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Large area thermal neutron detectors are applied in many fields including industrial imaging, nuclear safeguarding, neutron scattering, and fundamental science. Historically, these detectors were based on 3He gas proportional counters despite the limitations of 3He detectors such as high cost, limited supply, non-uniform spatial resolution, and depth of absorption problems. Two alternatives to 3He detectors are 6Li-loaded glass scintillators, and powdered ZnS(Ag) scintillators mixed with 6LiF neutron converters. The 6LiF/ZnS(Ag) scintillator has advantages over 6Li glass as it is less expensive and can be produced in larger areas, although its self-absorption presents a problem. In this work, we developed a large area thermal neutron detector based on 6LiF/ZnS(Ag) scintillator coupled with wavelength shifting fibers. The detector uses resistive charge divider-based position encoding. We further modified and improved the method by 2D segmentation of the detector using modular multichannel readout electronics. This segmentation approach allows for a combination of large detector area, improved spatial resolution, and increased count rate. Furthermore, spatial resolution can be variable across the detector area by adjusting the segment size. [ABSTRACT FROM AUTHOR]

Muography using cosmic ray muons is a non-invasive and environmentally friendly imaging technique with comprehensive applicability across various fields such as mineral exploration, archaeology, and engineering, etc. Given characteristics of high penetration and broad energy spectrum of cosmic ray muons, three-dimensional density distribution of objects up to hundreds of meters can be well reconstructed. In mineral exploration and archaeology applications, conventional planar detectors are too large and usually deployed in spacious rooms like tunnels or outdoors, which seriously limits the deeper and broader applications of muography. A type of borehole muon detector is highly desired to address this. In the work, we introduce a novel borehole-type muography detector comprising annular and prismatic plastic scintillators, allowing for its deployment in boreholes. In the paper, the structural design of the detector is described in details and its performance is evaluated numerically and experimentally. Comprehensive investigation on components and on the system as a whole were conducted. According to our commissioning tests, the detector we propose has an omnidirectional field of view without blind spots, with an angular uncertainty of 27.4 mrad and a position uncertainty of 2.29 mm in the azimuthal direction, an angular uncertainty of 20.6 mrad and a position uncertainty of 10.31 mm in the zenithal direction. Detection efficiencies for both annular and prismatic scintillators were measured as 90.3 ± 0.53% and 92.27 ± 0.82%. In addition, an underground location was investigated, survival rate distributions being calculated from above-ground and underground measurements. The results indicate its capability to successfully address muography applications This novel borehole-type detector has the potential to address industry demand for lower-cost, more flexible muography solutions. • Achieves high angular resolution and full 360° omnidirectional detection within a compact borehole-sized format. • Maintains >90% detection efficiency across scintillator sections. • Utilizes a simplified single-ended readout design with fewer electronic channels. • Employs low-cost, easy-to-process plastic scintillators as the primary component. [ABSTRACT FROM AUTHOR]

It is important to differentiate between natural and artificial radioactive materials such as plutonium in nuclear facilities. In this study, a scintillator-based alpha-particle detector was developed using YAP:Ce scintillator and Multi-Anode PhotoMultiplier Tube. The detector was used to measure various naturally occurring radioactive materials (NORM) samples including radon progeny, lead plate, lantern mantle, and radium ceramic ball. The measurement results were compared with Monte Carlo simulation calculations and were found to be in agreement. The energy resolution of the detector is 8.6%FWHM. In the measurement results of radon progeny, peaks of 212Bi (6.1 MeV), 214Po (7.7 MeV), and 212Po (8.8 MeV) can be observed. The lead plate contains 210Po and emits 5.3 MeV alpha particle. The simulation with the same energy was able to reproduce the actual measurement. The results showed the energy and distribution of the alpha particles emitted by the NORM samples. The study successfully demonstrated the capability of the developed alpha-particle detector in identifying NORM. [ABSTRACT FROM AUTHOR]

We report on the development of a custom particle detection system that aims to improve the detection capabilities of the ROSPHERE array. The detector is designed specifically for lifetime measurements using the in-beam Fast-timing method for nuclear states in nuclides produced in nuclear transfer reactions. An 80 x 3.6 mm disc of BC400 plastic scintillator was coupled to a sparse SiPM array readout connected to a dedicated Front End Electronics board. The detector was tested versus a conical LaBr 3 (Ce) coupled to a Hamamatsu PMT readout. The timing measurements resulted in a resolution of 896(5) ps. The detector design, characteristics, and performances are presented in this paper along with future improvements. [ABSTRACT FROM AUTHOR]

High-speed X-ray imaging can be used to observe the internal evolution of objects in the microsecond range. However, obtaining data and processing images continuously are difficult when the speed of X-ray imaging is more than one million frames per second (fps). The novel method of high-speed X-ray imaging, which is based on a SiPM auto-encoding detector, was proposed. The different response to X-ray is realized by adjusting the bias voltage of different pixels to encode the analog signals. The analog signals from multiple SiPM pixels are simplified into a single signal. In this way, SiPM is constructed as the SiPM auto-encoding detector, which greatly reduces the amount of analog signals to be sampled for each frame of X-ray image, and then the image is reconstructed in the upper computer. The feasibility of the imaging method was verified by coupling the pixelated SiPM and lutetium-ytterbium scintillation crystals to construct a SiPM auto-encoding detector. Six patterns were exposed when pulsed X-rays were performed at frequencies of 100 and 500 kHz. Then, the number of image pixels was compressed from 16 to 4. The peak signal-to-noise ratio of the reconstructed images was above 41, and the structural similarity was above 0.99. Experimental results demonstrated that the speed of continuous X-ray imaging reached 500, 000 fps for six kinds of 4 × 4 pixel patterns. This method can be applied to improve the speed of high-speed continuous X-ray imaging. [ABSTRACT FROM AUTHOR]

Gamma detectors consisting of lanthanum bromide (LaBr 3) scintillator and silicon photomultiplier (SiPM) have extensive applications in various scientific fields. Accurate gamma energy measurement depends on accurate calibration of these detectors. While some studies have attempted detector self-calibration based on the natural background of LaBr 3 , these methods are limited to specific LaBr 3 crystals and lack generality. To address this limitation, this paper proposes a self-calibration method that solely utilizes the natural radioactivity of 138La. By solving for the maximum similarity between the test background from measurement and the standard spectrum obtained from the Geant4 simulation, the detector is effectively calibrated. Furthermore, the application of a series of energy spectrum processing algorithms simplifies the solution complexity of the maximum similarity problem. Experimental results from four different crystals at varying temperatures demonstrate calibration errors of less than 0.8% at 662 keV, highlighting the method's broad applicability and accuracy. Besides, the influence of the background measurement time and the natural environmental background on the self-calibration method are discussed in detail, further illustrating the value of the application. [ABSTRACT FROM AUTHOR]

