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III-nitrides have fomented a revolution in the lighting industry and are poised to make a huge impact in the field of power electronics. In the III-nitride family, the crystal growth and use of hexagonal BN (h-BN) as an ultrawide bandgap (UWBG) semiconductor are much less developed. Bulk crystals of h-BN produced by the high-temperature/high-pressure and the metal flux solution methods possess very high crystalline and optical qualities but are impractical to serve as substrates or for device implementation as their sizes are typically in millimeters. The development of crystal growth technologies for producing thick epitaxial films (or quasi-bulk or semi-bulk crystals) in large wafer sizes with high crystalline quality is a prerequisite for utilizing h-BN as an UWBG electronic material. Compared to traditional III-nitrides, BN has another unique application as solid-state neutron detectors, which however, also require the development of quasi-bulk crystals to provide high detection efficiencies because the theoretical efficiency (ηi) relates to the detector thickness (d) by η i = 1 − e − d λ , where λ denotes the thermal neutron absorption length which is 47 μm (237 μm) for 10B-enriched (natural) h-BN. We provide an overview and recent progress toward the development of h-BN quasi-bulk crystals via hydride vapor phase epitaxy (HVPE) growth and the attainment of thermal neutron detectors based on 100 μm thick 10B-enriched h-BN with a record efficiency of 60%. The thermal neutron detection efficiency was shown to enhance at elevated temperatures. Benchmarking the crystalline and optical qualities of h-BN quasi-bulk crystals with the state-of-the-art mm-sized bulk crystal flakes and 0.5 μm thick epitaxial films identified that reducing the density of native defects such as vacancies remains the most critical task for h-BN quasi-bulk crystal growth by HVPE. [ABSTRACT FROM AUTHOR]

Scintillator‐based ZnS:Ag/6LiF neutron detectors have been under development at ISIS for more than three decades. Continuous research and development aim to improve detector capabilities, achieve better performance and meet the increasingly demanding requirements set by neutron instruments. As part of this program, a high‐efficiency 2D position‐sensitive scintillator detector with wavelength‐shifting fibres has been developed for neutron‐diffraction applications. The detector consists of a double scintillator‐fibre layer to improve detection efficiency. Each layer is made up of two orthogonal fibre planes placed between two ZnS:Ag/6LiF scintillator screens. Thin reflective foils are attached to the front and back scintillators of each layer to minimize light cross‐talk between layers. The detector has an active area of 192 × 192 mm with a square pixel size of 3 × 3 mm. As part of the development process of the double‐layer detector, a single‐layer detector was built, together with a prototype detector in which the two layers of the detector could be read out separately. Efficiency calculations and measurements of all three detectors are discussed. The novel double‐layer detector has been installed and tested on the SXD diffractometer at ISIS. The detector performance is compared with the current scintillator detectors employed on SXD by studying reference crystal samples. More than a factor of 3 improvement in efficiency is achieved with the double‐layer wavelength‐shifting‐fibre detector. Software routines for further optimizations in spatial resolution and uniformity of response have been implemented and tested for 2D detectors. The methods and results are discussed in this manuscript. [ABSTRACT FROM AUTHOR]

Neutrons are widely used in national defense, security, and medical health fields. It is critical to realize neutron detection with high efficiency. The most popular neutron detection scintillators such as lithium glass and 6LiF/ZnS:Ag screen exhibit insurmountable limitations: the former usually has relatively rather low light yield and latter is opaque. In this research, we report the successful construction of the novel full inorganic composite scintillators by low temperature co‐firing technology. The composite scintillator is derived from the ZnS:Ag and borate glass matrix, and it shows better transparency compared with the standard 6LiF/ZnS:Ag screen. It exhibits excellent scintillation properties with the X‐ray induced emission intensity of these composite scintillators reaching approximately 2.46 times of the standard Bi4Ge3O12 (BGO) crystal. The light output under thermal neutron excitation can reach 75 000 photons/neutron. In addition, it presents excellent neutron detection performance with natural abundance of 10B isotope. Our research findings can serve as a valuable reference for the advancement of robust neutron detection materials, particularly in the domain of ZnS:Ag‐based full inorganic scintillator for neutron detection. [ABSTRACT FROM AUTHOR]

A scintillator-based Timepix3 (TPX3) detector was developed to resolve the high-frequency modulation of a neutron beam in both spatial and temporal domains, as required for neutron spin-echo experiments. In this system, light from a scintillator is manipulated with an optical lens and is intensified using an image intensifier, making it detectable with the TPX3 chip. Two different scintillators, namely, 6LiF:ZnS(Ag) and 6LiI:Eu, were investigated to achieve the high resolution needed for spin-echo modulated small-angle neutron scattering (SEMSANS) and modulation of intensity with zero effort (MIEZE). The methodology for conducting event-mode analysis is described, including the optimization of clustering parameters for both scintillators. The detector with both scintillators was characterized with respect to detection efficiency, spatial resolution, count rate, uniformity, and γ-sensitivity. The 6LiF:ZnS(Ag) scintillator-based detector achieved a spatial resolution of 200 μm and a count rate capability of 1.1 × 105 cps, while the 6LiI:Eu scintillator-based detector demonstrated a spatial resolution of 250 μm and a count rate capability exceeding 2.9 × 105 cps. Furthermore, high-frequency intensity modulations in both spatial and temporal domains were successfully observed, confirming the suitability of this detector for SEMSANS and MIEZE techniques, respectively. [ABSTRACT FROM AUTHOR]

Fast and high‐linearity detection of fast neutron is vital for special nuclear material seeking, nuclear accident emergency response, nondestructive neutron imaging, and neutron cancer therapy. Neutron scintillators with fast time resolution and linear energy response are indispensable for precisely acquiring the energy and temporal evolution of fast neutron, but none of the conventional neutron scintillators, whether organic, two‐component or inorganic, have performed well in this regard. To address these challenges, it is urgent to develop novel neutron scintillators. Here, 2D hybrid perovskite single crystals (C4H12N)2PbBr4 (BA2PbBr4) successfully combined with fast response time of 2.66 ns and linear energy response to fast neutrons, γ ray, and α particle, is reported. The rapid response time and linear energy response of 2D hybrid perovskite scintillator originate from intensive states density of lead halide frameworks, which are the key fluorescence emitters under neutron irradiation. This effectively suppresses the ionization quenching effect during the fluorescence process. This work represents a milestone in fast neutron detection, demonstrating a new type of neutron scintillator based on 2D hybrid perovskite single crystals with fast and high‐linearity detection characteristics, having great potential in high precision neutron spectrum measurement and nuclear reaction kinetics monitoring. [ABSTRACT FROM AUTHOR]

