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At least 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Gallium oxide semiconductor-based large volume ultrafast radiation hard spectroscopic scintillators

We report on the development of the first-ever inorganic radiation-hard moisture-insensitive large volume spectroscopic semiconductor-based scintillator with less than 2 ns decay time and light yields as high as 8000 ph/MeV. Despite extensive research into scintillator materials, the quest for an ideal scintillator combining ultrafast decay times (akin to BaF 2 and Yb-doped scintillators such as Lu 2 O 3 :Yb), high light yields (exceeding 2000 photons per MeV), spectroscopic capabilities, and exceptional radiation hardness remain unfulfilled. In this study, we demonstrate and report for the first time the viability of large-volume (up to 20 mm thickness) gallium oxide (β-Ga 2 O 3 ) semiconductor-based scintillators for applications requiring these properties. These β-Ga 2 O 3 scintillators were grown using the fast turnaround (~2 days) crucible-free optical float zone (FZ) technique. The high light yield and ultrafast decay time of these high-purity n-type semiconductors with free carrier concentration of 6 × 10 17 cm –3 are attributed to native defects, specifically oxygen vacancies (V O ) and gallium–oxygen vacancy pairs (V Ga –V O ), generated during optimized FZ growth. The ultrafast decay, along with high light yield, enables excellent timing resolution and high count rate detection for applications like time-of-flight positron emission tomography, physics experiments, and nuclear safety. The radiation hardness of these devices has been documented in a separate publication.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Distance dependent quenching and gamma-ray spectroscopy in tin-loaded polystyrene scintillators

In this study, we report the synthesis and inclusion of rationally designed organotin compounds in polystyrene matrices as a route towards plastic scintillators capable of gamma-ray spectroscopy. Tin loading ratios of up to 15% w/w have been incorporated, resulting in photopeak energy resolution values as low as 10.9% for 662 keV gamma-rays. Scintillator constituents were selected based upon a previously reported distance-dependent quenching mechanism. Data obtained using UV-Vis and photoluminescence measurements are consistent with this phenomenon and are correlated with the steric and electronic properties of the respective organotin complexes. We also report fast scintillation decay behavior that is comparable to the quenched scintillators 0.5% trans-stilbene doped bibenzyl and the commercial plastic scintillator BC-422Q-1%. These observations are discussed in the context of practical considerations such as optical transparency, ease-of-preparation/scale-up, and total scintillator cost.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2020

Low Level Calibration of Liquid Scintillation Counting

Liquid Scintillation Counting (LSC) is an analytical laboratory method that quantifies the concentrations of alpha and beta emitting isotopes. The LSC method can be utilized for the detection of tritium, both environmentally and at nuclear facilities. Most LSC samples are aqueous-based and prepared as a radioactive sample dissolved or suspended in a high efficiency scintillation cocktail that converts radioactive energy into light pulses. When placed in counting vials, the liquid scintillation cocktail allows for optical coupling in which energy is released from the samples radioactive decay, and transferred to the scintillator. That energy is then absorbed to produce excited electrons that fall back to their ground-state and emit a pulse of light that is detected by the liquid scintillation analyzers photomultiplier tubes. Quench is a signal attenuation due to physical, chemical, or color interferences. To compensate for quench, quench standards of a known concentration are implemented at increasing increments of quench per vial to create a quench curve. Quench standards can be purchased pre-made or customized from the manufacturer, however, there are several issues that arise from purchasing the pre-made quench standards. The main issues with ordering pre-made quench standards is that they use higher count values, between 30,000 and 250,000 disintegrations per minute (dpm) of tritium per vial and only come in glass vials. Using higher counting standards in glass vials makes it hard to see lower concentrations in plastic vials. Additionally, when using higher energy standards the accuracy of the calibration readings tend to be lower. On the other hand, making a set of quench standards in-house allows for the customization of the dpm concentration to roughly 1,500-3,000 and preparation in plastic vials. This allows for lower activity readings that results in closer precision of the samples' true concentration. Technical Objectives: Create a quench curve and calibrate the LSA for tritium. Verify the calibration of the quench curve prior to cross sample runs. Check calibration against Quality Control (QC) reference value. Conclusion: a tritium quench curve calibration was performed using a scintillation cocktail with ultima gold (AB and AB/F), acetone (only with AB), and water (only with AB/F). By performing the tritium quench curve calibration, the counting efficiency was correlated to various levels of quench. Calibration checks with quality control standards were also performed to verify that the calibration was correct. The observed results provided acceptable values that matched the quality control standard reference values with an acceptable uncertainty. The next step will be fine tuning and cross comparison checks with legacy instrumentation.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2014