Signal saturation in the Silicon PhotoMultiplier (SiPM) often causes a serious problem in using a detector equipped with SiPMs for scintillator readout. Conventionally, SiPM signal saturation is measured through direct injection of visible light pulses to the SiPM. However, the method works poorly with the scintillation detector because the effects of the time constant of the emission of scintillation light are not included. Here, we present a novel method to measure the precise degree of SiPM signal saturation in scintillation detectors. The key difference from the conventional method is to use UV light pulses, as opposed to visible light ones, to inject and excite scintillation light in the detector. It allows us to directly measure the degree of saturation in situ taking into account all the major effects in the detector, such as the time constant of the scintillation emission. We also develop a new model for SiPM signal saturation and validate it with the measured degree of saturation with the above-mentioned new method. [ABSTRACT FROM AUTHOR]

Precise measurement under high counting rates has been a major challenge for γ -ray spectroscopy, where signals generally pile up with each other and their characteristic values are deeply coupled. An off-line pile-up pulse recovery algorithm based on template matching is developed for LaBr 3 scintillation detectors and has been applied to data from China Spallation Neutron Source (CSNS) Back-n white neutron beamline. As an improvement to the traditional Template Matching methods, the predetermined template shape is associated with pulse amplitudes, which is found crucial to achieve the best fitting results. Moreover, a universal strategy of setting the initial values of fitting allows to resolve signals that are separated in time by less than the characteristic rise time. Processing of simulated pulses demonstrates that the lower limit of interval to distinguish successive events is 10 ns, which is a significant improvement to the previous works. The algorithm performs well under a counting rate of 6 × 1 0 7 s−1, and is still effective up to 1 0 8 s−1. Analysis of experimental data indicates that this algorithm recovers over 98% count yield under a counting rates of no more than 4 × 1 0 6 s−1 in this work, providing a more reliable approach to deduce neutron-induced reaction cross sections. [ABSTRACT FROM AUTHOR]

A novel beam profiler based on microstructured scintillation resin is presented. The detector consists of a bundle of waveguides, featuring an active area of 30 × 30 mm 2 with a fill factor of 50% and a pitch of 400 μ m. This configuration is obtained by casting a scintillating resin into a microfabricated Polydimethylsiloxane (PDMS) mold. A prototype, coupled to an array of photodiodes and readout electronics, potentially allowing profile rates up to 7 kHz, has undergone testing with an ultraviolet (UV) source and a proton beam accelerated at different energies, typical of those employed in proton therapy. The experimental results obtained during the test campaigns were compared with theoretical simulations demonstrating a good agreement with the modeling expectations, thus confirming the validity of this novel design for microstructured scintillating detectors. [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]

In this work a new readout scheme for scintillator-based detectors, using discrete time differences through a delay line is proposed, reducing the readout channels while maintaining the spatial resolution. A prototype was built using plastic scintillator blocks and MPPC sensors. Currently, the prototype produces discrete distributions with a dispersion < 1. 1 ns which allows discriminating the different positions. The estimated spatial resolution is σ = 1. 456 mm. This value presents a better resolution than that of Time-of-Flight detectors and of the order of Segmented detectors, but uses fewer readout channels. It is expected to improve this resolution using interpolation effects and testing with larger scale instruments. [ABSTRACT FROM AUTHOR]

This article presents a novel application of the lutetium-yttrium oxyorthosilicate (LYSO) scintillator in a newly constructed neutral particle analyzer with a parallel electric and magnetic fields structure (E//B NPA). The LYSO scintillator, coupled to the silicon photomultiplier (SiPM) without a reflector, serves as the detector module in the E//B NPA. The LYSO+SiPM configuration offers numerous advantages for the NPA application, including high efficiencies, compact size, low voltage operation, and exceptional resistance to magnetic fields. The performance of a prototype detector module was studied using a radioactive source in conjunction with the 50 kV electron cyclotron resonance (ECR) ion source platform. The crosstalk of optical photons from adjacent detector modules was examined with two detectors, and it was determined to be negligible. The high-energy α spectra exhibited a distinctive two-shoulder structure, which arises from α particles impinging on different positions of the LYSO crystal surface. This observation was further investigated through Geant4 simulations. The detector module was found to have a low-energy limit of 10 keV for hydrogen ions. In the comprehensive measurements, linear energy responses were observed for α particles and hydrogen ions within the error bars. The relative light yield of α and hydrogen ions exhibited a different trend compared to that of γ rays or electrons, providing valuable insights for the study of non-proportionality of light yield for light ions in the LYSO scintillator. [ABSTRACT FROM AUTHOR]

Phoswich (phosphor sandwich) systems composed of ZnS(Ag) and plastic dual scintillators have the ability to distinguish α and β particles via digital pulse-shape discrimination. In this work, a novel logistic regression algorithm based on time–frequency features (LR-TF) is presented and evaluated for its ability to digitally discriminate α and β particles in a mixed field. The LR-TF algorithm employs the charge comparison method (CCM) and Fourier gradient analysis (FGA) to extract time–frequency features from pulse shapes, thereby constructing a logistic regression model. Training of the model is shown to enable the discrimination α and β particles. The CCM, FGA, and LR-TF were applied to thousands of pulses obtained with a data acquisition system based on a Phoswich coupled with a silicon photomultiplier. The experimental results show that the LR-TF algorithm provided the best overall performance with misidentification ratios of 1.9 % and 0.63 % for α particles and β particles, respectively, achieving a figure of merit of 4.30, and an area under the receiver operating characteristic of 0.996. [ABSTRACT FROM AUTHOR]

