Photodisintegration cross sectionof ⁴He in the giant dipole resonance energy region

Murata M., Kawabata T., Adachi S., et al. Photodisintegration cross sectionof ⁴He in the giant dipole resonance energy region. Physical Review C 107, 21 (2023); https://doi.org/10.1103/PhysRevC.107.064317.
We have performed for the first time the simultaneous measurement of the two-body and three-body photodisintegration cross sections of ⁴He in the energy range from 21.8 to 29.8 MeV using monoenergetic pulsed photons and a 4π time projection chamber containing ⁴He gas as an active target in an event-by-event mode. The photon beam was produced via the Compton backscattering of laser photons with high-energy electrons. The ⁴He(γ,p)³H and ⁴He(γ,n)³He cross sections were found to increase monotonically with energy up to 29.8 MeV, in contrast to the result of a recent theoretical calculation based on the Lorentz integral transform method that predicted a pronounced peak at around 26–27 MeV. The energy dependence of the obtained ⁴He(γ,n)³He cross section up to 26.5 MeV is marginally consistent with a Faddeev-type calculation predicting a flat pattern of the excitation function. The cross section ratio of ⁴4He(γ,p)³H to ⁴He(γ,n)³He is found to be consistent with the expected value for charge symmetry of the strong interaction within the experimental uncertainty in the measured energy range. The present results for the total and two-body cross sections of the photodisintegration of ⁴He are compared to previous experimental data and recent theoretical calculations.