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In this paper we present the prompt photofission neutron detection performance of undoped CaF2 scintillator using Threshold Activation Detection (TAD). The study is carried out in the frame of C-BORD Horizon 2020 project, during which an efficient toolbox for high volume freight non-intrusive inspection (NII) is under development. Technologies for radiation monitoring are the part of the project. Particularly, detection of various radiological threats on country borders plays an important significant role in Homeland Security applications. Detection of illegal transfer of Special Nuclear Material (SNM) - 235U, 233U and 239Pu - is particular due to the potential use for production of nuclear weapon as well as radiological dispersal device (RDD) V known also as a “dirty bomb”. This technique relies on activation of 19F nuclei in the scintillator medium by fast neutrons and registration of high-energy β particles and γ-rays from the decay of reaction products. The radiation from SNM is detected after irradiation in order to avoid detector blinding. Despite the low 19F(n,α)16N or 19F(n,p)19O reaction cross-section, the method could be a good solution for detection of shielded nuclear material. Results obtained with the CaF2 detector were compared with the previous study done for BaF2 and 3He detector. These experimental results were obtained using 252Cf source and 9 MeV Varian Linatron M9 linear accelerator (LINAC). Finally, performance of the prompt neutron detection system based on CaF2 will be validated at Rotterdam Seaport during field trails in 2018.

This research investigates the fabrication and analysis of plastic scintillators using an epoxy matrix. Plastic scintillators are widely used in radiation detection because of their low cost, ease of fabrication, resistance to moisture, and rapid decay time. The production process involved dissolving primary and secondary dopants, p-terphenyl (p-TP) and 1,4-bis [2-(phenyloxazolyl)]-benzene (POPOP), respectively, into a low-viscosity of cycloaliphatic amine as hardener B, which was then combined with Bisphenol-A diglycidyl ether as epoxy A. The ratio of primary and secondary dopants was varied in the experiment. The resulting scintillators were characterized using Fourier Transform Infrared Spectroscopy (FTIR) to analyze the functional groups that constitute the epoxy before and after curing. The morphology of the scintillator sample was evaluated using SEM and The thermal properties were evaluated with differential scanning calorimetry (DSC). The optical properties of the scintillator were studied using a UV-Vis Spectrophotometer and a Fluorescence Spectrophotometer. The performance of the scintillator in detecting gamma rays was evaluated using a module comprising a Photomultiplier Tube (PMT) and a Multichannel Analyzer (MCA) with sources of gamma Cesium 137. The results showed that epoxy-based scintillators can provide a detective response to gamma rays. This study demonstrates the potential of epoxy-based plastic scintillators for use in radiation detection. [ABSTRACT FROM AUTHOR]

Taking advantage of lanthanide chemistry and coordination dynamics, a method was elaborated to embed high amounts of organometallic complexes inside a polymeric matrix. The use of a carbonylated cross‐linker allows more than a 10‐fold increase of the solubility in monomeric solution, which can afford samples reaching up to 1 wt% incorporation of lanthanides atoms. Derivatives of these samples were used as plastic scintillators to observe total gamma‐ray absorption (Photoelectric [PE] effect) of a 241Am source. The analysis was conducted on the PE occurrence rate, which showed a discontinuity along the lanthanide row, confirming that the observed signal is indeed due to PE events. These methods also provide mechanically durable samples with stable photophysical properties comparable to a solution study of lanthanides complexes. [ABSTRACT FROM AUTHOR]

A new plastic scintillator was prepared from a renewable polymer source. It is composed of the mighty 2,5‐diphenyloxazole and 1, 4‐bis(2‐methylstyryl)benzene molecules (PPO and bis‐MSB), acting as primary and secondary fluorophores, respectively, together dissolved in a polylactic acid matrix—PLA. This polymer is indeed considered as the biomass‐based equivalent of petroleum‐derived plastics in terms of mechanical and optical properties. Subsequent to the bis‐MSB emission, the emission wavelength is centered around 424 nm and the fluorescence decay time is in the nanosecond range. The material was fully characterized, and its scintillation performances were compared to a commercial PVT‐based plastic scintillator: EJ‐200. Like polystyrene‐ or polyvinyltoluene‐based scintillators, the material displayed a good response linearity with the energy of the incident gamma‐ray. However, the observed scintillation yield was rather modest, with a reported 500 ph/MeV value when excited with a gamma‐ray‐emitting 60Co source. This preliminary test could pave the way to new and renewable polymers for unexpected applications such as nuclear physics. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48724. [ABSTRACT FROM AUTHOR]