Radiological site remediation is a resource intensive process requiring extensive field sampling to demonstrate regulatory compliance. Specifically, the application of Monte Carlo (MC) simulations and automated hybrid radiation transport methods has garnered interest in streamlining the remediation process by simulating detector responses for a plurality of contaminated media, contamination depths and profiles, and source-detector orientations. In this study, experimental validation of gamma-ray detector efficiency responses was conducted for simulations of radiological site-specific and idealized external contamination conditions. Measurements were performed with a cylindrical 2′′ × 2″ sodium iodide thallium-doped (NaI(Tl)) scintillator detector suspended above a 217.8 kBq, 50 cm × 50 cm 137Cs contamination source located on the surface of or buried within environmental soil. New area correction factors (ACFs) and gamma shielding factors (GSFs) were also derived to modify the simulated idealized detector efficiency responses, accounting for reductions in source area and clean soil covering layers, respectively, that may be encountered when performing in-situ gamma spectrometry in the field. The study concluded that simulated total detection efficiency from energy deposition in the active volume of the detector crystal can be adopted for radionuclide screening purposes. Furthermore, pragmatic implementation of environmental surveying using gamma-spectrometry requires site-specific information. [ABSTRACT FROM AUTHOR]

In deep-underground experiments, intrinsic detector background can exceed the external one, limiting the detection sensitivity. Intrinsic background in liquid scintillator neutron detectors consists of α particles emitted from radioactive impurities in the detector housing (and possibly in the liquid). We present the results of long background measurements of 12 EJ-309 liquid organic scintillators detectors in the deep-underground Gran Sasso National Laboratory of the Italian Institute of Nuclear Physics. These detectors are a part of the detection array for the SHADES ERC project that aims to measure the very low cross section (down to picobarn) of the astrophysically important reaction 22 Ne (α , n) 25 Mg. With an exposure of ∼ 35 days we identify an actinide concentration in the detector housing of 8. 4 (1. 8) sta (1. 4) sys × 1 0 − 2 ppm and 1. 62 (0. 57) sta (0. 03) sys × 1 0 − 1 ppm of 238 U and 232Th, resulting in 64 α particle counts per hour. The half-life of 214Po was also determined as 163. 7 (11) μ s. [ABSTRACT FROM AUTHOR]

Scintillation radiation detectors based on silicon photomultipliers (SiPMs) are widely used nowadays both in various medical apparatus and physics experiments, e.g., in PET. At the same time, this technology has great potential in terms of creating X-ray photon counting detectors, which are in demand both in medicine and applied research. In this work, we investigate the influence of main SiPM parameters on the overall system performance, as well as different methods of data readout. It is shown that the use of SiPMs with shorter cell recovery time and larger number of microcells makes it possible to achieve a rate capability of 12 Mcps (mega counts per second) per channel. At the same time, the scintillator decay time is still among the limiting factors for such systems. [ABSTRACT FROM AUTHOR]

This work presents a systematic study of the properties (Light Output Non-Uniformity (LONU) and energy resolution) of two CsI(Tl) scintillation units over a span of almost three years, under adverse conditions of humidity and temperature. These two crystals are part of the CALIFA detector, a highly segmented calorimeter and spectrometer for γ rays and light-charged particles, that is placed surrounding the reaction target at Cave C, the experimental cave of the R 3 B (Reactions with Radioactive Relativistic Beams) collaboration at the GSI-FAIR facilities in Darmstadt, Germany. The findings obtained after the experiment indicate that there was no significant impact on the performance in terms of resolution and LONU. This suggests that the employed wrapping for light collection effectively serves as an excellent barrier against humidity. As a result, the crystal is preserved in a far better condition than initially anticipated. [ABSTRACT FROM AUTHOR]

New detectors for future high-energy physics experiments will operate under unprecedented radiation dose rates. This condition requires improved radiation resistance on detector equipment. The consequent development of new materials, particularly optical materials, becomes crucial. In this work, optical components mean reflectors, light absorbers, or light transmitters. These materials, reflectors or light transmitters, are needed in detectors primarily to collect and transmit light from the scintillator to the PMT. When it comes to light absorbers, they are required to protect the detector from light from the environment. This work aims at studying selected optical materials with improved properties (functional and optical) and radiation resistance that can be used in new detectors at the Large Hadron Collider (LHC) experiments. Light transmittance, optical reflection, thermal characteristics, and radiation resistance were investigated to evaluate the proposed materials. We have developed optical systems based on siloxanes to continue our previous developments of radiation-resistant materials for radiation detectors. We also report a study of several reflective materials and light absorber introduced into the siloxane. Investigations have shown that these systems are radiation resistant to doses of at least 1 MGy. Tested samples were irradiated at linear electron accelerator LUE-40 in the National Science Center Kharkiv Institute of Physics and Technology (KIPT). The accelerated electrons were sent to the heavy complex targets to deliver the irradiation with gamma or neutron fluxes. The consequent gamma and neutron fluxes and doses were estimated with the GEANT4 simulation. [ABSTRACT FROM AUTHOR]

BlueSTEAl, the Blue (aluminum chamber of) Silicon TElescope Arrays for light nuclei, has been developed to study direct reactions in inverse kinematics, as well as scattering and breakup reactions using radioactive ion beams. It is a detector system consisting of a pair of annular silicon detector arrays and a zero-degree phoswich plastic scintillator. For typical binary reaction studies in inverse kinematics, light ions are detected by the Si array in coincidence with heavy recoils detected by the phoswich placed at the focal-plane of a zero-degree magnetic spectrometer. The Si array can also be used to detect light nuclei such as beryllium and carbon with clear isotope separation, while the phoswich can also be placed at zero degrees without a spectrometer and used as a high-efficiency beam counting monitor with particle identification capability at the rate of up to ∼ 5 × 104 particles per second. This paper reports on the capabilities of BlueSTEAl as determined by recent experiments performed at the Texas A&M Cyclotron Institute. The device is also anticipated to be used in future experiments at other radioactive ion beam facilities. [ABSTRACT FROM AUTHOR]

The challenge of simultaneous measurement of neutrons and gamma rays with good resolution has potential impact on numerous applications in, for example, national security. Here, we employ a phosphor-sandwich style detector, combining Gadolinium-Aluminium-Gallium-Garnet (GAGG(Ce)) and Cerium-Bromide (CeBr 3) scintillators with a silicon photomultiplier for photodetection. Through pulse-shape discrimination (PSD), we are able to distinguish thermal neutron capture on the gadolinium from γ -ray detection in the CeBr 3 with a figure-of-merit in the region-of-interest of 1.406(5). In agreement with previous work we demonstrate that an improved signal-to-background can be achieved through the use of very thin GAGG(Ce) crystals, while also demonstrating the importance of the detector geometry in reducing the low-energy background. [ABSTRACT FROM AUTHOR]

