Speaker
Description
Advanced organic scintillators with pulse shape discrimination (PSD) are critical for neutron detection in applications demanding portability, safety, and stability. While liquid scintillators like BC-501A have long served as the benchmark for PSD performance [1], their flammability, toxicity, and handling complexities limit deployment in field applications such as neutron spectroscopy, reactor technology and fusion diagnostics. The EJ-276D plastic scintillator addresses these drawbacks by offering PSD capabilities alongside enhanced safety and mechanical robustness [2], positioning it as a promising alternative.
In our prior work [2], we characterized EJ-276D’s PSD performance, time resolution, detection efficiency, and stability, demonstrating its viability for large-volume neutron detection systems. However, a critical gap remains: the light output (LO) of EJ-276D. LO has not been empirically quantified for large-volume EJ-276D. LO governs the non-linear relationship between deposited energy and measured signal amplitude (pulse height), primarily due to ionization quenching effects. For neutron spectroscopy, this parameter is essential. Accurate energy reconstruction via pulse height unfolding relies on precise knowledge of the detector’s light output response to recoil protons.
This work presents a direct comparative study of a 5-inch diameter by 5-inch length EJ-276D plastic scintillator and a dimensionally identical BC-501A liquid scintillator. The detectors were irradiated with quasi-monoenergetic neutrons in the 2-9 MeV energy range, produced via the ${}^{11}B(p,n){}^{11}C$ and ${}^{7}Li(p,n){}^{7}Be$ reactions using a proton beam from the K-130 cyclotron at the Variable Energy Cyclotron Center Kolkata. A VME-based data acquisition system was used to record pulse height, zero-crossover time, and time-of-flight data on an event-by-event basis. The functional dependency of the scintillation light output on recoil proton energy, $L(E_{p}) = aE_{p} - b[1-\exp(-cE_{p})]$, and its coefficients $a,b$ and $c$ were experimentally determined for both the detectors. Here L is the light output and $E_{p}$ is the ptoton energy. The detector's relative energy resolution, ΔL/L, was modeled as a function of the light output, L, as $\left(\frac{\Delta L}{L}\right)^2 = \alpha^2 + \frac{\beta^2}{L} + \frac{\gamma^2}{L^2}$ where $\alpha, \beta, \gamma$ are the coefficients.
Our results confirm that while the BC-501A liquid scintillator produces a higher overall light output, the EJ-276D plastic scintillator demonstrates a superior pulse height resolution. This enhanced resolution is a key advantage for high-precision spectroscopic measurements. Furthermore, these high-precision experimental data are crucial for benchmarking detector response. This dataset and the derived functional forms will be used to generate a neutron response function, which is required for unfolding the pulse height distribution. A detailed Geant4 simulation of our experimental setup is currently in progress to validate the light output functions and detector resolution parameters obtained in this work.
[1] K. Banerjee et al., Variation of neutron detection characteristics with dimension of BC501A neutron detector, Nucl. Instrum. Methods A 608 (2009) 440-446.
[2] Pankaj Pant et al., Characterization of EJ-276D plastic scintillator and its comparison with EJ-299-33A and BC-501A 2024, JINST 19 (2024) P10036.
| Position | Scientific Officer C |
|---|---|
| Affiliation | Variable Energy Cyclotron Center (VECC) Kolkata |
| Country | India |