Abstract In the field of nuclear physics, plastic scintillators are popular and efficient radiation detectors thanks to the following properties: they can be prepared in large volumes, are cheap and various configurations can be afforded to the material. However, peculiar applications might require plastic scintillator with unusual scintillation decay times, such as laser beam positioning or detectors stacking. In the case of the scintillation decay time, commercial suppliers do not propose many choices, as only the range 0.7–10 ns is usually covered, along with a longer decay time – 285 ns – material. Herein we propose a new concept and associated formulations where the scintillation decay time can be finely chosen and tuned in a range starting at 2.5 ns and finishing around 90 ns. These materials are presented, synthesized and characterized. Highlights • New plastic scintillators are presented, showing an unusual decay time. • A combination of two different primary fluorophores allows tuning the photoluminescence decay time of the material. • The plastic scintillators are fully characterized. [ABSTRACT FROM AUTHOR]

This paper introduces a novel and extremely simple—and therefore, easily implemented in a field-programmable gate array—method of neutron/gamma pulse discrimination called the histogram-difference method (HDM). Crucially, this method relies on the use of a “reference set” of \gamma -only pulses from 22Na, 137Cs, and 60Co sources and on features extracted from the pulses. The pulses from this reference set are compared to a set of an identical number of n+\gamma pulses from a 252Cf source. Not only can HDM determine the presence of neutrons in the 252Cf source, but it can also estimate the approximate percentage of neutron pulses from that source. The results reported in this paper are based on data from different radioactive sources and a standard scintillator for this type of research, namely, BC-501A. These results were confirmed using three other scintillators, one made in-house and two others that are commercially available, EJ-299–33 and EJ-200. Pulses were encoded using Q values, which are features extracted from the pulses, that is, ( , Q_{\mathrm{ tail}} ) pairs in \text{S}\mathbb {R}^{2}$ . As control, we also encoded pulses as the root-mean-square (RMS) distances from the average pulse of all known $\gamma $ -only pulses and ran HDM using these pulse representations. The results are very similar to those obtained using a $Q$ -value encoding of the pulses. [ABSTRACT FROM PUBLISHER]

Plastic scintillator loading with gadolinium-rich organometallic complexes shows a high potential for the deployment of efficient and cost-effective neutron detectors. Due to the low-energy photon and electron signature of thermal neutron capture by Gd-155 and Gd-157, alternative treatment to pulse-shape discrimination has to be proposed in order to display a count rate. This paper discloses the principle of a compensation method applied to a two-scintillator system: a detection scintillator interacts with photon and fast neutron radiation and is loaded with gadolinium organometallic compound to become a thermal neutron absorber, while a not-gadolinium loaded compensation scintillator solely interacts with the fast neutron and photon part of incident radiation. After the nonlinear smoothing of the counting signals, a hypothesis test determines whether the resulting count rate post-background response compensation falls into statistical fluctuations or provides a robust indication of neutron activity. Laboratory samples are tested under both photon and neutron irradiations, allowing the authors to investigate the performance of the overall detection system in terms of sensitivity and detection limits, especially with regards to a similar-active volume He-3 based commercial counter. The study reveals satisfactory figures of merit in terms of sensitivity and directs future investigation toward promising paths. [ABSTRACT FROM PUBLISHER]

We would like to present here with the eyes of the chemist the most recent developments of plastic scintillators (PS) for neutron detection. This review covers the period from 2000 to August 2014, and is fragmented in two main chapters. The first chapter deals with the chemical modifications for thermal neutron capture, whereas the second chapter presents the various strategies used to enhance the response to fast neutrons via pulse shape discrimination. For each chapter the theory is also explained. [ABSTRACT FROM AUTHOR]

