HeCTOr: the $^3$He Cryogenic Target of Orsay for direct nuclear reactions with radioactive beams

TL;DR

The paper presents HeCTOr, a high-density cryogenic $^3$He target designed for direct nuclear reactions with radioactive beams, demonstrating its stability and suitability for low-intensity experiments.

Contribution

Introduction of a novel cryogenic $^3$He target with high density and stability for nuclear physics experiments involving radioactive beams.

Findings

Target density of 10^20 atoms/cm^2 achieved

Stable temperature and density during experiments

Good agreement between simulations and experimental data

Abstract

Direct nuclear reactions with radioactive ion beams represent an extremely powerful tool to extend the study of fundamental nuclear properties far from stability. These measurements require pure and dense targets to cope with the low beam intensities. The $^3$He cryogenic target HeCTOr has been designed to perform direct nuclear reactions in inverse kinematics. The high density of $^3$He scattering centers, of the order of 10$^{20}$ atoms/cm$^2$, makes it particularly suited for experiments where low-intensity radioactive beams are involved. The target was employed in a first in-beam experiment, where it was coupled to state-of-the-art gamma-ray and particle detectors. It showed excellent stability in gas temperature and density over time. Relevant experimental quantities, such as total target thickness, energy resolution and gamma-ray absorption, were determined through dedicated Geant4 simulations and found to be in good agreement with experimental data.