Neutron response characterization for an EJ299-33 plastic scintillation detector

Organic scintillation detectors have shown promise as neutron detectors for characterizing special nuclear materials in various arms-control and homeland security applications. Recent advances have yielded a new plastic scintillator - EJ299-33 - with pulse-shape-discrimination (PSD) capability. Plastic scintillators would have a much expanded range of deployment relative to liquids and crystals. Here in this paper, we present a full characterization of pulse height response to fission-energy neutrons for an EJ299-33 detector with 7.62-by-7.62-cm cylindrical active volume, and compare with an EJ309 liquid scintillator in the same assembly. Scintillation light output relations, energy resolutions, and response matrices are presented for both detectors. A Continuous spectrum neutron source, obtained via the bombardment of 27 Al with 7.44-MeV deuterons at the Edwards Accelerator Facility at Ohio University, was used for the measurement. A new procedure for evaluating and comparing PSD performance is presented which accounts for the effect of the light output relation on the ability to detect low energy neutrons. The EJ299-33 is shown to have considerable deficit in matrix condition, and in PSD figure of merit when compared to EJ309, especially when neutron energy is taken into account. Furthermore the EJ299 is likely to bring a modest PSD capability into a array of held applications that are not accessible to liquids or crystals.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

Evaluation of polyvinyl toluene scintillators for fast neutron imaging

We evaluated here polyvinyl toluene (PVT) scintillators fabricated with different emitting dopants and scintillator optical configurations for fast neutron imaging. A neutron imaging apparatus was constructed to study scintillators under MeV neutron exposure. PVT with 2% Xylyl Flrpic emitter was identified as the brightest. The addition of a black backing to the scintillator, compared with a specular reflector film backing, improved the resolution of the neutron image obtained with the PVT scintillator by about 2 ×. It is concluded that a PVT imaging screen with 2% Xylyl Flrpic, configured with a black backing, provides the best quality fast neutron image of the scintillators tested.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Influence of fluorescent dopants on the vat photopolymerization of acrylate-based plastic scintillators for application in neutron/gamma pulse shape discrimination

Plastic scintillators, a class of solid-state materials used for radiation detection, were additively manufactured with vat photopolymerization. The photopolymer resins consisted of a primary dopant and a secondary dopant dissolved in a bisphenol A ethoxylate diacrylate-based matrix. The absorptive dopants significantly influence important print parameters, for example, secondary dopants decrease the light penetration depth by a factor > 12×. The primary dopant 2,5-diphenyloxazole had minimal impact on the printing process even when loaded at 25 % by mass of the resin. Working curve measurements, which relate energy dose to cure depth, were performed as a function of feature size to further assess the influence of dopants. Photopatterns smaller than 150 µm width had apparent increases in critical energy dose compared to larger photopatterns, while all resins maintained printed features in line gratings with 50 µm of separation. Printed scintillator monoliths were compared to scintillators cast by traditional molding, demonstrating that the layer-by-layer printing process does not decrease scintillation response. In conclusion, a maximum light output of 31 % of a benchmark plastic scintillator (EJ-200) and successful pulse shape discrimination were achieved with 20 % by mass 2,5-diphenyloxazole as the primary dopant and 0.1 % by mass 9,9-dimethyl-2,7-distyrylfluorene as the secondary dopant in printed scintillator samples.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Further Investigations of the Effect of Replacing Lithium by Sodium on Lithium Silicate Scintillating Glass Efficiency