To minimize the environmental burden of the disposal of spent nuclear fuel, nuclide management process is one of good candidates to separate and collect major nuclides in the spent nuclear fuel. After high heat load nuclides, high mobile nuclides, and long-lived nuclides are separated, collected, and fabricated as the waste form for the disposal. From safeguards perspective, nuclear material of the TRU/RE waste form should be verified. The amount of Plutonium can be estimated by Cm/Pu ratio using burnup code calculations and Cm-244 measurement. In this study, a fast neutron coincidence counter for Cm-244 neutron measurement of the TRU/RE waste form was designed with EJ-276 plastic scintillation detectors using PTRAC of MCNP6.2. The preliminary experimental performance evaluation using one EJ-276 plastic scintillation detector was conducted. And total and coincidence counting efficiency using a Cf-252 neutron source was calculated with respect to the number of detectors. [ABSTRACT FROM AUTHOR]

In this advanced instructional laboratory, students explore complex detection systems and nondestructive assay techniques used in the field of nuclear physics. After setting up and calibrating a neutron detection system, students carry out timing and energy deposition analyses of radiation signals. Through the timing of prompt fission neutron signals, multiplicity counting is used to carry out a special nuclear material (SNM) nondestructive assay. Our experimental setup is comprised of eight trans-stilbene organic scintillation detectors in a well-counter configuration, and measurements are taken on a spontaneous fission source as well as two (α,n) sources. By comparing each source's measured multiplicity distribution, the resulting measurements of the (α,n) sources can be distinguished from that of the spontaneous fission source. Such comparisons prevent the spoofing, i.e., intentional imitation, of a fission source by an (α,n) neutron source. This instructional laboratory is designed for nuclear engineering and physics students interested in organic scintillators, neutron sources, and nonproliferation radiation measurement techniques. [ABSTRACT FROM AUTHOR]

Fast neutron and X‐ray imaging are considered complementary nondestructive detection technologies. However, due to their opposite cross‐sections, development of a scintillator that is sensitive to both fast neutrons and X‐rays within a single‐material framework remains challenging. Herein, an organic–inorganic hybrid perovskite (C4H9NH3)2PbBr4 (BPB) is demonstrated as a scintillator that fully meets the requirements for both fast neutron and X‐ray detection. The hydrogen‐rich organic component acts as a fast neutron converter and produces detectable recoil protons. The heavy atom‐rich inorganic fraction efficiently deposits the energy of charged recoil protons and directly provides a large X‐ray cross‐section. Due to the synergy of these organic and inorganic components, the BPB scintillator exhibits high light yields (86% of the brightness of a commercial ZnS (Ag)/6LiF scintillator for fast neutrons; 22 000 photons per MeV for X‐rays) and fast response times (τdecay = 10.3 ns). More importantly, energy‐selective fast neutron and X‐ray imaging are also demonstrated, with high resolutions of ≈1 lp mm−1 for fast neutrons and 17.3 lp mm−1 for X‐rays; these are among the highest resolution levels for 2D perovskite scintillators. This study highlights the potential of 2D perovskite materials for use in combined fast neutron and X‐ray imaging applications. [ABSTRACT FROM AUTHOR]

A new compact time-of-flight neutron detector is being planned for the identification and energy measurement of neutrons produced in nucleus-nucleus interactions at energies up to 4 AGeV at the BM@N experiment, located at the Nuclotron (Joint Institute for Nuclear Research, Dubna, Russia). This detector will be used to measure neutron yields and azimuthal flows, which should be sensitive to the equation of state of dense nuclear matter, as shown in various theoretical models It is proposed to use plastic scintillators produced at JINR and IFTP and silicon photomultipliers with a sensitive area of 6 × 6 mm2 for photon registration, one for each scintillation cell. To achieve the required neutron energy resolution (of the order of several percent) in the energy range up to 4 GeV, the time resolution of scintillation detectors should be 100−150 ps. The concept of a time-of-flight neutron detector is discussed. The results of measurements of the light yield and time resolution of several scintillation detector specimens of various sizes and two types of silicon photomultipliers are presented. [ABSTRACT FROM AUTHOR]

The technological aspects of the light inorganic crystalline compounds suitable to create scintillation materials to detect charged particles and neutrons in a wide energy range have been examined. Among them, Li2CaSiO4:Eu was found to be a prospective candidate to control the valent state of the Rare Earth (RE) and to provide a high intensity of luminescence. It was demonstrated that the material has room for future improvement; however, this requires precise engineering of its composition—an experimental search of compositions or additives that will provide the maximum Eu2+/Eu3+ ratio to achieve a high scintillation light yield. The benefits of light inorganic materials are disclosed through the modeling of the linear density of nonequilibrium carriers along secondary particle tracks created in scintillators utilized for neutron detection. It is shown that oxide matrices have a larger linear density in comparison with halide crystalline compounds under alpha-particles and tritons, whereas light oxides can provide smaller numbers under protons. [ABSTRACT FROM AUTHOR]

Glass scintillators have several benefits compared to the currently used single or polycrystalline scintillators, including non‐hygroscopicity, mechanical ruggedness, ease of producing customizable shapes, and low‐cost synthesis. The combination of the inert glass matrix and the embedded highly scintillating center render them significant materials for medical imaging and therapy, non‐destructive probing, nuclear monitoring, and high‐energy physics. Recently, great progress has been made in exploring new kinds of glass scintillator materials, improving imaging resolution for radiation detection, and developing an enormous range of commercial products. However, the majority of efforts have been devoted to the variation of materials, while rationally designing this new family of scintillators toward expected properties and applications is still lacking. In this review, the focus is specifically on advances in glass scintillators, including the scintillation fundamentals, material designing rule, and current application status, as well as future challenges and future directions. [ABSTRACT FROM AUTHOR]

Scintillation material presents a variety of applications used in radiation environments such as dosimetry, spectrometry, and radiography facility. Neutron radiography is a non-destructive testing (NDT) method that uses a proper scintillator such as LiI/ZnS for neutron detection. This paper investigated the effect of neutron-induced point defects on the optical properties of this scintillator used in TRR's neutron radiography system. The combination of Monte Carlo and atomistic modeling methods was utilized in this regard. The results showed that the induced point defects lead to a more than 10 and 22% reduction in the refractive index and reflectivity of the LiI scintillator at optical wavelength respectively. Moreover, the refractive index of the ZnS scintillator decreases more than 6.4 % by Zn interstitial, Zn vacancy, and S vacancy and increases 8.9 % by S interstitial at optical wavelength. [ABSTRACT FROM AUTHOR]