The fast neutron nuclear reactions, such as 19 F(n, α) 16 N and 19 F(n, p) 19 O, can be used to detect highly energetic neutrons due to their energy thresholds above which these activation reactions can occur. This was recently shown (Gozani et al., 2011 [2] ) as a means to detect concealed nuclear materials via the detection of the high energy (≈3 MeV) prompt neutrons emitted during the photofission process. Fluorine-loaded scintillation detectors, such as inorganic BaF 2 and CaF 2 , and non-hydrogenous fluorocarbon (FC) liquid scintillators, such as Saint-Gobain BC-509 and Eljen Technology EJ-313, are possible candidates. The latter was selected and implemented in the above mentioned reference. In our paper, we propose a new pentafluorostyrene-based plastic scintillator (F-plastic) which can be a good alternative to the abovementioned scintillators. The fluorine content of F-plastic is equal to 3.73×10 22 atoms/cm 3 , and the F / H ratio is 1.66. The fluorescence and radioluminescence spectra of the F-plastic display an emission maximum centered approximately at 420 nm. The light output measured for gamma rays is 3100±300 photons/MeV, which is approximately 30% of the light output of the standard EJ-200 plastic scintillator and is similar to EJ-313. The response of the F-plastic to neutrons and gamma rays is presented and compared to the EJ-200 scintillator. Additionally, the n/γ pulse shape discrimination (PSD) was measured and showed improvement of the discrimination at neutron energies as high as 3 MeV. [ABSTRACT FROM AUTHOR]

Recent developments of plastic scintillators are reviewed, from 2000 to March 2014, distributed in two different chapters. First chapter deals with the chemical modifications of the polymer backbone, whereas modifications of the fluorescent probe are presented in the second chapter. All examples are provided with the scope of detection of various radiation particles. The main characteristics of these newly created scintillators and their detection properties are given. [ABSTRACT FROM AUTHOR]

Abstract: This work deals with the preparation and evaluation of plastic scintillators for neutron/gamma pulse shape discrimination (PSD). We succeeded in developing a plastic scintillator with good neutron/gamma discrimination properties in the range of what is already being commercialized. Several combinations of primary and secondary fluorophores were implemented in chemically modified polymers. These scintillators were fully characterized by fluorescence spectroscopy and under neutron irradiation. The materials proved to be stable for up to 5 years without any degradation of PSD properties. They were then classified in terms of their PSD capabilities and light yield. Our best candidate, 28.6wt% of primary fluorophore with a small amount of secondary fluorophore, shows promising PSD results and is particularly suited to industrial development, because its preparation does not involve the use of expensive or exotic compounds. Furthermore, even at the highest prepared concentration, high stability over time was observed. As a proof of concept, one sample with dimensions 109mm ∅×114mm height (≈1L) was prepared. [Copyright &y& Elsevier]

The scope of this project intends to record spatially resolved images of core shape and size of a deuterium-tritium microballoon during inertial confinement fusion (ICF) experiments at Laser Méga Joule facility (LMJ). We need to develop an x-ray imaging system which can operate in the hard radiative background generated by an ignition shot of ICF. The scintillator is a part of the imaging system and has to gather a compromise of scintillating properties (scintillating efficiency, decay time, emission wavelength) so as to both operate in the hard radiative environment and to allow the acquisition of spatially resolved images. Inorganic scintillators cannot be used because no compromise can be found regarding the expected scintillating properties. Most of them are not fast enough and emit blue light. Organic scintillators are generally fast, but present low x-ray photoelectric absorption in the 10 to 40 keV range. This does not enable the acquisition of spatially resolved images. [ABSTRACT FROM AUTHOR]

