Photodisintegration of $^4$He into p+t

TL;DR

This study measures the photodisintegration of helium-4 into a proton and a triton at energies above 0.4 GeV, providing new data that confirms the significance of three-body mechanisms in nuclear reactions.

Contribution

First measurement of $^4$He photodisintegration above 0.4 GeV, highlighting the importance of three-body mechanisms in the reaction.

Findings

Data agree with models including three-body mechanisms

Confirms the significance of three-body processes at 0.6-1.2 GeV

Supports previous findings on three-body mechanisms in $^3$He

Abstract

The two-body photodisintegration of $^4$He into a proton and a triton has been studied using the CEBAF Large-Acceptance Spectrometer (CLAS) at Jefferson Laboratory. Real photons produced with the Hall-B bremsstrahlung-tagging system in the energy range from 0.35 to 1.55 GeV were incident on a liquid $^4$He target. This is the first measurement of the photodisintegration of $^4$He above 0.4 GeV. The differential cross sections for the $\gamma$$^4$He$\to pt$ reaction have been measured as a function of photon-beam energy and proton-scattering angle, and are compared with the latest model calculations by J.-M. Laget. At 0.6-1.2 GeV, our data are in good agreement only with the calculations that include three-body mechanisms, thus confirming their importance. These results reinforce the conclusion of our previous study of the three-body breakup of $^3$He that demonstrated the great importance of three-body mechanisms in the energy region 0.5-0.8 GeV .