Neutron/gamma pulse discrimination analysis of GS10 lithium glass and EJ-204 plastic scintillators

H Al Hamrashdi,S.D Monk,D Cheneler

doi:10.1088/1748-0221/15/01/p01031

H Al Hamrashdi, S.D Monk + Show 1 more

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https://doi.org/10.1088/1748-0221/15/01/p01031

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Abstract

Two radiation sensitive scintillators known for their dual sensitivity to neutron and gamma-ray fields are investigated for their pulse discrimination abilities; a lithium glass GS10 inorganic scintillator and a fast organic plastic scintillator EJ-204. Each of these scintillators are optically coupled with an 8 × 8-silicon photomultiplier array to act as a photodetector. Pulse height analysis, the charge comparison method and pulse gradient analysis have all been applied here on neutron and gamma-ray events generated by a Cf-252 source. The three discrimination methods were evaluated based on the figure of merit of the probability density plots generated. Within a GS10 crystal, it has been deduced that pulse height analysis and pulse gradient analysis possess greater abilities to discriminate between the two radiation fields compared to the charge comparison method with both showing a figure of merit of over one. The charge comparison method indicated a lower discrimination ability with a figure of merit around 0.3. When the EJ-204 detector was used, it was deduced that only pulse height analysis exhibits discrimination abilities with a figure of merit around 0.6, while the other two discrimination methods presented no distinction between the two radiation fields.

Highlights

Applications in which mixed neutron and gamma-ray radiation fields are involved have gained steady interest through the years, especially in the areas of non-proliferation [1,2,3], radiography and tomography [4,5,6,7,8] and medical imaging [9]
The scintillation detectors assembly arranges the scintillators in series, with the GS10 scintillator located 3 cm behind the EJ-204 scintillator
4.1 Pulse height analysis method (PHA). Both neutron and gamma-ray events result in the generation of scintillation light in GS10 and EJ204

Summary

Introduction

Applications in which mixed neutron and gamma-ray radiation fields are involved have gained steady interest through the years, especially in the areas of non-proliferation [1,2,3], radiography and tomography [4,5,6,7,8] and medical imaging [9]. Research on multi-detector systems aimed at investigating both radiation fields has exhibited a slow but steady increase through the years with the first reported multi-detector system described by Aryaeinejad and Spencer in 2004 in which side-byside lithium isotope loaded glass scintillators were used [19]. This was a handheld detection device with no imaging capabilities. The system was sensitive to background radiation with no direct means of collimation to eliminate background noise Another dual neutron and gamma-ray imaging concept involves the use of organic and sometimes inorganic scintillator arrays arranged in parallel layers. The step forward from these instruments involves compact and fast scintillation materials that are sensitive to either or both radiation fields

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