Ce3+ doped lithium (6Li) silicate glasses are thermal neutron detectors. Prior work showed that when sodium (Na) is substituted for Li the scintillation efficiency, under beta particle stimulation, increased and then decreased as the sodium (Na) content was increased [1]. When all the 6Li was replaced by Na no scintillation was observed. Raman spectra, acquired using a visible excitation source provided no evidence of anomalous behavior. SEM microscopy did show some phase separation, but there was no obvious correlation with the scintillation efficiency. We have reexamined these glass samples using deep UV Raman excitation which reduces fluorescence interference. The newly acquired spectra show evidence of phase separation in the glasses. Specifically we see a peak at 800 cm-1 Raman shift which can be assigned to a vitreous silica moiety that results from phase separation. There is a strong correlation between this peak's area, the scintillation efficiency, and the Na content. The observed trend suggests that phase separation enhances scintillation and addition of Na reduces the amount of phase separation. We also see evidence of at least two defect structures that can be tentatively assigned to a three-membered ring structure and an oxygen vacancy. The latter is fairly strongly correlated with enhanced scintillation efficiency.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Photoluminescence, photoacoustic, and scintillation properties of Te4+-doped Cs2HfCl6 crystals

Highlights: • Cs{sub 2}HfCl{sub 6}:Te{sup 4+} crystals were grown using the vertical Bridgman–Stockbarger method. • The PL, PA, and scintillation properties of the crystals were characterized. • An inverse correlation between scintillation LY and PA intensity was confirmed. - Abstract: Photoluminescence, photoacoustic, and scintillation properties are reported for 1.0, 3.0, 5.0, and 10 mol% Te{sup 4+}-doped Cs{sub 2}HfCl{sub 6} crystals grown using the vertical Bridgman–Stockbarger method. The UV − VIS light excited emission spectra showed an emission band peaking at 575 nm which can be ascribed to transitions from the {sup 3}T{sub 1u} and {sup 3}A{sub 1u} states to the {sup 1}A{sub 1g} state of Te{sup 4+} ions. Excitation spectra monitored at emission wavelength of 575 nm showed bands at 230–250 (charge transfer on a HfCl{sub 6}{sup 2−}), 275–300 ({sup 1}A{sub 1g} → {sup 3}T{sub 1u}), 300–340 ({sup 1}A{sub 1g} → {sup 3}T{sub 2u}, {sup 3}E{sub u}), and 360–460 nm ({sup 1}A{sub 1g} → {sup 1}T{sub 1u}). The X-ray induced scintillation spectra exhibited a yellow emission band at 575 nm, which is similar to the emission band for excitation by UV–VIS light. Scintillation light yields of the crystals were estimated to be approximately 11,700 (1.0 mol%), 13,100 (3.0 mol%), 9600 (5.0 mol%), and 9000 (10 mol%) photons/MeV, respectively. Scintillation light yield was inversely correlated with the PA intensity.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2017

Improved lithium iodide neutron scintillator with Eu 2+ activation: The elimination of Suzuki-Phase precipitates

Monovalent alkali halides such as NaI, CsI, and LiI are widely used as inorganic scintillators for radiation detection due to their light yield, the capability for the growth of large single crystals, relatively low cost, and other favorable characteristics. These materials are frequently activated through the addition of small amounts (e.g., a few hundred ppm) of elements such as thallium - or sodium in the case of CsI. The monovalent alkali halide scintillators can also be activated with low concentrations of Eu 2+ , however Eu activation has previously not been widely employed due to the non-uniform segregation of the divalent Eu dopant that leads to the formation of unwanted phases during Bridgman or other solidification crystal-growth methods. Specifically, for Eu concentrations near and above ~0.5%, Suzuki Phase precipitates form in the course of the melt-growth process, and these Suzuki Phase particles scatter the scintillation light. This adversely affects the scintillator performance via reduction in the optical transmission of the material, and depending on the crystal thickness and precipitated-particle concentration, this reduction can occur up to the point of opacity. Here we describe a post-growth process for the removal of Suzuki Phase precipitates from single crystals of the neutron scintillator LiI activated with Eu 2+ at concentrations up to and in excess of 3 wt.%, and we correlate the resulting neutron-detection performance with the thermal processing methods used to remove the Suzuki Phase particles. Furthermore, the resulting improved scintillator properties using increased Eu activator levels are applicable to neutron imaging and active interrogation systems, and pulse-height gamma-ray spectroscopy rather than pulse-shape discrimination can be used to discriminate between gamma ray and neutron interaction events.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

