Advancements in Gd-based neutron detection: $\gamma - \gamma$ coincidence approach
Abstract
CEA LIST is working on the development of a high-sensitivity thermal neutron counter, based on the insertion of gadolinium in spherical plastic scintillators. As the radiation sensor comprises one or several volumes of scintillating polymers, it is, by nature, sensitive to both neutron and gamma radiations. This property allows the development of a versatile detector, provided that it is possible to algorithmically separate the signature of both types of radiations. The technologically building brick is, moreover, to be implemented in a transportable (<15 kg) system, handled by a first intervention task force in an exposed area.
The aim of this paper is to study, both through Monte Carlo simulation and experimentally, an algorithmic architecture of the measurement chain discriminating neutron and gamma events. The presentation is subdivided in three main sections. First, we detail a comparative study between the outputs of a numerical modeling tool, developed to simulate the total response of the sensor to varying radiation sources and the results of a series of experiments carried out in a controlled environment. Second, we describe the building and numerical pre-validation of a simulation code dedicated to the study of consolidated algorithmic architecture, namely γ–γ quasi-coincidence on two adjacent plastic scintillators. Third, we comment on an experimental study of γ–γ quasi-coincidence, Gd-based neutron detection and a comparison between the results and the estimated of the numerical study. We conclude with the presentation of first estimates of neutron sensitivity), gamma-background vulnerability, and n/γ discrimination ratio for the scaled and assessed, material and algorithmic architectures.
Keywords
nuclear instrumentation
gamma background vulnerability
γ–γ quasi-coincidence
neutron sensitivity
radiation source
n/γ discrimination
sensor
discrimination neutron-gamma
scintillating polymer
neutron
gamma-rays
algorithmic architecture
Modelling
simulation
Monte Carlo
Particle transport
high-sensitivity thermal neutron counter
transportable system
first intervention task force
gadolinium
measurement chain
spherical plastic scintillator
instrumentation
ionizing radiation
plastic scintillator
Radioactivity
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