Photodisintegration Cross Section of ${}^4$He in the Giant Dipole Resonance Energy Region

We simultaneously measured the ${}^4$He($\gamma ,n$)${}^3$He and ${}^4$He($\gamma ,p$)${}^3$H reactions in the energy range around the giant dipole resonance. A quasi-monoenergetic photon beam produced via the laser Compton scattering technique was irradiated on the active-target time-projection chamber filled with helium gas, and trajectories of charged decay particles emitted from ${}^4$He were measured. Our data suggest that the ${}^4$He($\gamma ,n$)${}^3$He and ${}^4$He($\gamma ,p$)${}^3$H cross sections peak around 26 MeV. This result contradicts the previous experimental data reported by Shima et al. but is consistent with other experimental results.