Imaging neutrons with a position-sensitive monolithic CLYC detector

Abstract

In this work, we have developed and characterized a position-sensitive CLYC detector that acts as the neutron imaging layer and $\gamma$-ray Compton scatterer of the novel dual \g-ray and neutron imaging system GN-Vision, which aims at simultaneously obtaining information about the spatial origin of \g-ray and neutron sources. We first investigated the performance of large 50$\times$50~mm$^{2}$ monolithic CLYC crystals coupled to a pixelated SiPM in terms of energy resolution and neutron-gamma discrimination. The response of two different 95\% $^{6}$Li-enriched CLYC detectors coupled to an array of 8$\times$8 SiPMs was studied in comparison to the results of a conventional photo-multiplier tube. Energy resolution ranging from 6-8\% for the $^{137}$Cs peak and a figure of merit of 3-4 for the neutron-gamma discrimination have been obtained. The spatial response of the CLYC-SiPM detector to $\gamma$-rays and neutrons has also been characterized using charge modulation-based multiplexing techniques based on a diode-coupled charge division circuit. Average resolutions close to 5~mm FWHM with good linearity are obtained in the transverse crystal plane. Last, this work presents the first proof-of-concept experiments of the neutron imaging capability using a neutron pinhole collimator attached to the developed position sensitive CLYC detector.