We successfully developed 20- and 40-wt% HfO 2 -nanoparticle-loaded plastic scintillators (Hf-PLSs), and subsequently, assembled X-ray timing scintillation detectors using the Hf-PLSs and silicon avalanche photodiodes (Si-APDs) as the photodetector. Two types of Si-APDs were examined for two different detectors. A proportional-mode APD (pAPD) exhibited a nanosecond response, but a relatively low internal gain of less than several hundred. By contrast, a Geiger-mode APD exhibited a high gain of 105−6, but its output pulse width was longer than several tens of nanoseconds; the pixelated device is called as SiPM. A pAPD (Hamamatsu Photonics S8664-4433, 3 mm in diameter) was used as the photodetector and was combined with 20 wt% Hf-PLS (∼3 mm cube) as the X-ray scintillation timing detector. A SiPM (Hamamatsu Photonics S13360-3025, 3 mm × 3 mm) was assembled with 40 wt% Hf-PLS (∼3 mm cube). The characteristics of the two types of scintillation timing detectors were evaluated using a 57.61-keV synchrotron X-ray beam to assess their applicability in nuclear resonant scattering experiments. Both the detectors were cooled down to −35 or −20 °C to reduce noise and obtain a higher APD gain. A good time resolution of (0.31 ± 0.04) ns (FWHM) was easily obtained with the SiPM detector using a large APD gain at −20 °C, although the time resolution of the pAPD detector finally reached (0.39 ± 0.04) ns (FWHM) at −35 °C owing to a small gain of 146. However, a maximum count rate of over 1.4 × 107 s−1 was observed owing to the fast response of the pAPD detector, whereas the SiPM detector exhibited a maximum count rate of 5.9 × 106 s−1 because of the long pulse tail of ∼30 ns. [ABSTRACT FROM AUTHOR]

In order to improve the temporal response of SiC-HPMTs, a new SiC detector with a faster time response (leading edge 1.5 ns, FWHM 4 ns) was developed for constructing an improved SiC-HPMT. Then the properties of the improved SiC-HPMT were studied in detail. Compared with those of the previous SiC-HPMT, the temporal response of the improved SiC-HPMT, with a leading edge of about 2 ns and a FWHM of less than 5ns was effectively improved. The maximum linear current that exceeded 630 mA depends on both the accelerating and focusing voltage (V a) and the bias voltage (V SiC) of the SiC detector, but has a strong dependence on V a. The scintillation detector comprised of the improved SiC-HPMT and an EJ228 scintillator can accurately obtain the multiple peaks characteristic of the pulsed X-ray source, which indicates that the improved SiC-HPMT can well satisfy the requirements for measuring the time information of fast pulsed radiation fields. In addition, the SiC-HPMT should be placed at the position that deviates from the radiation beam to avoid the direct irradiation on the SiC detector. The improved SiC-HPMT will further expand its application in pulsed radiation field measurements and become a supplement for existing photoelectric detectors. [ABSTRACT FROM AUTHOR]

Most detector systems used for positron emission particle tracking (PEPT) are very expensive due to the use of inorganic plastic scintillators combined with a high number of readout electronic channels. This work aims to reduce the overall cost of a PEPT-capable detector system by using large and cost-effective plastic scintillators and developing custom 2 × 2 silicon photomultiplier (SiPM) arrays, preamplifiers, and discriminators. The use of long (20 mm × 20 mm × 1000 mm) plastic scintillator bars read out with photodetectors only at their respective ends allows an overall smaller number of photodetectors and associated readout electronics, which in turn reduces the overall cost of the system. In addition, the development of a custom SiPM array and preamplifier allows a free selection of interconnection and readout, as most commercial producers only offer specific types of interconnections and therefore lack other connections such as serial or hybrid. Thus, several common circuit types for SiPMs and preamplifiers were tested and compared in this work, and it was found that a serial connection implemented in a hybrid interconnection for the SiPMs and an inverting preamplifier based on a high-frequency operational amplifier provided the best results for the proposed detector system. Measured with a 22Na source, the combination of SiPM array and preamplifier led to a rise time of 3.7 ns and a signal amplitude of 175 mV. [ABSTRACT FROM AUTHOR]

The outer water buffer is an economic option to shield the external radiative backgrounds for liquid-scintillator neutrino detectors. Since the refractive index of the liquid scintillator is larger than that of water, the consequential total internal reflection of scintillation light at the media boundary introduces extra complexity to the detector optics. This paper develops a precise detector-response model by investigating how total internal reflection complicates photon propagation and degrades reconstruction. We first parameterize the detector response by regression, providing an unbiased energy and vertex reconstruction in the total internal reflection region while keeping the number of parameters under control. From the experience of event degeneracy at the Jinping prototype, we identify the root cause as the multimodality in the reconstruction likelihood function, determined by the refractive index of the buffer, detector scale and PMT coverage. To avoid multimodality, we propose a straightforward criterion based on the expected photo-electron-count ratios between neighboring PMTs. The criterion will be valuable for the success in future liquid-scintillator detectors by guaranteeing the effectiveness of event reconstruction. [ABSTRACT FROM AUTHOR]

In the R 3 B experiment at FAIR, charged particles with energies up to 600 MeV and forward boosted γ -rays with energies up to 20 MeV need to be detected in scattering experiments. Calorimeters for nuclear physics experiments of this kind, using relativistic radioactive ion beams, require high energy resolution and high efficiency for simultaneous detection of strongly Doppler shifted γ -rays and high-energy charged particles. A calorimeter design that can meet these requirements, using CsI(Tl) scintillators, results in detector elements that may exhibit light output variations with crystal depth, which can limit the attainable resolution. In this paper we present results from a systematic study of 478 detector modules of CALIFA, the R 3 B calorimeter, in order to determine and minimize such variations. To facilitate further systematic studies we also present results for the total absorption length of the scintillation light, using spectrophotometry, light crosstalk between adjacent detector modules, and surface topography of the CsI(Tl) crystals from atomic force microscopy. [ABSTRACT FROM AUTHOR]

Enhancements in gamma-ray spectral resolution have been realized through hardware development, including low-defect scintillation materials, solid-state detector technology, and low-noise read-out electronics. Enhanced resolution has also been provided by deconvoluting hardware response through the application of spectral unfolding techniques. However, fusing data from multiple independent measurements, both before and after spectral unfolding, to obtain more information than exists from a single measurement represents a largely unexplored path. This work provides a statistical foundation from which data acquired from an arbitrary number of independent gamma-ray spectra can be fused to yield higher resolution than the constituent measurements yield in isolation. Specifically, three data fusion techniques are considered: (i) pulse-height spectrum fusion, (ii) unfolded fluence linear opinion pool, and (iii) unfolded fluence logarithmic opinion pool. We explore the qualitative characteristics of these methods. We then apply them to spectra of thallium-doped sodium iodide [NaI(Tl)] and bismuth germanate (BGO), where all spectra are provided by MCNP simulations. Our results demonstrate improved resolution, thus establishing the methods as an inexpensive alternative to hardware upgrades. Moreover, our results demonstrate that these results have the potential to expand the capability of cutting-edge technology to provide currently unachievable resolution. [ABSTRACT FROM AUTHOR]