Abstract: To the aim of development of a spatially resolved x-ray imaging system intended for Inertial Confinement Fusion (ICF) experiments at the Laser Méga Joule (LMJ) facility, new plastic scintillators have been designed. The main characteristics are the following: fast decay time, red emission and good x-rays photoelectric absorption in the range 10–40keV. These scintillators are synthesized by copolymerization of different monomers with an organometallic compound. In this matrix two fluorescent compounds are embedded, allowing to shift the energy from the UV to the near IR spectrum. Several parameters were studied: fluorophores concentration, nature of the secondary fluorophore and lead concentration. An outstanding effective atomic number of 53 has been reached, for a loading of lead corresponding to 29wt%. Thus, small cylinders were prepared and their performances under x-ray beam studied and compared with those of inorganic Cerium-doped Yttrium Aluminum Garnet reference scintillator (Y3Al5O12:Ce3+). Eventually, such new scintillators or their next generation could replace expensive and brittle inorganic scintillators, inducing a strong industrial potential. [Copyright &y& Elsevier]

Radiological detection where Cherenkov residual background can be prominent requires scintillators with increased emission wavelength. Cherenkov residual background precludes the use of UV-emitting sensors such as plastic scintillators. However, the literature is scarce in red-emitting plastic scintillators and only one commercial scintillator is currently available (BC-430, from Saint-Gobain Crystals and Detectors). In addition, X-ray imaging or time-of-flight positron emission tomography (ToF-PET) applications are also demanding on this type (color) of scintillators, but such applications also require that the material displays a fast response, which is not particularly the case for BC-430. We present herein our latest developments in the preparation and characterization of fast and red plastic scintillators for this application. Here, 'fast' means nanosecond range decay time and 'red' is an emission wavelength shifted towards more than 550 nm. At first, the strategy to the preparation of such material is explained by decomposing the scintillator to fundamental elements. Each stage is then optimized in terms of decay time response, then the elemental bricks are arranged to give plastic scintillator formulations that are compatible with the abovementioned characteristics. The results are compared with the red-emissive BC-430 commercial plastic, and the ultra-fast, violet-emitting BC-422Q 1% plastic. In particular, the first-time use of trans-4-dimethylamino-4′-nitrostilbene in the scintillation field as a red wavelength shifter allowed preparing plastic scintillators with the following properties: λ em max 554 nm, photoluminescence decay time 4.2 ns, and light output ≈ 6100 ph/MeV. This means a scintillator almost as bright as BC-430 but at least three times faster. This new sensor might provide useful properties for nuclear instrumentation. [ABSTRACT FROM AUTHOR]

Abstract: This paper deals with the scintillation of fluorescent polymeric materials and their utilization in nuclear detection. Despite the importance of its applications, discrimination between fast neutrons and gamma rays in plastic scintillators remains very difficult due to the extreme sensitivity of these detectors to gamma. We have investigated the relevance of different 4-substituted 1,8-naphthalimides as fluorophores, either dispersed in a polymer matrix or copolymerized with styrene or methyl methacrylate to prepare new scintillating materials. Thus, various polymer pellets (Ø 18mm, length 10–15mm) incorporating from 0.05% to 1% of naphthalimide were prepared. The charge comparison method commonly used as discrimination technique in nuclear physics experiments was chosen. This technique lies in identifying neutrons from gamma rays by the shape of the light pulse delivered in the scintillator. Preliminary results indicate that the developed scintillators did not satisfy the discrimination criterion. [Copyright &y& Elsevier]

The choice of an appropriate viscosity of a liquid scintillator solvent can lead to the fine tuning of its decay time. We present herein the photophysical and scintillation properties of liquid scintillators containing pyrene and 9,10-diphenylanthracene as the primary and secondary fluorophores, respectively, being dissolved either in toluene, diisopropylnaphthalene or mixtures of these two solvents. By modifying the dynamic viscosity, the photoluminescence decay time can be easily chosen in the range 40–120 ns. For all liquid scintillators the light yields were satisfying, and the scintillation decays were slightly different, ranging from 36 up to 125 ns. • Liquid scintillators with unprecedent decay times are prepared. • Viscosity of the solvent mixture allows tuning the scintillation decay time. • Pyrene is used as the primary fluorophore. [ABSTRACT FROM AUTHOR]