Tensile, flexural, and light output measurements of selected organic scintillators for evaluation of their potential as structural materials

In order to design structures, such as unmanned vehicle structures, out of plastic scintillator, e.g., for radionuclide searches, suitable materials must either be identified or developed. In searches utilizing unmanned vehicles, the absence of an additional detector attached to the vehicle body as a payload could enable the vehicle to travel faster, carry a longer lived battery, or carry other auxiliary equipment which may be useful for search and/or response. To this end, four mechanical characteristics of selected organic scintillators manufactured by Eljen technologies, Sandia Livermore, and Lawrence Livermore National Lab have been measured. Specifically, tensile and flexural tests have been performed to ASTM specifications on organic scintillators with polyvinyl toluene (PVT), polystyrene (PS), or crosslinked versions of these bases. In addition to these mechanical tests, light output testing was performed in order to quantify whether crosslinking or adding organometallic complexes affects light output in the particular scintillator compositions we measured. We found that the tested plastic scintillators have strengths that are comparable to common structural plastics. We also show that chemically modifying the polymer base can show improvements in the mechanical properties without being overly detrimental to the scintillator light output.

42 ENGINEERING↗
DOE OSTI2019

Investigations of degradation and encapsulation of plastic scintillator

Studies have revealed that plastic scintillators such as polyvinyl toluene and polystyrene can undergo environmentally related material damage (“fogging”) that adversely affects detection performance under certain conditions and histories. A significant decrease in sensitivity has been seen in some gamma-ray detectors as they age as a result of this damage. Performance degradation due to such damage is characterized by a signal change from the detector, which shifts to lower energy, and ultimately a reduction in the ability to detect gamma radiation. This degradation is due to the permeation of water into the plastic, which can then cause temporary fogging and permanent damage to the material. As an example, a 1-mm thick barrier of high-density polyethylene with an area of 1 m 2 would allow 5 g per year of water transmission at 100% relative humidity. Thus, significant amounts of water can penetrate plastics over time and provide the potential for damage to the plastic. Such damage to plastic scintillator can cause problems for radiation detection applications in uncontrolled environments. Mitigation approaches that have been proposed to prevent damage to plastic scintillator include encapsulation of the plastic scintillator to prevent water intrusion that leads to damage during cold cycles. It is concluded that an encapsulation material with a moisture vapor transmission rate on the order of 10 -4 g∙m -2 ∙d -1 or better is needed for protecting large pieces of plastic scintillator from fogging over years of use. This article presents information on testing of bare and encapsulated plastic scintillator samples and on diagnostic approaches to measure the nature and progression of the fogging condition. It is shown that several encapsulation approaches fail to prevent water intrusion, while a couple methods can successfully encapsulate plastic and prevent water from penetrating the plastic and producing fogging.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Performance evaluation of pulse shape discrimination capable organic scintillators for space applications

Scintillators with pulse-shape discrimination (PSD) capability are of great interest to many fields in the scientific community. The ability to discern a gamma ray from a neutron using PSD varies between different types of scintillator materials and dopants. Here a new generation of organic scintillator materials with PSD capability were studied to determine their radiation hardness to neutron and gamma-ray radiation. The PSD capability, average pulse shapes, and light output of four types of organic scintillator were characterized before and after neutron and gamma-ray irradiation. The main goal of this investigation is to study the effects of long-term irradiation that may be experienced in space applications on the light output and particle discriminating capabilities of each material. EJ-270, EJ-276, organic glass, and Stilbene were tested. Damage due to neutron irradiation (displacement damage) was not observed in any of the scintillators up to 2.56 x 10 11 n/cm 2 , except for Stilbene which showed a small (12%) decrease in light output. All scintillators presented some light output reduction after gamma-ray irradiation (total ionizing dose), with reductions of 17% (EJ-276 and OGS), 32% (EJ-270), and 42% (Stilbene) observed immediately after 100 kRad.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2026