Thermal neutron detection is a key subject for nuclear physics research and also in a wide variety of applications from homeland security to nuclear medicine. In this work, it is proposed a novel flexible and conformable composite thermal neutron scintillator based on a fully enriched Lithium Tetraborate preparation ( 6 Li 2 10 B 4 O 7 ) combined with a phosphorescent inorganic scintillator powder (ZnS:Ag), and is then distributed into a polydimethylsiloxane matrix. The proposed scintillator shows a good neutron detection efficiency (max. ∼ 57% with respect to the commercial EJ-420), an average light output of ∼ 9000 ph/neutron-capture, a remarkable insensitivity to γ -rays (Gamma Rejection Ratio <10 - 11 ), and an extraordinary flexibility, so as to reach extremely small curvature radii, down to 1.5 mm, with no signs of cracking or tearing. Its characteristics make it suitable to be employed in scenarios where non-standard geometries are needed, for example, to optimize the detector performance and/or maximize the detection efficiency. Finally, the response of a hybrid detector made of a plastic scintillator, wrapped with the proposed scintillator, coupled to a silicon photomultiplier array is described, and the excellent discrimination between γ -rays, fast and thermal neutrons resulting from data processing is demonstrated. [ABSTRACT FROM AUTHOR]

Additive manufacturing techniques enable a wide range of possibilities for novel radiation detectors spanning simple to highly complex geometries, multi-material composites, and metamaterials that are either impossible or cost prohibitive to produce using conventional methods. The present work identifies a set of promising formulations of photocurable scintillator resins capable of neutron-gamma pulse shape discrimination (PSD) to support the additive manufacturing of fast neutron detectors. The development of these resins utilizes a step-by-step, trial-and-error approach to identify different monomer and cross-linker combinations that meet the requirements for 3D printing followed by a 2-level factorial parameter study to optimize the radiation detection performance, including light yield, PSD, optical clarity, and hardness. The formulations resulted in hard, clear, PSD-capable plastic scintillators that were cured solid within 10 s using 405 nm light. The bestperforming scintillator produced a light yield 83% of EJ-276 and a PSD figure of merit equaling 1.28 at 450-550 keVee. [ABSTRACT FROM AUTHOR]

Neutron detection using gadolinium (Gd) and its prompt gamma-rays is vital because of the high cross-section of Gd on thermal neutrons, thereby leading to significant interest in neutron detection with Gd-converted or Gd-loaded detector. However, simultaneous detection of neutron and gamma-rays with a Gd-loaded scintillator has been given less attention. In this study, we explored the feasibility of the GdI3:Ce detector for simultaneous detection with Monte Carlo N-Particle transport extended simulation. Furthermore, we examined the physical properties of Gd for application in the radiation field mixed with neutron and gamma-rays. Similarly, we simulated the geometry of the GdI3:Ce scintillator and its spectra obtained under various conditions. The results showed that GdI3:Ce with a thickness of 1 cm is enough to absorb 90 % of photons with energy under 81 keV. A shorter source-to-detector distance and larger detector size were superior to detecting prompt gamma-rays emitted from neutron capture, not only the gamma-rays from isomeric transition (named as general gamma-ray in this paper). Ultimately, spectra taken with the Gd3:Ce scintillator under the radiation field mixed with neutrons and gamma-ray showed gamma-ray peaks from both radio-isotopes and Gd (n γ) Gd reaction, indicating the feasibility of the application of simultaneous detection. [ABSTRACT FROM AUTHOR]

The paper considers and compares methods for obtaining spectra of fast neutrons using detectors based on a diamond sensor, an organic (plastic) scintillator for separating neutrons and γ-quants, and a spectrometric set of threshold activation detectors. The neutron spectrum was unfolded using the methods of least squares, Tikhonov regularization, neural networks, and maximum entropy, implemented in the MAXED code, as well as the GRAVEL iterative algorithm. In order to form detector response matrices, mathematical simulation methods and analytical calculations were used followed by verification using experimental data. The unfolding quality criteria, according to which the best method is selected, are given. [ABSTRACT FROM AUTHOR]

We report the preparation of the ZnO-6LiF composite with a polystyrene (PS) polymer as a host using the solution mixing process. 6LiF acts as a converter material that absorbs a thermal neutron and produces alpha particles, which excites ZnO micro-particles, resulting in UV–vis photons' emission. The free-standing ZnO-6LiF/PS composite film is coupled to a photomultiplier tube (PMT). 241Am-Be (1Ci) is used as the neutron radiation source for measuring the response. We compared the response of the composite scintillator consisting of (i) natural LiF and (ii) 95% 6Li enriched LiF (6LiF). The increased pulse heights are recorded for 95% 6Li enriched, i.e., 6LiF converter. It confirms the generation of alpha particles after the absorption of a neutron in 6LiF. Furthermore, ZnO and 6LiF are considered in different weight proportions, 2:1, 1:1, and 1:2, keeping the total loading 50% (w/w) of polystyrene. The ZnO:6LiF (1:1)/PS composite showed higher scintillation pulse heights than the other two composites. Repetitive measurements are performed for the ZnO-6LiF(1:1)/PS composite, showing ±5% variation in respective responses. We also investigated the impact of different counting times and source-to-detector responses for the ZnO-6LiF(1:1)/PS composite. The response increases linearly with neutron dose, exhibiting a sensitivity of ∼203 counts/μSv. Neutron measurement counts at different source-to-detector distances have a similar trend as that of neutron dose measured by using a neutron dosimeter. Thus, this work demonstrated the potential of the ZnO-6LiF/PS composite, coupled to PMT for detecting thermal neutron radiation. [ABSTRACT FROM AUTHOR]

A detector of the proton telescope type utilized at the RFNC-VNIIEF for detection of DT neutrons and the principle of its operation are described. The main goal of the study was to simulate the spectra of recoil protons in the detector, which includes taking into account the kinematics of elastic H(n, n) scattering, proton energy losses in hydrogen-containing radiator and scintillator, and nonlinearity of the light yield of inorganic scintillators. The spectra of recoil protons for several neutron energies have been simulated and compared with data of experiments on DT neutrons. [ABSTRACT FROM AUTHOR]

The article presents results of research and development in creating new combined neutron-detecting materials based on scintillating polymer elements, as well as actinide dioxide radiators. New functional combinations of materials for detecting neutrons in a wide energy range are proposed. The obtained spectral and counting rate characteristics of the samples can be used in the selective detection of neutron flux components and the subsequent separation of signals. [ABSTRACT FROM AUTHOR]

Dedicated nuclear diagnostics have been designed, developed, and built within EUROFUSION enhancement programs in the last ten years for installation at the Joint European Torus and capable of operation in high power Deuterium–Tritium (DT) plasmas. The recent DT Experiment campaign, called DTE2, has been successfully carried out in the second half of 2021 and provides a unique opportunity to evaluate the performance of the new nuclear diagnostics and for an understanding of their behavior in the record high 14 MeV neutron yields (up to 4.7 × 1018 n/s) and total number of neutrons (up to 2 × 1019 n) achieved on a tokamak. In this work, we will focus on the 14 MeV high resolution neutron spectrometers based on artificial diamonds which, for the first time, have extensively been used to measure 14 MeV DT neutron spectra with unprecedented energy resolution (Full Width at Half Maximum of ≈1% at 14 MeV). The work will describe their long-term stability and operation over the DTE2 campaign as well as their performance as neutron spectrometers in terms of achieved energy resolution and high rate capability. This important experience will be used to outline the concept of a spectroscopic neutron camera for the SPARC tokamak. The proposed neutron camera will be the first one to feature the dual capability to measure (i) the 2.5 and 14 MeV neutron emissivity profile via the conventional neutron detectors based on liquid or plastics scintillators and (ii) the 14 MeV neutron spectral emission via the use of high-resolution diamond-based spectrometers. The new opportunities opened by the spectroscopic neutron camera to measure plasma parameters will be discussed. [ABSTRACT FROM AUTHOR]