An R&D program has been conducted to provide a formulation of a new green-emitting plastic scintillator, from the idea to commercialization. At first, various polystyrene formulations including different fluorophores were prepared and benchmarked. Several parameters were taken into account, with a main focus on the light output, the emission wavelength and the photoluminescence decay time. Once the best formulation was found at the laboratory scale with 70 cm3 samples, the scale up was performed, first with a 1 L material (still at the R&D laboratory), then 12 L scintillators produced at the factory. The methodology and a benchmark of the material against EJ-260 and BC-428 plastic scintillators are presented. This new green-emitting scintillator with catalog reference SP33 displays competitive properties for radiation detection. Its emission is centered on 500 nm, with a photoluminescence decay time of 4.8 ns and a light output around 8500 ph/MeV. • A new green-emitting plastic scintillator has been developed. • R&D was conducted on 70 cm3 samples and the final product prepared on 12 L size. • The scintillator is commercially available from Nuvia CZ with trade name SP33. [ABSTRACT FROM AUTHOR]

In the last decade, significant progress has been made in the development of plastic scintillators (PS) with effective neutron/gamma pulse shape discrimination (PSD). In this study, we investigate a plastic scintillator with remarkable neutron/gamma PSD properties for radon detection and alpha/beta PSD. The PS has outstanding alpha-/beta- PSD, energy resolution, and aging stability. It exhibits radon absorption properties with a diffusion length of 0.224(23) mm and a partition coefficient of 10.6(11) at 20(1) ° C. We show how the absorption of radon can enhance studies on the alpha/beta PSD and energy resolution of plastic scintillators. Additionally, we introduce an improved peak shape model for the approximation of the PS's alpha-particle spectrum of 222Rn and its short-lived decay products. • A plastic scintillator with neutron/gamma PSD capabilities was developed and tested. • Excellent alpha-/beta- PSD and long term stability were observed. • The diffusion length and partition coefficient of Rn-222 in the scintillator were determined. • Appropriate functions for fitting the alpha spectra are proposed and validated. [ABSTRACT FROM AUTHOR]

Review: [recent developments of plastic scintillators from 2000 to March 2014; 119 refs. [ABSTRACT FROM AUTHOR]

The aim of our study is to develop a material and associated detector that can provide a quantitative response when exposed to any kind of radionuclide decaying by the emission of alpha, beta, fast neutrons (thermalized by their environment or not) and/or gamma rays, accompanied with the categorization of such incoming radiation. To achieve this, only a single sensor is being used, composed of a three-layered, fully organic phoswich (a morphological stacking of different plastic scintillators) showing various thicknesses and decay times. The detection and sorting of fast, thermal neutrons and gamma-rays are obtained through a thick 6Li-doped scintillator. Beta and alpha detection and counting are performed respectively with thin and ultrathin films manufactured with dedicated thickness and decay times, optimized thanks to simulation studies. A Pulse Shape Discrimination method based on the charge comparison method is used to separate alpha, beta, neutrons and gamma rays contributions. We present the preparation and characterization of various configurations: quintuple discrimination, beta detection and alpha spectrometry (performed on a cocktail of alpha emitters). These experimental results are discussed and expended in the frame of complex multi-source scenarios. This all-purpose concept is trademarked as Omniscinti™. [ABSTRACT FROM AUTHOR]

Since Helium-3 shortage announcement, organic scintillators play a major role in neutron detection. Our laboratory decided to focus on plastic scintillators and their ability to discriminate fast neutrons from gamma rays. In this work, we highlight the influence of the secondary fluorophore in lab-made plastic scintillators. The secondary fluorophore is generally added in the scintillating mixture to shift the emission wavelength towards the transparency domain of the material to improve its attenuation length. Thus, it is considered as a harmless molecule and is barely seen as a key criterion that could enhance the performances of the organic scintillator. In our work, we demonstrate that this molecule, even added at a small concentration (typically in the range 0.02–0.2 wt%), directly impacts the neutron/gamma discrimination ability of plastics. Not only the secondary fluorophore plays a role in self-absorption of the scintillating material, but also the couple it creates with the primary fluorophore has to be carefully chosen, as some specific triplet energy transfers between the two fluorophores can influence the neutron/gamma discrimination abilities of the plastic scintillator. Aside from classical photophysical inconveniences such as self-absorption or diffusion, the possibility that the whole, bulk material was heterogeneous in a photochemical point of view was also checked. Thus, various samples were cut from bulk monoliths and their pulse shape discrimination compared with the parent scintillator in terms of Figure of Merit and light output. • Fast neutrons/gamma discrimination efficiency is usually reduced when the volume of a plastic scintillator is increased. • This effect is studied, first in a morphologically way, then chemically and photophysically. • The secondaray fluorophore has an essential role in the discrimination process. [ABSTRACT FROM AUTHOR]

