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

TL;DR

This study measured the photodisintegration cross sections of helium-4 around the giant dipole resonance using a laser Compton scattering photon beam and active-target detection, revealing peaks near 26 MeV and challenging previous data.

Contribution

First simultaneous measurement of $^4$He($b4, n$) and $^4$He($b4, p$) reactions in this energy region with a novel active-target TPC and laser Compton photon source.

Findings

Cross sections peak around 26 MeV.

Results contradict previous measurements by Shima et al.

Data align with some prior experimental results.

Abstract

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.