Composite materials consisting of 6Li scintillator particles in an organic matrix can enable thermal neutron detectors with excellent rejection of gamma-ray backgrounds. The efficiency of transporting scintillation light through such a composite is critical to the detector performance. This optical raytracing study of a composite thermal neutron detector quantifies the various sources of scintillation light loss and identifies favorable photomultiplier tube (PMT) readout schemes. The composite material consisted of scintillator cubes within an organic matrix shaped as a right cylinder. The cylinder surface was surrounded by an optical reflector, and the light was detected by PMTs attached to the cylinder end faces. A reflector in direct contact with the composite caused 53% loss of scintillation light. This loss was reduced 8-fold by creating an air gap between the composite and the reflector to allow a fraction of the scintillation light to propagate by total internal reflection. Replacing a liquid mineral oil matrix with a solid acrylic matrix decreased the light transport efficiency by only ∼10% for the benefit of creating an all-solid-state device. The light propagation loss was found to scale exponentially with the distance between the scintillation event and the PMT along the cylinder main axis. This enabled a PMT readout scheme that corrects for light propagation loss on an event-by-event basis and achieved a 4.0% energy resolution that approached Poisson-limited performance. These results demonstrate that composite materials can enable practical thermal neutron detectors for a wide range of nuclear non-proliferation and safeguard applications. [ABSTRACT FROM AUTHOR]

A new neutron time-of-flight (nTOF) detector for deuterium–deuterium (DD)-fusion yield and ion-temperature measurements was designed, installed, and calibrated for the OMEGA Laser Facility. This detector provides an additional line of sight for DD neutron yield and ion-temperature measurements for yields exceeding 1 × 1010 with higher precision than existing detectors. The nTOF detector consists of a 90-mm-diam, 20-mm-thick BC-422 scintillator and a gated Photek photomultiplier tube (PMT240). The PMT collects scintillating light through the 20-mm side of the scintillator without the use of a light guide. There is no lead shielding from hard x rays in order to allow the x-ray instrument response function of the detector to be measured easily. Instead, hard x-ray signals generated in implosion experiments are gated out by the PMT. The design provides a place for glass neutral-density filters between the scintillator and the PMT to avoid PMT saturation at high yields. The nTOF detector is installed in the OMEGA Target Bay along the P8A sub-port line of sight at a distance of 5.3 m from the target chamber center. In addition to DD measurements, the same detector can be used to measure the neutron yield and ion temperature from deuterium–tritium (DT) implosion targets in the 5 × 1010 to 2 × 1012 yield range. The design details and the calibration results of this nTOF detector for both D2 and DT implosions on OMEGA will be presented. [ABSTRACT FROM AUTHOR]

To analyze the effect of scintillator detectors on the fast neutron multiplicity, this paper uses Geant4 and Matlab to simulate and study three types of scintillator detectors: BC501A, EJ-309 and Stilbene. It's found that EJ-309 has the highest detection efficiency and the smallest measurement deviation. The energy spectrum of the recoil particles is collected to analyze the reason. The results show that Stilbene has the lowest proportion of hydrogen nuclei, which causes poor measurement results. On this basis, we found that a lower carbon: hydrogen molar ratio and a greater density correspond to a better measurement efficiency, and nuclide deuterium has better measurement efficiency than hydrogen nuclide. [ABSTRACT FROM AUTHOR]

Samples of composite scintillators consisting of NE 912 lithium glass fragments located in an organic matrix have been developed and manufactured. Samples were made in sizes of ∅40 × 2 mm with 25, 30, and 35% lithium glass concentration. Epoxy and acrylic resins, as well as a silicone compound, were used as a neutral matrix. Samples were tested as part of a scintillation detector on a thermal neutron beam and with source of γ-quanta 60Co. The efficiency of thermal neutrons' registration and γ-sensitivity compared to a homogeneous glass scintillator was determined. The results obtained confirmed the possibility of reducing the sensitivity of the detector to γ-quanta by two orders of magnitude due to a slight (50%) decrease in the efficiency of neutron detection. [ABSTRACT FROM AUTHOR]

NaI(Tl) scintillators can detect thermal neutrons with surprising efficiency, even in the presence of ambient gamma radiation. This is due to a peculiarity of the 128I level scheme. Deexcitation cascades following neutron captures in 127I, a main constituent of NaI with quite large neutron capture cross section, unexpectedly often involve the 167.4 keV state of 128I with 175 ns half-life, which feeds another isomeric level at 137.9 keV having a half-life of 845 ns. The 29.5 keV transition between both levels, as well as the subsequent deexcitation sequence to ground state comprising 137.9 keV sum energy, are almost certainly absorbed in the crystal. Signals including three scintillation pulses within few microseconds, the first one caused by a prompt part of the cascade, the second and third one disclosing 30 and 138 keV energy depositions and characteristic delays, are clearly related to such neutron captures. Double-pulse sequences comprising only the primary pulse and a delayed 138 keV signal are also distinctive but more prone to load-dependent background by random pulse pileups. This article demonstrates neutron detection with a Ø2” $\times2$ ” NaI(Tl) scintillation detector by finding and analyzing such double- and triple-pulse sequences in digitized detector signals. It quantifies effect and background rates as a function of the detector load ranging up to 30 kcps. Complementary measurements with a 6Li codoped Ø2” $\times2$ ” NaI(Tl) (NaIL) scintillator allow relating the neutron detection yield by delayed-coincidence counting to the 6Li capture rate in the same crystal and thus to evaluate prospects and limits of this technique. [ABSTRACT FROM AUTHOR]

A novel non-destructive testing scanning system based on a large-size line array fast neutron detector and compact D-T neutron source has been constructed. The scanning range is up to 1000 mm, and the resolution is better than 1 mm. The fast neutron detection subsystem consists of a polypropylene zinc sulfide scintillator embedded with wavelength-shifting fibers, coupled with a light lens and a scientific CCD camera. With a new rotating tritium target, the lifetime of the compact D-T neutron source could achieve ten hours. The experimental results indicate that the scanning method based on line array fast neutron detector and D-T neutron source is feasible and enables the detection of slits on the order of 0.5 mm in width. Fast neutron tomography has been realized by this detection system too. [ABSTRACT FROM AUTHOR]