Neutron detection forms a critical branch of nuclear-related issues, currently driven by the search for competitive alternative technologies to neutron counters based on the helium-3 isotope. The deployment of plastic scintillators shows a high potential for efficient detectors, safer and more reliable than liquids, more easily scalable and cost-effective than inorganic. In the meantime, natural gadolinium, through its 155 and mostly 157 isotopes, presents an exceptionally high interaction probability with thermal neutrons. This paper introduces a dual system including a metal gadolinium core inserted at the center of a high-scale plastic scintillator sphere. Incident fast neutrons are thermalized by the scintillator shell and then may be captured with a significant probability by gadolinium 155 and 157 nuclei in the core. The deposition of a sufficient fraction of the capture high-energy prompt gamma signature inside the scintillator shell will then allow discrimination from background radiations by energy threshold, and therefore neutron detection. The scaling of the system with the Monte Carlo MCNPX2.7 code was carried out according to a tradeoff between the moderation of incident fast neutrons and the probability of slow neutron capture by a moderate-cost metal gadolinium core. Based on the parameters extracted from simulation, a first laboratory prototype for the assessment of the detection method principle has been synthetized. The robustness and sensitivity of the neutron detection principle are then assessed by counting measurement experiments. Experimental results confirm the potential for a stable, highly sensitive, transportable and cost-efficient neutron detector and orientate future investigation toward promising axes. [ABSTRACT FROM AUTHOR]

Gadolinium-covered modified plastic scintillators show a high potential for the deployment of cost-effective neutron detectors. Taking advantage of the low-energy photon and electron signature of thermal neutron captures in gadolinium-155 and gadolinium-157 however requires a background correction. In order to display a trustable rate, dual compensation schemes appear as an alternative to Pulse Shape Discrimination. This paper presents the application of such a compensation scheme to a two-bismuth loaded plastic scintillator system. A detection scintillator interacts with incident photon and fast neutron radiations and is covered with a gadolinium converter to become thermal neutron-sensitive as well. In the meantime, an identical compensation scintillator, covered with terbium, solely interacts with the photon and fast neutron part of incident radiations. After the acquisition and the treatment of the counting signals from both sensors, a hypothesis test determines whether the resulting count rate after subtraction falls into statistical fluctuations or provides a robust image of neutron activity. A laboratory prototype is tested under both photon and neutron radiations, allowing us to investigate the performance of the overall compensation system. The study reveals satisfactory results in terms of robustness to a cesium-137 background and in terms of sensitivity in presence of a californium-252 source. [ABSTRACT FROM AUTHOR]

The development of plastic scintillators loaded with low-cost phosphorescent sensitizer is currently an important topic toward enhancing the scintillation light yield for radiation detection applications. In this work, we report plastic scintillators loaded with deep-blue-emitting phosphorescent sensitizer CuI(PPh 3) 2 (t -BuPy), where PPh 3 and t -BuPy stand for triphenylphosphine and 4- tert -butylpyridine, respectively. CuI(PPh 3) 2 (t -BuPy)-loaded poly(vinyltoluene)-based plastic scintillators with high optical transmittance of over 80% were synthesized via bulk polymerization method. The optical absorption, photoluminescence spectra, decay kinetics, and scintillation performance under X-ray, γ-ray, and α-particle excitation were comprehensively investigated. The scintillation yield was reduced with the increase of CuI(PPh 3) 2 (t -BuPy) loading concentration. The physical mechanism and the role of the copper iodide complex in scintillation yield reduction are proposed. [Display omitted] • Poly(vinyltoluene)-based plastic scintillators loaded with phosphorescent sensitizer CuI(PPh 3) 2 (t -BuPy) were synthesized. • The scintillation yield of PVT scintillators is reduced with the increase of CuI(PPh 3) 2 (t -BuPy) loading concentration. • The scintillation yield reduction is associated with the nonradiative dissipation of energy from CuI(PPh 3) 2 (t -BuPy). • Plastic scintillator containing only CuI(PPh 3) 2 (t -BuPy) showed α/γ PSD performance. [ABSTRACT FROM AUTHOR]

