Performance Characterization of a Plastic-Scintillator Sensor for Fast-Neutron, Thermal-Neutron, and Gamma-Ray Discrimination
Pith reviewed 2026-05-16 21:21 UTC · model grok-4.3
The pith
A compact EJ200+EJ426 plastic scintillator assembly separates thermal neutron captures from gamma rays with a figure of merit greater than 5.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
The EJ200+EJ426 assembly provides a well separated discrimination between thermal-neutron capture events and gamma-dominated events over the measured range, with a figure of merit greater than 5. In contrast, the EJ276+EJ426 assembly produced three identifiable signal populations associated with gamma rays, fast neutrons, and thermal neutrons.
What carries the argument
Pulse shape discrimination on the combined light output from an EJ200 or EJ276 plastic scintillator optically coupled to an EJ426 thermal-neutron screen and read by a single photomultiplier tube.
If this is right
- The EJ200+EJ426 assembly enables compact detection of thermal neutrons against gamma background for radiation monitoring.
- The EJ276+EJ426 assembly identifies three separate populations, allowing simultaneous fast-neutron, thermal-neutron, and gamma measurements.
- Both assemblies offer a single-PMT readout architecture suitable for background suppression in nuclear experiments.
- Performance remains usable across the tested range of moderator thicknesses with an AmBe source.
Where Pith is reading between the lines
- The single-tube design could reduce the size and cost of portable mixed-field monitors compared with multi-detector systems.
- Extending the same coupling approach to other plastic scintillators might improve discrimination at higher count rates.
- Field tests at varying dose rates would directly confirm whether the lab-observed separation holds under realistic conditions.
Load-bearing premise
The pulse-shape separation seen with controlled lab sources will remain reliable and non-overlapping in real mixed radiation fields that contain varying rates, energies, and backgrounds.
What would settle it
An experiment in a reactor or mixed-field environment that shows overlapping pulse-shape distributions or a figure of merit below 5 for the EJ200+EJ426 assembly.
read the original abstract
Discrimination of fast neutrons, thermal neutrons, and $\gamma$ rays in mixed radiation fields is important for radiation monitoring, reactor-related measurements, and background suppression in nuclear experiments. In this work, we investigate a compact plastic-scintillator sensor composed of EJ276 or EJ200 optically coupled to an EJ426 thermal neutron screen and read out by a single photomultiplier tube (PMT). The $\gamma$ equivalent energy response of the detector assemblies was calibrated using $^{137}$Cs, $^{22}$Na, and $^{60}$Co sources through Compton edge analysis, and pulse shape discrimination was evaluated with an AmBe neutron source under different moderator thicknesses. The EJ200+EJ426 assembly provides a well separated discrimination between thermal-neutron capture events and $\gamma$ dominated events over the measured range, with a figure of merit greater than 5. In contrast, the EJ276+EJ426 assembly produced three identifiable signal populations associated with $\gamma$ rays, fast neutrons, and thermal neutrons. These results show that the proposed sensor architecture is a promising compact approach for mixed field radiation applications
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript characterizes a compact plastic-scintillator detector (EJ276 or EJ200 optically coupled to EJ426 thermal-neutron screen, read out by a single PMT) for discriminating fast neutrons, thermal neutrons, and gamma rays. Gamma-equivalent energy calibration is performed via Compton-edge analysis with 137Cs, 22Na, and 60Co sources; pulse-shape discrimination performance is evaluated using an AmBe source under varying moderator thicknesses. The central claims are that the EJ200+EJ426 assembly achieves well-separated thermal-neutron capture events from gamma-dominated events with figure of merit >5, while the EJ276+EJ426 assembly produces three distinct populations corresponding to gamma rays, fast neutrons, and thermal neutrons.
Significance. If the reported separation holds under realistic conditions, the work supplies useful experimental data on a simple, compact architecture suitable for mixed-field applications such as reactor monitoring and background suppression. The use of multiple gamma sources for calibration and moderated AmBe runs for PSD testing provides direct empirical support for the quoted figures of merit and population separation.
major comments (2)
- [Abstract and §3 (Results)] Abstract and §3 (Results): The claim that the sensor provides reliable discrimination in mixed radiation fields is supported only by sequential single-source calibrations and discrete moderator runs with AmBe. No data are shown for simultaneous irradiation with overlapping fast-neutron, thermal-neutron, and gamma fluxes at varying rates; this extrapolation is load-bearing for the stated applications (reactor monitoring, background suppression) and remains untested.
- [§2 (Experimental Methods)] §2 (Experimental Methods): The manuscript does not report error bars on the figure of merit, the number of events per histogram, or any assessment of long-term stability or rate-dependent effects (pile-up, baseline shifts), which are required to substantiate the quoted FoM >5 and the three-population separation.
minor comments (2)
- [Abstract] Abstract: Add quantitative details on event statistics, uncertainties on the FoM, and the energy range over which separation is claimed.
- [Figures] Figure captions: Ensure all PSD histograms include axis labels with units and indicate the number of events or integration windows used.