We report on the design and performance of the LUX-ZEPLIN (LZ) "Screener", a small liquid scintillator detector consisting of ≈ 23 kg of LAB-based gadolinium-loaded liquid scintillator (GdLS) to be used in the LZ Outer Detector. The Outer Detector will be filled with 17.3 tonnes of GdLS and will surround the central liquid xenon time projection chamber of LZ. Its primary function will be to tag neutron events in the liquid xenon which could mimic a WIMP dark matter signal. To meet the deadtime requirements for the Outer Detector, the radioimpurity levels in the GdLS must be kept below ≲ 0. 07 mBq/kg. This background level corresponds to a rate of ≈ 50 Hz above an energy threshold of 100 keV. The Screener was operated in the ultra-low-background environment of the former LUX water shield in the Davis Laboratory at the Sanford Underground Research Facility for radioassay of the GdLS. Careful selection of detector materials and use of ultra-low-background PMTs allows the measurement of a variety of radioimpurities. The 14 C / 12 C ratio in the scintillator is measured to be (2. 83 ± 0. 06 (stat.) ± 0. 01 (sys.)) × 1 0 − 17. Use of pulse shape discrimination allows the concentration of isotopes throughout the 238 U , 235 U , and 232 Th chains to be measured by fitting the collected spectra from α and β events. We find that equilibrium is broken in the 238 U and 232 Th chains and that a significant portion of the contamination in the GdLS results from decays in the 227 Ac subchain of the 235 U series. Predictions for the singles rate in the Outer Detector are presented. The rate from radioimpurities above 100 keV in the GdLS is estimated to be 97. 9 ± 6. 4 Hz , with 65. 5 ± 1. 9 Hz resulting from α -decays. [ABSTRACT FROM AUTHOR]

A newly developed segmented YSO scintillator detector was implemented for the first time at the RI-beam Factory at RIKEN Nishina Center as an implantation-decay counter. The results from the experiment demonstrate that the detector is a viable alternative to conventional silicon-strip detectors with its good timing resolution and high detection efficiency for β particles. A Position-Sensitive Photo-Multiplier Tube (PSPMT) is coupled with a 48 × 48 segmented YSO crystal. To demonstrate its capabilities, a known short-lived isomer in 76Ni and the β decay of 74Co were measured by implanting those ions into the YSO detector. The half-lives and γ -rays observed in this work are consistent with the known values. The β -ray detection efficiency is more than 80 % for the decay of 74Co. [ABSTRACT FROM AUTHOR]

A novel fast-cured, boron-loaded, plastic organic scintillator was developed and characterized. A diisopropylnaphthalene-containing scintillator was manufactured in minutes with the addition of two commercially available fast-curing monomers, isobornyl acrylate (IBOA) and 1,6-Hexanediol dimethacrylate (HDDMA). The light yield of the device was measured to be approximately 70% relative to a similarly sized, but several-year-aged, EJ-276 detector. Using a coincidence capture technique, the neutron capture light output was found to be 87.7 ± 4.2 keVee, which was 1.47 ± 0.07 greater than the light output from a 59.5 keV electron. Producing a viable fast-cured and thermal-neutron-sensitive detector enables the capability to pursue cost-effective 3D printed thermal neutron detectors in a timely manner. [ABSTRACT FROM AUTHOR]

A characteristic of every inorganic scintillator crystal is its light yield, i.e., the amount of emitted scintillation photons per unit of energy deposited in the crystal. Light yield is known to be usually non-linear with energy, which impacts the spectroscopic properties of the scintillator.Cerium-doped gadolinium–aluminium–gallium garnet (GAGG:Ce) is a recently developed scintillator with several interesting properties, which make it very promising for space-based γ -ray detectors, such as in the HERMES nanosatellite mission. In this paper we report an accurate measurement of the GAGG:Ce non-linearity in the 20–662 keV γ -ray energy interval, using a setup composed of three samples of GAGG:Ce crystals read out by Silicon Drift Detectors (SDDs). [ABSTRACT FROM AUTHOR]

A prompt gamma-ray detector for measuring the boron-10 concentration in real time for boron neutron capture therapy was researched. Our previous detector, which comprised a scintillator made from a slab of LaBr 3 (Ce) and an 8 × 8 array multi-pixel photon counter (MPPC), discriminated between 478 keV and 511 keV gamma rays. However, the spatial resolutions of the detector were not applicable to the detection of the boron concentration distribution. An 8 × 8 pixelated LaBr 3 (Ce) scintillator has been employed to improve the spatial resolution. In our previous report, the spatial resolution was improved by using the pixelated scintillator. However, the scintillation light produced in one pixel was sufficient to saturate the photon counts above 229 keV. Thus, a single peak was separated when the signals of all 64 channels were summed up. Many photon counts were eliminated to obtain the observed gamma-ray spectrum. In this study, an advanced 8 × 8 MPPC was employed, and the detector system had an energy resolution of 6.15% at 511 keV and spatial resolutions of 2.88 and 2.95 mm in the lateral and vertical directions, respectively, without eliminating any photon counts. In addition, the linearity of the photon counts of the 478 keV gamma rays and boron concentration was confirmed. • A prompt gamma-ray imaging detector was developed with an arrayed LaBr 3 (Ce) scintillator and a multi-pixel photon counter. • The energy resolution at 511 keV was 6.15% which was sufficient to discriminate between 478 and 511 keV gamma rays. • This detector system had the linearity between ADC channels and gamma-ray energies. • The linearity between B-10 concentration and the count rate of prompt gamma rays at 478 keV was confirmed. • The spatial resolution of this detector system was better than our previous detector system. [ABSTRACT FROM AUTHOR]