The development of highly efficient plastic scintillators for neutron/gamma pulse shape discrimination is a matter of current interest. This is generally achieved using two fluorophores, with one of them being added to the polymer formulation at a concentration higher than typically 15 weight percent (wt%). Here, we report our results concerning the development of highly performant poly(vinyltoluene)-based (PVT) plastic scintillators for efficient fast neutron/gamma pulse shape discrimination, using 1-phenyl-3-(mesityl)-2-pyrazoline (1) as the only guest fluorophore. On our route during this study, the synthesis of the compound 1 has been revisited. Analysis and evaluation of the radioluminescence properties of these novel PVT-based plastic scintillators containing compound 1 are also described. In particular their light output and neutron/gamma discrimination ability were characterized. The sample doped with 15 wt% of compound 1 has a light output of 0.65 relative to EJ-200 and a neutron/gamma discrimination figure of merit of 0.84 in the range 450–500 keVee. • Efficient and inexpensive synthesis of 1-phenyl-3-(mesityl)-2-pyrazoline (PMP). • PMP as primary fluorophore of plastic scintillators for fast neutron/gamma PSD. • Polymer Characterization of highly doped PVT matrix with PMP. [ABSTRACT FROM AUTHOR]

Plastic scintillators are efficient and low-cost detectors suitable for radiation detection. Obviously and as for all detectors, plastic scintillators display both advantages and drawbacks. Among disadvantages, it is known that their use is prohibited at elevated temperatures (e.g. 100 °C) due to their organic, polymeric nature. Commercial providers recommend therefore using plastic scintillators at temperatures below 60 °C to mitigate this degradation. We wish to present herein the preparation and the characterization of plastic scintillators based from cross-linked polystyrene derivatives, which allow them stability at high temperatures (i.e. tested up to 110 °C) while maintaining their scintillation properties. Their preparation, physical characterization, and relative scintillation yield estimated by radioluminescence is reported, so as to determine the influence of the cross-linking on these properties. In addition, the materials are benchmarked with two commercial plastic scintillators from Eljen technology: all-purpose EJ-200 and cross-linked EJ-244. Image 1 • Cross-linked plastic scintillators with various compositions are presented. • Their hardness (shore-D value) is retained up to 110 °C. • Scintillation properties at 110 °C are better than two commercial products. [ABSTRACT FROM AUTHOR]

We report herein the application of a new series of plastic scintillators loaded with lithium tetraborate nanoparticles (Li 2 B 4 O 7) designed for the simultaneous detection of fast neutrons, thermal neutrons and gamma-rays. First, MCNP simulations are performed to highlight the potential benefit of Li 2 B 4 O 7 loading. Then, a nanoparticle-loaded scintillator is prepared and evaluated towards the detection of a partially thermalized neutron/gamma 252-californium source. Several scenarios of radiation/matter interactions are evaluated against the observed results. A detection chamber composed of boron-containing chipboard wood has been specifically designed and a subtraction method was set up to afford the best discrimination pattern. For the first time, a triple discrimination is presented with a nanoparticles-loaded plastic scintillator, where both 6Li(n, α) and 10B(n, α) signatures are observed. A Figure of Merit of 1.40 was calculated between fast neutrons and gamma rays around 480 keVee. The Figure of Merit between fast + thermal neutrons and gamma rays is slightly worse as it is 1.16 at 380 keVee. [ABSTRACT FROM AUTHOR]