We synthesized an alcohol-based liquid scintillator (AbLS), and we implemented an auxiliary monitoring system with short calibration intervals using AbLS for particle therapy. The commercial liquid scintillator used in previous studies did not allow the user to control the chemical ratio and its composition. In our study, the chemical ratio of AbLS was freely controlled by simultaneously mixing water and alcohol. To make an equivalent substance to the human body, 2-ethoxyethanol was used. There was no significant difference between AbLS and water in areal density. As an application of AbLS, the range was measured with AbLS using an electron beam in an image analysis that combined AbLS and a digital phone camera. Given a range–energy relationship for the electron expressed as areal density, the electron beam range (cm) in water can be easily estimated. To date, no literature report for the direct comparison of a pixel image analysis and Monte Carlo (MC) simulation has been published. Furthermore, optical tomography of the inverse problem was performed with AbLS and a mobile phone camera. Analyses of optical tomography images provide deeper insight into Radon transformation. In addition, the human phantom, which is difficult to compose with semiconductor diodes, was easily implemented as an image acquisition and analysis system. [ABSTRACT FROM AUTHOR]

Measurement of the space neutron radiation environment has put forward new requirements for the miniaturization and lightweight design of neutron spectrometers. In this paper, a compact broad-spectrum neutron spectrometer was designed, in which the fast neutron detector was based on the EJ-254 scintillator-coupled with SiPMs array, and the thermal and epithermal neutron detectors were based on the NaI(Tl + Li) (NaIL) scintillator coupled with SiPMs array encapsulated in Al and Cd shells, respectively. The overall weight of the neutron spectrometer was only 2.4 kg, and its dimensions were 154 mm × 123 mm × 115 mm. The fast neutron energy spectrum was obtained based on the capture-gated method and the Maximum Likelihood Expectation Maximization (MLEM) unfolding algorithm; the counts of thermal and epithermal neutrons were obtained based on the optimized frequency-domain Pulse Shape Discrimination (PSD) method and cadmium difference method. The proposed neutron spectrometer with all applied methods was tested as a whole system with a252Cf and a241Am–Be source. The spectrum result was compared to an ISO standard source. The accuracy of fast part of 0.5–10 MeV was 5.9% in definition of Relative Root Mean Squared Error (RRMSE). The thermal and epithermal neutron counts were far higher than standard spectrum, and we proved it being effected by laboratory introduced neutron scattering through a simulation, thus the thermal and epithermal flux measurements was believed to be decent. The Figure of Merit (FoM) of the NaIL's PSD neutron gamma discrimination were 2.57 and 2.90 respectively. [ABSTRACT FROM AUTHOR]

• 1.0-inch diameter 6LiI:Ag crystals were successfully grown using Bridgman method. • The maximum neutron-gamma PSD figure of merit was obtained to be 1.3. • Energy resolution of the thermal neutron peak of 12.0% can be observed. • 6LiI:Ag is promising neutron detectors in high neutron-gamma mixed fields. This paper discusses crystal growth and characterization of 1.0-inch 6LiI:Ag scintillators for thermal and epithermal neutron detection on the lunar surface as part of the Lunar Vehicle Radiation Dosimeter project. Zone purification method was employed to purify the raw material of 6LiI, and the crystals were grown using the Bridgman method. X-ray luminescence spectrum was measured to confirm the presence of Ag+ in the crystal lattice of 6LiI. The feasibility of neutron detection under 252Cf fast neutron irradiation was investigated. A hydrogen-rich paraffin wax moderator was used to slow down fast neutrons to obtain thermal and epithermal neutrons. The charge comparison method was used to perform pulse shape discrimination. The maximum value of the Figure of Merit was obtained to be 1.3, which demonstrates the capability of using 6LiI:Ag crystal scintillators in high neutron and gamma mixed fields. The energy resolution of the thermal neutron peak varied with the thickness of scintillators, achieving 12.0 % for the 0.5 cm thick samples. The potential for further improvement of the scintillation performance of 6LiI:Ag crystal relies on reducing impurities and color centers. [ABSTRACT FROM AUTHOR]

Knowledge of the neutron light-yield response is crucial to the understanding of scintillator-based neutron detectors. In this work, neutrons from 2–6 MeV have been used to study the scintillation light-yield response of the liquid scintillators NE 213A, EJ 305, EJ 331 and EJ 321P using event-by-event waveform digitization. Energy calibration was performed using a GEANT4 model to locate the edge positions of the Compton distributions produced by gamma-ray sources. The simulated light yield for neutrons from a PuBe source was compared to measured recoil proton distributions, where neutron energy was selected by time-of-flight. This resulted in an energy-dependent Birks parameterization to characterize the non-linear response to the lower energy neutrons. The NE 213A and EJ 305 results agree very well with existing data and are reproduced nicely by the simulation. New results for EJ 331 and EJ 321P, where the simulation also reproduces the data well, are presented. [ABSTRACT FROM AUTHOR]

Two organic scintillators (EJ309 and stilbene) with their different detection chains and elaborate software were used to measure neutron spectra of AmBe and PuC sources. Method of shadow cone ensures minimization of scattered neutron influence. To separate neutrons and γ, a modern method of pulse shape discrimination was employed using fast digitizers. Calibration was performed by γ sources and three different methods for the identification of the Compton edge. Spectrometric systems also used different light output functions and unfolding methods. The same spectra were calculated using the MCNP6 code and the JENDL-5 library. The measured and calculated results were mutually compared, and also with the published results available in the literature. Generally, the results agree on the main peaks of neutron spectra but differ in their abundance. The lower limit for the ability to distinguish between neutrons and γ in spectrometry with organic scintillators was found at about 1.5 MeV. • Neutron spectra of AmBe and PuC sources were measured and calculated. • The measured/unfolded spectra and calculated ones agree in shape. • Methods of energy calibration and neutron/gamma separation are described. [ABSTRACT FROM AUTHOR]

The utilization of large-scale neutron detector arrays in future experiments is of vital importance to increase our understanding of β -delayed neutron emitters. A new device, DAEMON (Detector Array for Energy Measurements Of Neutrons), is being designed for the GRIFFIN decay station at TRIUMF-ISAC. DAEMON will improve the precision on the measurement of the neutron kinetic energy through the use of thin plastic scintillators, SiPMs arrays, and the Time-of-Flight technique, to enhance the current capabilities to study neutron rich nuclei at TRIUMF. The performance and feasibility of the DAEMON array was investigated using the Geant4 package to simulate and optimize the experimental design. To test the optical parameters and models implemented in the Geant4 simulations, a comparison with experimental data from small plastic scintillators combined with SiPM detectors was performed. The simulations reproduce the experimental data very well, including features introduced by summing 2 × 2-SiPM arrays in software. This work lays the foundation for simulations of the full DAEMON array. [ABSTRACT FROM AUTHOR]

