Measurement of the high energy $\gamma$-rays from heavy ion reactions using \v{C}erenkov detector

TL;DR

This paper develops and simulates Cherenkov detectors using water and lead glass to measure high-energy gamma rays from heavy ion collisions, enabling better understanding of nuclear short-range correlations.

Contribution

The study designs and optimizes Cherenkov detectors with detailed simulations for high-energy gamma-ray measurement in nuclear reactions, including direction reconstruction techniques.

Findings

Achieved energy resolution of 0.022+0.51/Eγ^{1/2} for water

Achieved energy resolution of 0.002+0.45/Eγ^{1/2} for lead glass

Optimized detector geometries for 160 MeV gamma-ray detection

Abstract

The energetic bremsstrahlung photons up to 100 MeV produced in heavy ion collisions can be used as a sensitive probe to the short range correlation in atomic nuclei. The energy of the $\gamma$-rays can be measured by collecting the \v{C}erenkov light in medium induced by the fast electrons generated in Compton scattering or electromagnetic shower of the incident $\gamma$ ray. Two types of detectors, based on pure water and lead glass as the sensitive material respectively, are designed for the above purpose. The $\gamma$ response and optical photon propagation in detectors have been simulated based on the electromagnetic and optical processes in Geant4. The inherent energy resolution of $0.022+0.51/E_{\gamma}^{1/2}$ for water and $0.002+0.45/E_{\gamma}^{1/2}$ for lead glass are obtained. The geometry size of lead glass and water are optimized at $30\times 30 \times 30$ cm$^3$ and $60\times 60 \times 120$ cm$^3$, respectively, for detecting high energy $\gamma$-rays at 160 MeV. Hough transform method has been applied to reconstruct the direction of the incident $\gamma$-rays, giving the ability to distinguish experimentally the high-energy $\gamma$ rays produced in the reactions on the target from the random background cosmic ray muons.