Fast-neutron and gamma-ray imaging with a capillary liquid xenon converter coupled to a gaseous photomultiplier

TL;DR

This paper introduces a novel liquid xenon scintillation detector coupled with a gaseous photomultiplier for fast-neutron and gamma-ray imaging, demonstrating promising spatial resolution and potential for advanced radiography applications.

Contribution

The study presents a new detector design combining a capillary-filled liquid xenon converter with a GPM, achieving effective 2D localization of gamma-rays and neutrons with good resolution.

Findings

Achieved 12+/-2 mm spatial resolution with Co-60 gamma-rays.

Achieved 10+/-2 mm spatial resolution with AmBe neutron/gamma source.

Good agreement between experimental results and GEANT4 simulations.

Abstract

Gamma-ray and fast-neutron imaging was performed with a novel liquid xenon (LXe) scintillation detector read out by a Gaseous Photomultiplier (GPM). The 100 mm diameter detector prototype comprised a capillary-filled LXe converter/scintillator, coupled to a triple-THGEM imaging-GPM, with its first electrode coated by a CsI UV-photocathode, operated in Ne/5%CH4 cryogenic temperatures. Radiation localization in 2D was derived from scintillation-induced photoelectron avalanches, measured on the GPM's segmented anode. The localization properties of Co-60 gamma-rays and a mixed fast-neutron/gamma-ray field from an AmBe neutron source were derived from irradiation of a Pb edge absorber. Spatial resolutions of 12+/-2 mm and 10+/-2 mm (FWHM) were reached with Co-60 and AmBe sources, respectively. The experimental results are in good agreement with GEANT4 simulations. The calculated ultimate expected resolutions for our application-relevant 4.4 and 15.1 MeV gamma-rays and 1-15 MeV neutrons are 2-4 mm and ~2 mm (FWHM), respectively. These results indicate the potential applicability of the new detector concept to Fast-Neutron Resonance Radiography (FNRR) and Dual-Discrete-Energy Gamma Radiography (DDEGR) of large objects.