Improved neutron inelastic scattering cross section data are needed to inform integral benchmark studies and advance applications in a wide variety of areas including nuclear energy, stockpile stewardship, nonproliferation, and space exploration. Neutron inelastic scattering also serves as a non-selective probe of low-lying nuclear structure. To help meet these needs, the Gamma Energy Neutron Energy Spectrometer for Inelastic Scattering (GENESIS) was constructed at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory. This array couples high-resolution γ -ray detectors and fast neutron detectors to achieve single and coincident n/ γ detection over a broad energy range. The current configuration of the array includes 26 organic liquid scintillators and four high-purity germanium detectors (two single-crystal and two four-crystal CLOVER detectors with two-fold segmentation). The array was constructed with minimal supporting material and designed to cover a wide range of secondary particle angles and energies with limited inter-element scattering. Data acquisition is accomplished using Mesytec MDPP-16 multi-channel high-resolution digital pulse processing modules. The array characteristics, including γ -ray and neutron energy resolution, timing resolution, and detection efficiency were measured and used to validate a Geant4 model of the array. The primary sources of neutron background and the uncertainties in the determination of incident and secondary neutron energy were assessed. GENESIS provides a new capability to address nuclear data needs and facilitates the advancement of a wide range of nuclear applications. [ABSTRACT FROM AUTHOR]

Trans -stilbene single crystal possesses the advantages of high luminescence efficiency, short response time, stable radiation/strong light resistance and remarkable neutron/gamma pulse shape discrimination (PSD) properties, rendering it arguably the leading candidate for organic scintillators. Here, by the improvement of the thermal field, solvent and sealing on our self-designed equipment, precise growth control resulted trans -stilbene single crystal with high crystalline quality (half peak width of rocking curve of 46.58 arcsec) and size of more than 60 mm. Then we fabricated crystal wafers for the first time to conduct systematic physicochemical measurements to reveal the intrinsic properties of the material. The high-quality single crystals were found to possess high optical transmittance (80%), fast decay time of 2.85 ns (68.49%) and high photoluminescence quantum yield (90.5%), which are more suitable for fast neutrons detection requirements. Thirdly, we conducted a comprehensive exploration of the radiation response of high-quality trans -stilbene single crystals to alpha particles and gamma rays. The results showed a record neutron/gamma discrimination performance with a FOM value of 4.33, which is the highest reported value so far. This work paves the way for practical applications of trans -stilbene and may provide guidance for the selection of detectors for monitoring ionizing radiations under multiple irradiations background. • Large-sized and high-quality trans -stilbene single crystals were grown by our independently designed growth equipment. • The fabrication of wafers from the as-grown single crystals were firstly realized to measure the physical/chemical properties. • The n/γ discrimination of trans -stilbene single crystals showed a FOM value of 4.33, which is the highest value so far. [ABSTRACT FROM AUTHOR]

The detection of fast neutrons is regarded technically challenging because the interaction probability of fast neutron with matter is extremely low. Based on our recent development of hexagonal boron nitride (BN) semiconductor thermal neutron detectors with a record high efficiency of 59%, we report here the feasibility studies of BN detectors for detecting fast neutrons. A BN detector with a detection area of 2.1 cm2 was fabricated from a 90 μm thick BN epilayer. In the presence of a bare Cf-252 source emitting fast neutrons ranging from 1 to 9 MeV, the detection efficiency was estimated to be about 0.1%. The measured mean free path of fast neutron in BN is about 7.6 cm. Together with the capability of BN for thermal neutron detection, the present results indicate that by incorporating BN with a large thickness, BN neutron detectors are expected to possess the unique capability of directly detecting thermal to fast neutrons as well as outstanding features resulting from the ultrawide bandgap of BN. The identification of a single material that is sensitive to both thermal and fast neutrons is valuable for the development of novel neutron detection technologies. [ABSTRACT FROM AUTHOR]

A special group of luminescence materials are scintillators for thermal neutron detection. Due to the properties of neutrons (contrary to e.g. electrons or gamma photons), a different approach has to be utilized—the high content of atoms with the sufficient absorption cross‐section toward neutrons and lower material density are needed. This work pursues a basic study of LiSrBO3 and LiSr4(BO3)3 doped with cerium or europium—materials promising as thermal neutron scintillators. These borates exhibit promising properties such as the high content of lithium and boron, suitable density, and proper environment for luminescent ions. Radioluminescence of these ceramic borates doped with cerium and europium was examined and promising samples were further characterized by photoluminescence spectroscopy and radioluminescence and photoluminescence kinetics measurement. The radioluminescence study of these borates is published for the first time. Cerium‐doped borates, in particular, exhibit a very promising response to an X‐ray excitation. [ABSTRACT FROM AUTHOR]

The effect of pulse pile-up on neutron count rates is a persistent challenge in photon active interrogation. During active interrogation, the neutron signatures from illicit special nuclear material (SNM) can provide a characteristic signal; however, the intense radiation environment can cause pulse pile-up in detectors. Organic scintillator detectors are favorable in active interrogation due to their fast neutron efficiency and fast timing characteristics and rely upon pulse shape discrimination to compare pulse shapes and classify detection events. Pile-up events are typically rejected during the analysis process because the pile-up events result in pulses with relatively large tail integrals, which appear similar to single neutron pulses. Pile-up events can be identified and removed in postprocessing, but in photon active interrogation scenarios, pile-up rejection algorithms can degrade due to the high pile-up rates, leading to erroneously high neutron count rates. Thus, it is essential that pulse pile-up events are minimized to produce accurate results. In this work, we compare the performance of a pair of 6-mm trans-stilbene cubes to a 5.08-cm-diameter, 5.08-cm-height trans-stilbene cylindrical detector during photon active interrogation. We use a Varex electron linear accelerator (linac) to produce an interrogation beam of bremsstrahlung photons up to 9 MeV in energy, which induces photofission and photodisintegration in depleted uranium (DU). We first optimize the pulse shape parameters for the 6-mm stilbene cubes using 137Cs and 252Cf sources and deploy the detectors in an active interrogation environment. As expected, the smaller detectors experience significantly less pile-up than the 5.08-cm stilbene cylindrical detector due to the reduction in detection volume. The 6-mm stilbene detectors observe a 250 ± 24 s−1 net neutron count rate and could determine the presence of the $\approx 2.8$ -kg DU in less than 3 min of measurement time, in stark contrast to the 5.08-cm stilbene detectors that failed to identify a net increase in neutron count rate due to the significantly high proportion of pile-up pulses. This work demonstrates that small detectors are robust against pile-up in photon active interrogation scenarios while maintaining a satisfactory neutron detection efficiency. [ABSTRACT FROM AUTHOR]