Positron annihilation lifetime (PAL) spectroscopy has long been considered as a powerful approach to characterize atomic-scale vacancy-type defects and supermicropores, which affect the macroscopic properties of materials. In standard PAL measurements, several million annihilation events are required to achieve accuracy. For a conventional PAL spectrometer which consists of two scintillation detectors and analytical electronics, the two detectors are usually perpendicularly positioned to diminish spectra distortions (caused by backscattering and pileup). The perpendicular placement of detectors leads to a counting rate of 100 – 300 counts/second (cps) while using a 30 μ Ci 22Na source (3.3 – 10 cps/ μ Ci). Consequently, collecting one PAL spectrum with total counts of one million takes several hours. The long time limits its potential to observe changes in the microstructure. To increase the counting rate of PAL measurements, we propose a novel multi-detector PAL spectrometer, which includes three or four detectors, a digital oscilloscope, and an algorithm for any detector to record both start and stop signals. The spectrometer achieves a high counting rate of around 2144 cps (71.5 cps/ μ Ci) with four detectors, which is about ten times that of a conventional one with two detectors perpendicularly positioned. This work enables us to perform in-situ PAL measurements to disclose the minute-scale evolution of microstructure more precisely during fast physical and chemical processes in the future. • A better spectrum unfolding accuracy can be achieved with a larger total count. • The scintillator size and geometry was optimized using Geant4. • A reversible start/stop data acquisition algorithm was developed to double the counting rate. • The novel spectrometer is highly extendable to 3, 4 and more detectors. • The counting rate of ten times higher than the conventional spectrometer was obtained. [ABSTRACT FROM AUTHOR]

An entrance window surrounded phoswich design of GAGG:Ce/CsI:Tl has been implemented for a low-background and Compton-suppressed detector. Not as the common phoswich detector does, the GAGG:Ce scintillator with the well-type CsI:Tl scintillator entrance window surrounded makes the efficient large-angle Compton suppression. This design also makes results measured by the phoswich detector have no degradation compared with the single GAGG:Ce detector. The Compton continuum and other backgrounds are reduced by identifying the gamma-ray energy depositions in different scintillators using the real-time rise time discrimination (RTD) method. The background rate is suppressed approximately 74%. The peak-to-total (P/T) ratio at 137Cs and 60Co point sources are 0.769 and 0.561, respectively. The Compton suppression is highly efficient at all the energy range of Compton continuums. The reduction of the Compton continuum and other backgrounds and the improvement of the P/T ratio will greatly expand the application range of the GAGG:Ce detector in low-intensity measurements. [ABSTRACT FROM AUTHOR]

The SBN program at Fermilab aims to measure ν μ → ν e neutrino oscillations at ∼ 1 km/GeV, resulting from the existence of a sterile neutrino, namely a fourth neutrino mass eigenstate at 1 eV that does not interact weakly but participate at the oscillation phenomenon with the three standard neutrinos. The SBN Far Detector, ICARUS T600, was run at LNGS Lab from 2010 to 2013 as the first and largest LArTPC ever operated. At Fermilab ICARUS is at the surface and therefore a Cosmic Ray Tagger system is necessary in order to reject the cosmic ray background. [ABSTRACT FROM AUTHOR]

Detectors in Positron Emission Tomography (PET) scanners are usually arranged in rings with the specimen lying along the axial direction. This distribution, however, does not maximize the geometrical sensitivity unless the axial extent becomes much longer than the axial Field of View (FOV), a very costly solution. The optimal geometry for a PET scanner is a sphere with the specimen located at the center. The state of the art of scintillator crystals and detectors for γ -rays does not facilitate smooth spherical geometry design. In this work we propose a PET scanner of 4 π steradian coverage for preclinical imaging as a proof of concept. As a first approximation to the ideal spherical topology, the scanner is shaped as an icosahedron. Furthermore we also present the new custom-tailored hexagonal Silicon Photomultiplier (SiPM) and a monolithic laser-engraved LYSO scintillator crystal that tiles the twenty scanner faces. Preliminary results of the scanner performance based on simulations point to enhanced sensitivity. Initial results on the characterization of the hexagonal photodetector by collection of pulses from a 22Na point source show similar performance as conventional square pixels with the benefit of the increased sensitivity and resolution. [ABSTRACT FROM AUTHOR]

High light yield scintillation materials on the base of lanthanide ions were demonstrated to be a multipurpose scintillation materials. They are widely used to detect γ –quanta and now become prospective to detect neutrons as well. Neutrons were detected through several distinct low energy γ –quanta peaks, generated by lanthanide nuclei in the materials under neutrons. Among three crystalline scintillators, namely lutetium oxy-orthosilicate, lanthanum bromide and gadolinium–aluminum–gallium garnet, the Gd 3 Al 2 Ga 3 O 12 :Ce (GAGG) scintillator showed the best performance and sensitivity due to the low internal background radioactivity and good cross section of neutron capture by natural mixture of the matrix host-creating Gd ions. The material fits the requirements for neutron detector properties — high Gd content and high scintillation light yield, stopping power and reasonable energy resolution for γ -quanta. These findings create prospects to construct compact multipurpose detectors for space and other application. [ABSTRACT FROM AUTHOR]

Abstract We investigate the performance of Fourier-based neutron/gamma Pulse Shape Discrimination (PSD) algorithms applied to plastic scintillators that are coupled to silicon photomultipliers (SiPM). The detector acquired data from a mixed fast neutron and gamma field which was emitted from an AmBe source. Pulses produced from the detector were fully digitised for off-line analysis with the algorithms. We describe the performance of two Fourier-based PSD algorithms, Fourier Gradient Analysis (FGA) and Fourier Area Analysis (FAA), and compare their performance to the Charge Comparison Method (CCM). To compare the algorithms' PSD performance the figure of merit (FoM) was calculated at various energies for each of the algorithms. The CCM analysed the pulses in the time domain whereas the other two algorithms processed the pulses within the frequency domain. Moreover, the detector was tested with different acquisition record lengths, in order to determine any impact on algorithm performance. It was determined that the FAA algorithm provided the best overall performance achieving a FoM of 1.57(1) at 1 MeV ee with a 1.6 µs record length. Furthermore, the detector was tested using different load resistors which allowed the decay time of the pulses to be optimised. The influence of SiPM pulse decay time on the performance of the PSD algorithms is also presented. [ABSTRACT FROM AUTHOR]