Simulated Author's Rebuttal
We thank the referee for the constructive comments on our manuscript. We address each major comment point by point below.
read point-by-point responses
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Referee: [Abstract and §3 (Results)] The claim that the sensor provides reliable discrimination in mixed radiation fields is supported only by sequential single-source calibrations and discrete moderator runs with AmBe. No data are shown for simultaneous irradiation with overlapping fast-neutron, thermal-neutron, and gamma fluxes at varying rates; this extrapolation is load-bearing for the stated applications (reactor monitoring, background suppression) and remains untested.
Authors: We acknowledge that our experiments consist of single-source calibrations and AmBe runs with varying moderator thicknesses rather than simultaneous mixed-field irradiation at arbitrary rates. The AmBe source provides a mixed fast-neutron and gamma field, with moderators adjusting the thermal neutron component, allowing us to observe the separation under different conditions. However, we agree that this does not constitute a full test of simultaneous overlapping fluxes at varying rates. In the revised manuscript, we will add a discussion of this limitation and note that the clear population separations observed support the potential for mixed-field applications, while recommending further validation in realistic environments. This constitutes a partial revision. revision: partial
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Referee: [§2 (Experimental Methods)] The manuscript does not report error bars on the figure of merit, the number of events per histogram, or any assessment of long-term stability or rate-dependent effects (pile-up, baseline shifts), which are required to substantiate the quoted FoM >5 and the three-population separation.
Authors: We appreciate this observation. In the revised manuscript, we will include statistical error bars on the reported figures of merit, derived from the uncertainties in the Gaussian fits to the PSD distributions. We will also specify the number of events contributing to each histogram. For long-term stability and rate-dependent effects, the data were acquired at controlled low count rates to avoid pile-up, and we will add a short section describing the DAQ settings and confirming no observable baseline shifts or pile-up in the waveforms. These additions will be made without requiring new measurements. revision: yes
Circularity Check
No circularity: results are direct experimental measurements
full rationale
The paper presents calibration via Compton-edge analysis on 137Cs/22Na/60Co sources and PSD evaluation on AmBe with discrete moderators. The FoM >5 and population separation are computed directly from measured pulse-shape distributions; no model equations, fitted parameters renamed as predictions, or self-citation chains are used to derive the central claims. The reported discrimination is therefore an empirical observation, not a reduction to its own inputs.
Axiom & Free-Parameter Ledger
Reference graph
Works this paper leans on
-
[1]
A. Bernstein, N. Bowden, B.L. Goldblum, P. Huber, I. Jovanovic and J. Mattingly,Colloquium: Neutrino detectors as tools for nuclear security,Rev. Mod. Phys.92(2020) 011003
work page 2020
- [2]
-
[3]
R. Carr, J. Coleman, M. Danilov et al.,Neutrino-based tools for nuclear verification and diplomacy in north korea,Sci. Glob. Secur.27(2019) 85
work page 2019
- [4]
- [5]
- [6]
- [7]
- [8]
- [9]
- [10]
-
[11]
F. Pino, L. Stevanato, D. Cester et al.,Study of the thermal neutron detector zns(ag)/lif response using digital pulse processing,JINST10(2015) T08005
work page 2015
-
[12]
R.Stedman,Scintillatorforthermalneutronsusing 6lifandzns(ag),Rev.Sci.Instrum.31(1960)1013
work page 1960
-
[13]
Jiang et al.,Study on pulse shape discrimination power of plastic scintillators,JINST17(2022) T05002
T. Jiang et al.,Study on pulse shape discrimination power of plastic scintillators,JINST17(2022) T05002
work page 2022
-
[14]
R.A. Winyard, J.E. Lutkin and G.W. McBeth,Pulse shape discrimination in inorganic and organic scintillators. I,Nucl. Instrum. Meth.95(1971) 141. [15]NEOScollaboration,Spectral measurement of electron antineutrinos from a nuclear reactor,Phys. Rev. Lett.118(2017) 121802 [1610.00582]
work page internal anchor Pith review Pith/arXiv arXiv 1971
-
[15]
Li,Detection of antineutrinos at the North Anna Nuclear Generating Station, Ph.D
S. Li,Detection of antineutrinos at the North Anna Nuclear Generating Station, Ph.D. thesis, Virginia Tech, 2020
work page 2020
-
[16]
A. Haghighat, P. Huber, S. Li et al.,Observation of reactor antineutrinos with a rapidly-deployable surface-level detector,Phys. Rev. Applied13(2020) 034028
work page 2020
-
[17]
G. Luo et al.,Design optimization of plastic scintillators with wavelength-shifting fibers and silicon photomultiplier readouts in the top veto tracker of the juno-tao experiment,Nucl. Sci. Tech.34(2023) 99
work page 2023
-
[18]
G. Luo et al.,Performance of plastic scintillator modules for top veto tracker at taishan antineutrino observatory,Nucl. Sci. Tech.36(2025) 91
work page 2025
-
[19]
K.A.A. Gamage and G.C. Taylor,Neutron gamma fraction imaging: Detection, location and identification of neutron sources,Nucl. Instrum. Meth. A788(2015) 9
work page 2015
-
[20]
K.A.A. Gamage, A.J. Crompton and M.J. Joyce,Performance characteristics of a polyethylene collimatorwithanej-426detectorinneutronsourcelocalisation,Nucl.Instrum.Meth.A755(2014)1. – 13 –
work page 2014
discussion (0)
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