The Nevada National Security Site (NNSS), together with Los Alamos National Laboratory (LANL) and Lawrence Livermore National Laboratory, is developing a novel diagnostic to measure the reactivity of subcritical experiments (SCEs). This capability is known as neutron-diagnosed subcritical experiments (NDSEs). The decay of the fission gamma rays from the neutron-interrogated SCE is measured as a function of time with a large ($\sim 3$ -m diameter) detector wall consisting of 151 individual detector pixels. The data from this current mode measurement inform the neutron multiplication factor, $k_{\mathrm {eff}}$ , and thus the relative reactivity of the SCE. The NNSS developed the Gamma Array Simulation Toolkit (GAST) initially to help inform the design of the individual detector pixels and the 3.4-m diameter detector wall to be fielded as part of NDSEs. This toolkit is now being used to simulate and predict the performance of the final design of the individual detector pixels and the aggregate detector wall. Key detector characteristics evaluated from these simulations include impulse response, pulse height spectrum, number of photoelectrons per MeV, detector efficiency, and crosstalk between detector pixels. Collectively, the results of these simulations inform how well the fission gamma-ray die-off distribution from an NDSE measurement can be resolved. This is critical to determining the relative reactivity of the experiment. Furthermore, the GAST can be used to aid in the analysis of the experimental data from an NDSE measurement once the simulation has been benchmarked. [ABSTRACT FROM AUTHOR]

In this work, we propose a prototype of a compact detector assembly capable of discriminating between neutrons and gamma rays, by performing pulse shape analysis. The device takes advantage of recent improvements in silicon photomultiplier (SiPM) technology and the excellent neutron/gamma-ray discrimination capabilities of new plastics and standard liquid scintillators. Our work is focused on the read-out of small-, medium-, and large-sized organic scintillators with large-area SiPM arrays ($4 \times 4$ NUV and RGB-SiPM arrays, 17 mm $\times$ 17 mm). In particular, we used EJ-276 (and its old version EJ-299) and EJ-276G plastic scintillators of several sizes (ranging from 20- to 50-mm diameter) and two large liquid scintillator cells (EJ-301 and EJ-309, 50 mm diameter $\times 50$ mm thickness). Moreover, we show the comparison of neutron/gamma-ray discrimination performance between SiPM and standard photomultiplier read-out configurations. The presented innovative device could be used in different fields, first in fundamental nuclear physics experiments, as an ancillary neutron detector for the active target at the selective production of exotic species (SPES) facility at the Legnaro National Laboratories in Italy. Additionally, it could be used in radiation monitoring applications, as a fast neutron/gamma-ray counter to be embedded in unmanned vehicles for radiation monitoring. [ABSTRACT FROM AUTHOR]

This work addresses the use of plastic scintillators as an alternative to 3He neutron detectors for radioactive waste drum characterization. The time response of scintillators is three orders of magnitude faster than that of gas proportional counters, and they offer similar neutron detection efficiency at lower cost. However, they are sensitive to gamma rays and the neutron-gamma pulse shape discrimination (PSD) is not possible with standard PVT scintillators. The proposed approach uses the neutron and gamma times of flight in triple coincidences recorded with 252Cf, AmBe, and 60Co sources. A 2-D histogram of time delays between the second and first detected pulses, on the $x$ -axis, and between the third and second pulses, on the $y$ -axis, evidences a specific region of interest for spontaneous fission coincidences. MCNPX-PoliMi simulations are performed, which are in good agreement with previous experiments and allow for investigating the types of coincidences ($\gamma \gamma \gamma $ , nnn, $\gamma $ nn, $\gamma \gamma \text{n}$) and optimizing the rejection of neutron and gamma scattering crosstalk. The method was also experimentally tested with a 118-L mock-up drum filled with a metallic or an organic matrix, showing a correct estimation of the net fission signal up to an “alpha ratio” of 12 between fission and ($\alpha $ ,n) neutron emissions. Matrix and localization effects were also measured, showing a sensitivity (useful signal per gram of 240Pueq) for a homogeneous distribution of plutonium in the iron matrix about three times larger than in the wood matrix, due to neutron slowing-down in the latter. This difference can be taken into account by the prior knowledge of the matrix characteristics or by neutron and gamma attenuation measurements. In contrast, in case of a point source with an unknown position in the matrix, the relative localization uncertainty is 26% for the metallic drum, and 41% for the organic one. [ABSTRACT FROM AUTHOR]

We report the investigations made on the use of pixelated plastic scintillator (PS) and silicon photomultipliers (SiPMs) array applied to coded aperture gamma-neutron imaging. Specifically, verification of the ability of a multiplexing readout to discriminate and localize neutron interactions was studied. In its intended configuration, the gamma-neutron imager design consists of a coded aperture aligned with a matrix of $12\times12$ PS each coupled to a SiPM. The coded aperture is a rank 7 modified uniformly redundant array (MURA), composed of 1.2 cm of tungsten, with a surface area of 100.4 mm $\times100.4$ mm and placed at 5 cm from the detector. The pixelated PS is composed of polystyrene and standard fluorophores (20 wt% PPO, 0.03 wt% POPOP) loaded with a lithium carboxylate (Li $\alpha $ -valerate), which allows the triple discrimination between thermal neutrons, fast neutrons, and photons. Each pixel of PS has a dimension of 3.6 mm $\times3.6$ mm $\times3.6$ mm and they are separated from each other by 0.6 mm of polytetrafluoroethylene (PTFE). The photonic and electronic readout consists of the ArrayC-30035-144P SiPM from SensL, Cork, Ireland, connected to the diode coupled charge division readout from AiT. First, this neutron imager design was modeled and simulated using the MCNP6 Monte Carlo code. The encoding capability, field of view, and spatial resolution of the neutron imager were therefore evaluated by simulation. Then, we detailed the experimental setups implemented to demonstrate the feasibility of coupling pixelated PS to SiPM to localize radioactive sources and showed the results obtained. Finally, based on this position-sensitive gamma-neutron detector, a gamma-neutron imager was prototyped and tested. [ABSTRACT FROM AUTHOR]

Anisotropic scintillators can offer a unique possibility to exploit the so-called directionality approach to investigate the presence of those Dark Matter (DM) candidates inducing nuclear recoils. Their use can overcome the difficulty of detecting extremely short nuclear recoil tracks. In this paper, we present recent measurements performed on the anisotropic response of a ZnWO4 crystal scintillator to nuclear recoils in the framework of the ADAMO project. The anisotropic features of the ZnWO4 crystal scintillators were initially measured with α particles; those results have also been confirmed by the additional measurements presented here. The experimental nuclear recoil data were obtained using a neutron generator at ENEA-Casaccia and neutron detectors to tag the scattered neutrons; in particular, the quenching factor values for nuclear recoils along different crystallographic axes have been determined for three different neutron scattering angles (i.e. nuclear recoils energies). The anisotropy of the light response for nuclear recoils in the ZnWO4 crystal scintillator has been determined at 5.4 standard deviations. These results open the possibility to realize a pioneering experiment to investigate the above-mentioned DM candidates by means of the directionality. [ABSTRACT FROM AUTHOR]

