First Measurement of the Asymmetry and the Gerasimov-Drell-Hearn Integrand from $\vec{{^3}He}(\vec{\gamma},p)d$ reaction at the Incident Photon Energy of 29 MeV

TL;DR

This paper reports the first experimental measurement of the spin asymmetry and Gerasimov-Drell-Hearn integrand in the $ ext{^3He}( ext{γ},p)d$ reaction at 29 MeV, providing data to test three-nucleon system theories.

Contribution

It presents the first measurement of the asymmetry and GDH integrand for the $ ext{^3He}( ext{γ},p)d$ process at 29 MeV, comparing results with advanced theoretical models.

Findings

Data agree with Siegert theorem-based predictions.

Results support meson-exchange current inclusion in models.

Provides benchmark data for three-nucleon system calculations.

Abstract

The first measurement of the $\vec{^3He}(\vec{\gamma},p)d$ process was performed at the High Intensity $\gamma$-ray Source (HI$\gamma$S) facility at Triangle Universities Nuclear Laboratory (TUNL) using a circularly polarized, monoenergetic $\gamma$-ray beam and a longitudinally polarized $^3$He target. The spin-dependent asymmetry and the contribution from the two-body photodisintegration to the $^3$He Gerasimov-Drell-Hearn integrand are extracted and compared with state-of-the-art three-nucleon system calculations at the incident photon energy of 29.0 MeV. The data are in general agreement with the various theoretical predictions based on the Siegert theorem or on explicit inclusion of meson-exchange currents.