A method for estimating light quenching in inorganic scintillator detectors for radioactive ion beam experiments

In recent experiments, inorganic scintillators have been used to study the decays of exotic nuclei, providing an alternative to silicon detectors and enabling measurements that were previously impossible. However, proper use of these materials requires us to understand and quantify the scintillation process, specifically in response to very heavy nuclei. Here, in this work, we show a simplified method based on the models of Birks (1951) and Meyer and Murray (1962) to parametrize the light output of inorganic scintillators in response to beams of energetic heavy ions over a broad range of energies. We test the accuracy of our parametrization approach by calculating light output and quenching factors for various ions and comparing them with experimental data from Lutetium Yttrium Orthosilicate (LYSO:Ce), a common inorganic scintillator. The Meyer–Murray model suggests that, for sufficiently heavy ions at high energies, the majority of the light output is associated with the creation of delta electrons, which are induced by the passage of the beam through the material. These delta electrons dramatically impact the response of detection systems when subject to ions with velocities typical of beams in modern fragmentation facilities. To illustrate this, we also present a qualitative estimate of the effects of delta rays on overall light output using the Birks–Meyer–Murray parametrization. The approach presented herein will serve as a basic framework for further, more rigorous studies of scintillator response to heavy ions. This work is a crucial first step in planning future experiments where energetic exotic nuclei are interacting with scintillator detectors.

Heavy ion↗
DOE OSTI2017

Plastic scintillators relative gamma-ray light yield measurement

Here we are investigating the inclusion of organotin compounds in polystyrene material to improve plastic scintillators full gamma-ray energy sensitivity with the ultimate goal of achieving spectroscopy. Accurate evaluation of the relative light yield from the newly developed scintillators is crucial to assess merits of compounds and chemical processes used in the scintillators development and assess the scintillation efficiencies of the newly produced scintillators. Full gamma-ray energy peak in the measured gamma-ray spectrum, resulting from total absorption of gamma-ray energy, would be ideal in assessing the relative light yield. However, the significant number of new samples we are producing for investigation lead us to the possibility of using the Compton edge as an alternate spectral feature that can be exploited for expeditious characterization of the relative light yield in plastic scintillators. In this study we present a spectra gain matching approach, using a spectrum rebinning, for accurate relative light yield measurement using the Compton edge.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Relative sensitivity of plastic scintillator: A comparative analysis with 60 Co gamma rays, deuterium–deuterium, and deuterium–tritium neutrons

A plastic scintillator has found extensive application in the realm of high-energy physics and national security science. Many applications in those fields often involve the simultaneous production of photons, neutrons, and charged particles, which makes the relative sensitivity information for these different radiation types important. In this study, we have adopted a multi-head detector comprised of a plastic scintillator and high gain phototubes, which provides a large dynamic range and linearity. A comparative study on the relative sensitivities of plastic scintillators was facilitated by adopting three distinct radiation calibration sources (i.e., 60 Co γ rays, DD neutrons, and DT neutrons). Neutrons from a DD source generate a comparable level of scintillation to gamma rays emitted by 60 Co (i.e., 60 Co-γ/DD-n = 0.92 ± 16%). DT neutrons induce ~3.5 times the scintillation observed with DD neutrons (i.e., DT-n/DD-n = 3.5 ± 28%). In addition, the Geant4 simulation granted us valuable insights into the relative sensitivity of the scintillator. This comparative study will provide a useful database for users in diverse applications.

