Speaker
Description
Fast neutron detection plays an essential role in various fields, including nuclear data measurement, radiation shielding design and dose evaluation. In fast neutron measurements, gamma-rays are typically accompanied by neutrons in the radiation field, requiring effective neutron-gamma (n-g) discrimination. For this reason, organic scintillators are widely used because of their fast response and capability of n-g identification by using pulse shape discrimination (PSD). PSD-capable plastic scintillators like EJ-276 and EJ-299-33 have been developed recently to improve n-g discrimination performance. However, the pulse shapes of neutrons and gamma-rays become similar and overlap at the low-energy region, resulting in reduced PSD performance when using conventional charge integration methods with plastic scintillators [1, 2].
To overcome this limitation, we propose a new approach based on a two-layer scintillator detector. In this detector, Compton-scattered photons that deposit a small amount of energy and escape from the plastic scintillator are detected by a second scintillator with different scintillation properties. Signal shape differences from the two scintillators are utilized to discriminate gamma-ray events in the low-energy region. Consequently, this configuration is expected to enhance n-g discrimination and improve neutron detection efficiency in mixed radiation fields.
In this presentation, we present the conceptual design of the proposed two-layer scintillation detector and report on preliminary simulation results performed using Monte Carlo simulations with the Particle and Heavy Ion Transport code System (PHITS) [3] to evaluate the energy deposition characteristics of neutrons and gamma-rays in this configuration.
References
[1] A. Pagano, G. Croci, M. C. D’Ovidio et al., “Characterization of the EJ-299-33 plastic scintillator for neutron–gamma pulse shape discrimination with SiPM readout”, Nucl. Instrum. Methods Phys. Res. A 889, (2018), pp. 69–77.
[2] A. Grodzicka-Kobylka, A. Stolarz, T. Ginter et al., “Neutron–gamma discrimination of EJ-276 and EJ-276G plastic scintillators”, J. Instrum. 15(03), (2020), P03030.
[3] T. Sato, Y. Iwamoto, S. Hashimoto et al., “Features of Particle and Heavy Ion Transport code System (PHITS) version 3.02”, J. Nucl. Sci. Technol. 55(5-6), (2018), pp. 684-690.
