peak

The photodisintegration cross section of He-4 into a neutron and helion was measured at incident photon energies of 27.0, 27.5, and 28.0 MeV. A high-pressure He-4-Xe gas scintillator served as target and detector while a pure Xe gas scintillator was used for background measurements. A NaI detector in combination with the standard HI gamma S scintillator paddle system was employed for absolute photon-flux determination. Our data are in good agreement with the theoretical prediction of the Trento group and the recent data of Nilsson et al. [Phys. Rev. C 75, 014007 (2007)] but deviate considerably from the high-precision data of Shima et al. [Phys. Rev. C 72, 044004 (2005)].