47 OTHER INSTRUMENTATION↗
DOE OSTI2016

Metal-loaded organic scintillators for neutrino physics

Organic liquid scintillators are used in many neutrino physics experiments of the past and present. In particular for low energy neutrinos when realtime and energy information are required, liquid scintillators have several advantages compared to other technologies. In many cases the organic liquid needs to be loaded with metal to enhance the neutrino signal over background events. Several metal loaded scintillators of the past suffered from chemical and optical instabilities, limiting the performance of these neutrino detectors. Different ways of metal loading are described in the article with a focus on recent techniques providing metal loaded scintillators that can be used under stable conditions for many years even in ton scale experiments. Lastly, we review applications of metal loaded scintillators in neutrino experiments and compare the performance as well as the prospects of different scintillator types.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Measurements of attenuation and scattering properties of water-based liquid scintillator

Water-based liquid scintillator (WbLS) is a hybrid detector medium which has been proposed as a fill material for future large-volume rare event searches, including ν − detectors. This family of scintillating suspensions promises waterlike attenuation and scattering behavior, while offering scintillation light yield for sub-Cherenkov-threshold events. These features may allow for improved vertex and energy resolution, and concomitant improvements in background rejection and particle identification. While subscale measurements of light yield, timing and pulse-shape have been performed in several WbLS formulations, detailed measurements of the attenuation and scattering properties of WbLS remain a critical, unresolved step along the pathway to deployment. In pursuit of a better understanding of these parameters, a “long-arm” attenuation and scattering instrument has been developed at Lawrence Livermore National Laboratory, dubbed LASE (Livermore Attenuation and Scattering Experiment). Optical property measurements have been performed using LASE in DI water, Gd-water, WbLS and Gd-WbLS. Measurements of the optical properties of WbLS (1% LAB-PPO scintillator) provided by Brookhaven National Laboratory demonstrate an attenuation minimum of 4.87 × 10 − 4 ± 1.42 × 10 − 4 cm − 1 at 450 nm, while Gd-loaded WbLS (1% LAB-PPO scintillator, 0.1% Gd) demonstrated a minimum attenuation coefficient of 4.77 × 10 − 4 ± 1.27 × 10 − 4 cm − 1 at the same wavelength. Measurements of scattering in WbLS show a scattering coefficient of 3.39 × 10 − 4 ± 1.98 × 10 − 5 cm − 1 at the 450 nm attenuation minimum, while Gd-WbLS has a scattering coefficient of 2.8 × 10 − 4 ± 1.63 × 10 − 5 cm − 1 at that wavelength. These scattering and attenuation coefficients are significantly larger than measured for DI water at similar wavelengths ( 8.8 × 10 − 5 cm − 1 ± 3.8 × 10 − 5 attenuation at 430 nm, 2.2 × 10 − 5 ± 1.28 × 10 − 6 cm − 1 scattering). Though the WbLS attenuation and scattering coefficients measured are lower than the corresponding values published for ultrapure oils and LAB-PPO liquid scintillator, the material tested attenuates significantly more than water across the blue and green portions of the visible spectrum. This attenuation is markedly stronger at wavelengths under 430 nm. Published by the American Physical Society 2025

47 OTHER INSTRUMENTATION↗
DOE OSTI2020

Neutron Response of the EJ-254 Boron-Loaded Plastic Scintillator

Organic scintillators doped with capture agents provide a detectable signal for neutrons over a broad energy range. This work characterizes the fast and slow neutron response of EJ-254, an organic plastic scintillator with 5 loading by weight. For fast neutrons, the primary mechanism for light generation in organic scintillators is n-p elastic scattering. To study the fast neutron response, the proton light yield of EJ-254 was measured at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory. Using a broad-spectrum neutron source and a double time-of-flight technique, the EJ-254 proton light yield was obtained over the energy range of approximately 270 keV to 4.5 MeV and determined to be in agreement with other plastic scintillators comprised of the same polymer base. To isolate the slow neutron response, an AmBe source with polyethylene moderator was made incident on the EJ-254 scintillator surrounded by an array of EJ-309 observation detectors. Events in the EJ-254 target coincident with the signature 477.6 keV γ ray (resulting from de-excitation of the residual 7Li nucleus following boron neutron capture) were identified. Pulse shape discrimination was used to evaluate the temporal differences in the response of EJ-254 scintillation signals arising from γ-ray and fast/slow neutron interactions. Clear separation between γ-ray and fast neutrons signals was not achieved and the neutron capture feature was observed to overlap both the γ-ray and fast neutron bands. Taking into account the electron light nonproportionality, the neutron capture light yield in EJ-254 was determined to be 89.4±1.1 keVee.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