Due to the shortage of the 3He gas and its rapidly increasing price, scintillator detectors, the advantages of which are high spatial resolution and capability of detection in real time, become widely used in many neutron instruments. In this work, a position-sensitive neutron detector consisting of a 6LiF/ZnS scintillation screen and a silicon photomultiplier array linked to a capacitive network to detect the positions of incident neutrons, is constructed and tested. To evaluate the detector performance, a series of neutron beam experiments with the detector prototype were performed in the BL20 at the China Spallation Neutron Source. The spatial resolution was measured, and the energy-selective neutron imaging and Bragg edge measurements of a 316L stainless steel sample were performed. A sub-millimeter spatial resolution could be obtained for the detector prototype under study. The detector with such a high spatial resolution is promising for applications in neutron scattering experimental installations, especially for neutron single-crystal diffractometers. [ABSTRACT FROM AUTHOR]

Neutron imaging is a powerful tool for observing the internal structure of an object without destroying the object. Neutron imaging (neutron radiography) is a prominent application of neutrons but still requires significant improvements, for example, in sensitivity, resolution, radiation hardness, and handling of neutron imaging detectors. This paper presents the development and the first neutron imaging results of a neutron flat-panel detector (nFPD) based on an In–Ga–Zn–O (IGZO) thin-film transistor (TFT)/photodiode array coupled with a LiF/ZnS scintillator sheet. Direct photo-coupling to the scintillator increases the light collection efficiency. Moreover, unlike lens-coupled neutron cameras, the proposed detector is compact and easy to handle. Owing to the high off-state resistance of IGZO TFTs, their leakage current is lower than that of conventional TFTs, enabling the IGZO TFTs to hold an accumulated charge for a longer period of time and allowing longer exposure times for imaging. This would be a powerful feature for imaging at compact neutron sources with limited flux. This paper reports on the first neutron imaging results with an IGZO nFPD, its performance evaluation, and a demonstration of three-dimensional computed tomography with neutrons. [ABSTRACT FROM AUTHOR]

Gamma/neutron dual detection has occupied significant territory in the field of homeland security and nuclear energy development. Cs2LiLaBr6 (CLLB) has shown both neutron/gamma dual-mode detection capability and excellent scintillation properties. Herein, we explored the Cs2LaBr5-LiBr phase diagram through powder X-ray diffraction (XRD) and differential scanning calorimetry (DSC) tests of synthesized polycrystalline materials. The Cs2LaBr5-rich side of the phase diagram is similar to a binary peritectic phase diagram, where the peritectic line (447 °C) extends to a LiBr content of 61%. The LiBr-rich side of the phase diagram resembles a binary eutectic phase diagram, where the eutectic point (395 °C) is located at 80% LiBr concentration. Guided by the phase diagram, CLLB ingots were designed to grow from the LiBr-rich side with different concentrations of LiBr. The scintillator properties of CLLB crystals were found to be deteriorated by the increasing defects with elevated LiBr contents. A concentration of LiBr around 55% was a preference for the growth of high-quality CLLB. A better understanding of the Cs2LaBr5-LiBr phase diagram benefits the growth of CLLB crystals and provides considerations for other halide double perovskites. [ABSTRACT FROM AUTHOR]

Lithium iodides are very efficient single‐crystal scintillators for thermal neutron detection. Doping with silver, as activator ions, has shown to improve its limitation of discriminating gamma background by introducing pulse shape discrimination ability. To improve the scintillation performance, single crystals of LiI:Ag, codoped with different concentration of Sr ions, are grown and characterized in details. A systematic investigation of radioluminescence, thermoluminescence, and scintillation properties along with the decay kinetics provides better understanding about the role of defect structure in scintillation mechanism. The extra charge, provided by Sr2+ ions, is found to alter the defect structure with relative reduction of the contribution from the deeper trap centers in comparison with the shallow traps. Consequently, it leads to a significant improvement of light yield quenching under higher excitation density of charged particle irradiation. The 0.1% Sr codoped crystals provide a better discrimination ability of neutron and gamma radiations for simultaneous detection. [ABSTRACT FROM AUTHOR]

A Cs 2 LiYCl 6 (CLYC) scintillation crystal is a promising candidate for fast neutron spectroscopy due to its dual mode gamma/neutron capability and good energy resolution. Despite promising features, CLYC's limited radiation tolerance and inability to separate alpha/proton particles using pulse shape discrimination (PSD) method restrict its applicability in fast neutron spectroscopy. The significant cross-sections for 35Cl(n,p)35S and 35Cl(n, α)32P reactions make 35Cl-containing crystals attractive candidates for fast neutron detection, prompting their development as a promising new solution. This study reports the growth of LaCl 3 crystals via the Bridgman technique, enabling further exploration of their scintillation and material properties for fast neutron detection applications. The effects of the proton irradiation on LaCl 3 crystals were investigated by irradiating them with a 100 MeV proton beam at the Korea Multi-purpose Accelerator Complex. The study quantified radiation damage by comparing the pre- and post-irradiation scintillation properties and PSD of the LaCl 3 crystals. The results of the measurements demonstrate that LaCl 3 crystals are promising candidates for applications in fast neutron identification, spectroscopy, and space mission, maintaining performance even under high-radiation environments. • Good alpha/proton separation capability of undoped LaCl 3 crystals. • We successfully grew undoped LaCl 3 crystals up to a size of 38 Φ mm x 25 mm. • Scintillation properties of the crystals showed good agreement with published values. • Direct unfolding method was achieved for fast neutron measurements. • Radiation hardness of LaCl 3 crystals was confirmed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Growth of a crack-free, optical transparent, and large-size trans -stilbene (TSB) single crystal using novel vaporized purification method is reported. • The crystal also exhibits strong blue emission (380 nm) in photoluminescence and emission at 387 nm under X-ray radiation in radioluminescence spectroscopy. • The scintillation decay time is calculated to be 6 ns under 137Cs gamma source. • The figure of merit of 2,4 indicates its potential significance in fast neutron detection with efficient PSD property. The paper reports the successful growth of large, crack-free trans -stilbene (TSB) single crystals using an in-house developed vertical Bridgman setup. The material purification involved a novel vaporized method at 130 °C. Parameters like furnace setup and ampoule's cone angle were optimized during the growth process. The Powder XRD pattern confirms the phase of material and crystallinity. The crystal exhibited high transmittance (78 %) in the visible region, with an optical band gap of 3.4 eV. Photoluminescence study indicated strong blue emission at 380 nm, with radioluminescence spectroscopy showing emissions at 387 nm under X-ray radiation. The crystal exhibited a scintillation decay time of 6 ns under 137Cs gamma source, highlighting its fast decay and efficient PSD property with a figure of merit of 2.24 for fast neutron detection applications. [ABSTRACT FROM AUTHOR]