Multiplexing of radiation detectors reduces the number of readout channels, which in turn reduces the number of digitizer input channels for data acquisition. We recently demonstrated frequency domain multiplexing (FDM) of pulse mode radiation detectors using a resonator that converts the detector signal into a damped sinusoid by convolution. The detectors were given unique "tags" by the oscillation frequency of each resonator. The charge collected and the time-of-arrival of the detector pulse were estimated from the corresponding resonator output in the frequency domain. In this paper, we demonstrate a new method to recover the detector pulse from the damped sinusoidal output by deconvolution. Deconvolution converts the frequency-encoded detector signal back to the original detector pulse. We have developed a new prototype FDM system to multiplex organic scintillators based on convolution and deconvolution. Using the new prototype, the charge collected under the anode pulse can be estimated from the recovered pulse with an uncertainty of about 4.4 keVee (keV electron equivalent). The time-of-arrival can be estimated from the recovered pulse with an uncertainty of about 102 ps. We also used a CeBr 3 inorganic scintillator to measure the Cs-137 gamma spectrum using the recovered pulses and found a standard deviation of 13.8 keV at 662 keV compared to a standard deviation of 13.5 keV when the original pulses were used. Coincidence measurements with Na-22 using the deconvolved pulses resulted in a timing uncertainty of 617 ps compared to an uncertainty of 603 ps using the original pulses. Pulse shape discrimination was also performed using Cf-252 source and EJ-309 organic scintillator pulses recovered by deconvolution. A figure of merit value of 1.08 was observed when the recovered pulses were used compared to 1.2 for the original pulses. [ABSTRACT FROM AUTHOR]

The response of a position-sensitive Li-glass scintillator detector to α -particles from a collimated 241Am source scanned across the face of the detector has been measured. Scintillation light was read out by an 8 × 8 pixel multi-anode photomultiplier and the signal amplitude for each pixel has been recorded for every position on a scan. The pixel signal is strongly dependent on position and in general several pixels will register a signal (a hit) above a given threshold. The effect of this threshold on hit multiplicity is studied, with a view to optimize the single-hit efficiency of the detector. [ABSTRACT FROM AUTHOR]

Abstract The External Target Facility (ETF) has been constructed for reaction studies with high-energy secondary beams of several hundred MeV/u. The charged fragment detector system of ETF consists of a dipole magnet, tracking drift chambers, ionization chambers and plastic scintillators for particle identification (PID) via B ρ - Δ E-TOF method. The system is now ready for physics experiments. Before physics runs, it has been tested using 280 MeV/u 18O primary beam as well as the secondary beams produced by projectile fragmentation. The system used as a magnetic spectrometer has exhibited satisfying PID capability in identifying fragments ranging from nitrogen to beryllium. [ABSTRACT FROM AUTHOR]

Abstract The design, simulation, fabrication, calibration, and performance of the GlueX Start Counter detector are described. The Start Counter was designed to operate at integrated rates of up to 9 MHz with a timing resolution in the range of 500 to 825 ps (FWHM). The Start Counter provides excellent solid angle coverage, a high degree of segmentation for background rejection, and can be utilized in the level 1 trigger for the experiment. It consists of a cylindrical array of 30 thin scintillators with pointed ends that bend towards the beam line at the downstream end. Magnetic field insensitive silicon photomultiplier detectors were used as the light sensors. [ABSTRACT FROM AUTHOR]

Abstract We describe the design, fabrication, and performance of an energy analyzing detector package for cold neutron spectrometers at the NIST Center for Neutron Research (NCNR). The detector package consists of arrays of highly oriented pyrolytic graphite crystals set at takeoff angles corresponding to different neutron energies. Neutrons incident down the array will be selected out by the appropriate crystal and directed onto an associated neutron detector. The arrays are capable of binning neutrons into one of 54 bins over an energy range of 2.29 meV to 5.11 meV. We describe theory of operation, the development of a highly efficient ultrathin neutron sensor, and the development of the arrays themselves. We present preliminary results for this detector array along with a mature design of the scintillator neutron detector. We also present enhancements we are pursuing prior to deployment of this technology. [ABSTRACT FROM AUTHOR]

Abstract A new sensor for alpha particles based on plastic scintillators immersed in water was demonstrated to provide a viable solution for real-time detection of radioactive contaminants in water. It is obtained by stacking an array of plastic modules composed by a thin layer of Ag-doped zinc sulphide, ZnS(Ag), deposited on a plastic scintillator foil. Alpha particles are detected in the ZnS(Ag) layer, whereas beta are detected inside the plastic substrate. One still unexplored aspect of this novel detection technology is how the long-term contact with water affects the detector performance. To protect its surface from water-induced damages, we identified a coating protocol based on a poly(methyl-methacrylate) film deposited by spraying on the ZnS(Ag) active layer of the scintillator. The ageing process of the scintillator was carried out by using suitable aqueous solutions and the effect on the sensing layer was monitored by measuring its wettability and surface morphology. The performance of the coated scintillator was tested by measuring the efficiency with alpha radioactive sources. Highlights • Chemical analysis of plastic scintillators for alpha particle detection. • Coating protocol of plastic scintillators surfaces. • Wetting characterization of coated plastic scintillators. • Validation of the coating protocol after ageing process of the scintillators. [ABSTRACT FROM AUTHOR]

Abstract We have developed a new setup to measure prompt fission γ -ray spectra in neutron induced fission up to energies sufficient to reveal the structure associated with giant dipole resonances of fission fragments. The setup consists of multi-wire proportional counters, to detect both fission fragments in coincidence, and two large volume (101.6 mm in diameter and 127.0 mm in length) LaBr 3 (Ce) scintillators, to measure the γ rays. The setup was used to obtain the prompt fission γ -ray spectrum for thermal neutron induced fission of 235U at the PF1B cold-neutron beam facility of the Institut Laue-Langevin, Grenoble, France. We have successfully measured the γ -ray spectrum up to energies of about 20 MeV, what extends the currently known γ -ray spectrum limit to higher energies by approximately a factor of two. [ABSTRACT FROM AUTHOR]

Abstract The elpasolite crystal CLLB is proposed to detect both γ -ray and thermal neutron events with the ability to distinguish them by pulse shape discrimination (PSD) method. Pulse shapes of γ -ray, alpha particle, thermal and fast neutron events were measured and determined that PSD can be performed to separate γ -ray from alpha and thermal neutron events with a Figure of Merit (FoM) 1.23. The γ -ray non-proportional response is less than 2% in the energy region of 59.6 keV–4438 keV. Fast neutron responses for CLLB scintillator were investigated and analyzed using deuterium tritium (DT) reaction neutrons. The activity of 511 keV γ -ray emitted by 78Br and 80Br can reaches up to ∼ 0.709 Bq ⋅ n−1, some high-energy events at 15 MeVee – 18 MeVee were found that generated according to the reaction 6Li(n, T)4He. [ABSTRACT FROM AUTHOR]

