The neutron array of the compact spectrometer for heavy ion experiments in Fermi energy region

TL;DR

This paper describes the development and testing of a neutron detection array integrated into a compact spectrometer for heavy ion experiments, enabling detailed neutron spectrum measurements and correlation studies.

Contribution

The paper introduces a 20-unit neutron array with optimized detection and discrimination capabilities, enhancing neutron measurement precision in heavy ion collision experiments.

Findings

Achieved an inherent time resolution of 212 ps.

Demonstrated effective neutron-gamma discrimination.

Successfully measured neutron spectra in heavy ion collisions.

Abstract

The emission of neutrons from heavy ion reactions is an important observable for studying the asymmetric nuclear equation of state and the reaction dynamics. A 20-unit neutron array has been developed and mounted on the compact spectrometer for heavy ion experiments (CSHINE) to measure the neutron spectra, neutron-neutron and neutron-proton correlation functions. Each unit consists of a $\rm 15\times 15\times 15~cm^3$ plastic scintillator coupled to a $ \phi=52 ~\rm mm$ photomultiplier. The Geant4 simulation with optical process is performed to investigate the time resolution and the neutron detection efficiency. The inherent time resolution of 212 ps is obtained by cosmic ray coincidence test. The n-$\gamma$ discrimination and time-of-flight performance are given by $\rm ^{252}Cf$ radioactive source test and beam test. The neutron energy spectra have been obtained in the angle range $30^\circ \le \theta_{\rm lab} \le 51^\circ$ in the beam experiment of $^{124}$Sn+$^{124}$Sn at 25 MeV/u with CSHINE.