Compact lightweight imager of both gamma rays and neutrons based on a pixelated stilbene scintillator coupled to a silicon photomultiplier array

Abstract

Dual particle imaging, in which both neutrons and gamma-rays in the environment can be individually characterized, is particularly attractive for monitoring mixed radiation emitters such as special nuclear materials (SNM). Effective SNM localization and detection benefits from high instrument sensitivity so that real-time imaging or imaging with a limited number of acquired events is enabled. For portable applications, one also desires a dual particle imager (DPI) that is readily deployable. We have developed a hand-held type DPI equipped with a pixelated stilbene-silicon photomultiplier (SiPM) array module and low sampling-rate analog-to-digital converters (ADCs) processed via a multiplexed readout. The stilbene-SiPM array (12 × 12 pixels) is capable of effectively performing pulse shape discrimination (PSD) between gamma-ray and neutron events and neutron/gamma-ray source localization on the imaging plane, as demonstrated with 252Cf neutron/gamma and 137Cs gamma-ray sources. The low sampling rate ADCs connected to the stilbene-SiPM array module result in a compact instrument with high sensitivity that provides a gamma-ray image of a 137Cs source, producing 6.4 μR/h at 1 m, in less than 69 s. A neutron image for a 3.5 × 105 n/s 252Cf source can also be obtained in less than 6 min at 1 m from the center of the system. The instrument images successfully with field of view of 50° and provides angular resolution of 6.8°.

Improvement of phoswich detector‐based β+/γ‐ray discrimination algorithm with deep learning

“…The PSD technique is an algorithm that could distinguish the types of radiation by analyzing the slightly different signal pulse shapes generated upon detection. The PSD algorithms have succeeded in efficiently and accurately discriminating γ‐rays, neutrons, and alpha particles in many studies 17–22 . However, positrons and γ‐rays, when detected using a single scintillator, have essentially the similar pulse shapes; thus, it is difficult to distinguish radiation particles based only on pulse shape.…”

“…The PSD algorithms have succeeded in efficiently and accurately discriminating γ-rays, neutrons, and alpha particles in many studies. [17][18][19][20][21][22] However, positrons and γ-rays, when detected using a single scintillator, have essentially the similar pulse shapes; thus, it is difficult to distinguish radiation particles based only on pulse shape. The phoswich detector for positron detection generally comprises a two-layer scintillator of different decay times and a photosensor.…”

Dual-Particle Imaging Performance of a Cs2LiYCl6:Ce (CLYC)-Based Rotational Modulation Collimator (RMC) System

“…As a technique to further improve the detectability of SNM, a combination of the gamma-ray and neutron imaging system is particularly appealing. However, typical dual-particle imaging systems are based on the Compton camera concept and coded aperture, which require position-sensitive radiation detectors [1][2][3]. One of recent advances in the radiation imaging system includes the development of a rotating scatter mask Hyun Suk Kim is with the Division of Radiation Regulation, Korea Institute of Nuclear Safety (KINS), Daejeon, Korea (RSM) system, which identifies the direction of the source with a single detector [4][5][6][7][8].…”