Abstract We developed and characterized a new type (designated ZEBRA) of multi-layer composite heavy-oxide scintillatordetectors for fast neutron detection for homeland security and nuclear safeguards applications. In this heterogeneous detector medium, composite layers comprised of micro-granules of heavy-oxide scintillators (ZWO, CWO, PWO, BGO, GSO(Ce), GOS(Ce) and others) dispersed in transparent plastic are alternated with layers of clear plastic that serve as scintillation light guides and as a neutron moderator material. The physical peculiarities of the neutron interactions and the principal mechanisms of fast neutron registration in these detectors are discussed in detail. The fast neutron intrinsic detection efficiencies and sensitivities of ZEBRA-detectors based on BGO, ZWO and GSO(Ce) composite scintillators in response to neutrons from 239Pu–Be and 252Cf sources were measured. These detectors had cross-sectional areas ranging from 16 to 100 cm2. The sensitivities of such detectors of size 100 × 100 × 41 mm3 were found to be 40–51 cps/(nps × cm−2), a level that is comparable to the sensitivity of a typical 3He counter of 1600 cm2 area. The intrinsic efficiencies and sensitivities of the ZEBRA-detectors also compare favorably with those of fast neutron detectors based on large-size heavy-oxide single crystals, but the multi-layer composite ZEBRA structures are much less expensive and can be easily manufactured in much larger dimensions. This work represents a significant advance from earlier single-crystal detector types as part of our effort to explore alternatives and improvements to conventional 3He counters. [ABSTRACT FROM AUTHOR]

Abstract The pixelated scintillation screen as an important component of the X-ray imaging detector effectively solves the issue of the lateral spreading of scintillation light and improves the spatial resolution of X-ray imaging. In this work, the hexagonal as well as square arranged pixelated CsI scintillation screens based on the silicon pore templates with pore pitch about 4 μ m and diameter about 3 μ m were fabricated by vacuum melting injection method. The morphology, crystallinity, X-ray excited optical luminescence and X-ray imaging performance of the screens were investigated. The results show that the CsI scintillator was filled into the silicon pore templates uniformly and compactly without microbubbles even if the depth of the filled CsI microcolumns reaches 100 μ m. The pixelated scintillation screen exhibits good CsI crystallinity with (110) preferred orientation. The intensity of X-ray excited optical luminescence of the hexagonal arranged pixelated CsI scintillation screen increases by 14.3% compared with that of the square arranged screen with same thickness. Furthermore, the intensity of the pixelated CsI screen with 100 μ m thickness is 34.1% higher than that of the screen with 40 μ m thickness. The spatial resolution of the X-ray imaging system with the hexagonal arranged pixelated CsI scintillation screen is about 115 lp/mm and not sensitive to the screen thickness, which is 11.5% higher than that with the square arranged screen. The detective quantum efficiency of the system with the hexagonal arranged pixelated CsI scintillation screen appears relatively higher than that with the square arranged screen with same thickness and increases with the thickness of the screen. This means the X-ray imaging performance of the hexagonal arranged pixelated CsI scintillation screen is better than that of the square array arranged screen. Highlights • The hexagonal arranged pixelated CsI scintillation screens without microbubbles were successfully fabricated by vacuum melting injection method. • The spatial resolution of the X-ray imaging system with the hexagonal arranged pixelated CsI scintillation screen is about 115 lp/mm. • The intensity of X-ray excited luminescence of the hexagonal arranged pixelated CsI scintillation screen increases by 14.3% compared with the same thickness square arranged screen. [ABSTRACT FROM AUTHOR]

We have combined two low-threshold detector technologies to develop a large-mass, low-threshold detector system that simultaneously measures the athermal phonons in a sapphire detector while an adjacent silicon high-voltage detector detects the scintillation light from the sapphire detector. This detector system could provide event-by-event discrimination between electron and nuclear events due to the difference in their scintillation light yield. While such systems with simultaneous phonon and light detection have been demonstrated earlier with smaller detectors, our system is designed to provide a large detector mass with high amplification for the limited scintillation light. Future work will focus on at least an order of magnitude improvement in the light collection efficiency by having a highly reflective detector housing and custom phonon mask design to maximize light collection by the silicon high-voltage detector. [ABSTRACT FROM AUTHOR]

A highly segmented muon spin rotation/relaxation/resonance (μ SR) spectrometer with over 2500 channels has been proposed in the construction of Phase II of the China Spallation Neutron Source (CSNS). Plastic scintillators are chosen as the detector material due to their high sensitivity to charged particles and good flexibility to various geometries. Gamma-ray sources are commonly used to calibrate the light yield of plastic scintillators. Accordingly, a derivative method has been developed to efficiently locate the Compton edge in gamma-ray spectra. In this method, the minimum and width of the derivative data are regarded as the position of the Compton edge and an estimation of energy resolution, respectively. Both experiments and simulations demonstrate the good reliability of this method for Compton edge positioning and energy resolution characterization. The derived Compton edge shows a systematic shift to the right of its real location. The relative shift is proportional to the energy resolution with a factor of ∼ 0.13. The assumed energy resolution should be corrected by a factor of ∼ 1.19 which is confirmed by inorganic scintillator measurements. In the measurement of plastic scintillators, the assumed Compton edge and energy resolution can well reproduce the energy response spectra for different types of gamma-ray sources. [ABSTRACT FROM AUTHOR]

Organic plastic scintillators are largely exploited for fast timing detectors thanks to their short scintillation time with respect to inorganic crystals. Plastic scintillators are cheap to produce, light and easy to manipulate (any standard mechanical workshop can handle the cutting, polishing, etc.). Nowadays, fastest plastic scintillators available on the market are EJ-232 (Eljen Technology) and BC-422 (Saint Gobain) with a rise time of 350 p s , a decay time of 1. 6 n s and a pulse width of 1. 3 n s. Foreseen the performance improvement of timing detectors based on plastic scintillators, the development of faster scintillators can give a crucial contribution. TOPS is a project focused on the development of a new class of organic scintillators producing several liquid and solid samples. Comparing the light output and the timing properties of the samples exploiting minimum ionising particles, a selection of the highly performing TOPS scintillators has been investigated and characterised. The performance achieved with TOPS samples are extremely promising: a time resolution improvement from 10 up to 35% with respect to the EJ-232 has been demonstrated. In addition, an increase of light output has been obtained for all samples with a consequent potential improvement in energy resolution measurements of a factor up to 35%. [ABSTRACT FROM AUTHOR]