Inorganic Scintillation Crystals Research Articles

On the doping effects and structural defects in some classical inorganic scintillation crystals

On the doping effects and structural defects in some classical inorganic scintillation crystals

Module Tester for Positron Emission Tomography and Particle Physics

The combination of high-density, high-time-resolution inorganic scintillation crystals such as Lutetium Yttrium Oxyorthosilicate (LYSO), Yttrium Orthosilicate (YSO) and Bismuth Germanate (BGO) with Silicon Photomultiplier (SiPM) sensors is widely employed in medical imaging, particularly in Positron Emission Tomography (PET), as well as in modern particle physics detectors for precisely timing sub-detectors and calorimeters. During the assembly of each module, following individual component testing, the crystals and SiPMs are bonded together using optical glue and enclosed in a light-tight, temperature-controlled cooling box. After integration with the readout electronics, the bonding is initially tested. The final readout electronics typically comprise Application-Specific Integrated Circuits (ASICs) or low-power Analog-to-Digital Converters (ADCs) and amplifiers, designed not to heat up the temperature-sensitive SiPM sensors. However, these setups are not optimal for testing the optical bonding. Specific setups were developed to test the LYSO + SiPM modules that are already bonded but not enclosed in a box. Through large data collection, small deviations in bonding can be detected if the SiPMs and LYSOs have been thoroughly tested before our measurement. The Monte Carlo simulations we used to study how parameters—which are difficult to measure in the laboratory (LYSO absorption length, refractive index of the coating)—affect the final result. Our setups for particle physics and PET applications are already in use by research institutes and industrial partners.

Crystal Growth, Photoluminescence and Radioluminescence Properties of Ce3+-Doped Ba3Y(PO4)3 Crystal

Inorganic scintillation crystals have been widely used in applications of high-energy physics, nuclear medical imaging, industrial nondestructive inspection, etc. In this work, a single crystal Ba3Y(PO4)3 (BYP) with 1.0 at% Ce3+-doping concentration was first grown by the Czochralski method, and the electronic structure was calculated using first principles based on density functional theory. In addition, a series of Ce3+-doped BYP phosphors were synthesized, and the fluorescence emission under UV excitation was measured through low-temperature spectroscopy, containing double-peaked emission from 5d–4f transition and self-trapped exciton recombination. A comparison of the UV and X-ray-excited fluorescence spectra reveals the existence of oxygen vacancies as well as F+ centers in the crystal. The air annealing of the crystal effectively reduces the thermoluminescence defects but reduces the emission intensity under UV or X-ray excitation. The BYP:Ce crystal shows a fast decay lifetime of 15.5 ns, and the fast component is as short as 8 ns. The results show that the Ce3+-doped BYP crystal has potential as a kind of scintillator with fast decay properties.

Structural, photoluminescence and scintillation properties of Ce-doped Al(PO3)3–Sr(PO3)2–CsPO3 inorganic glass scintillators for gamma- and X-ray detection

Scintillators have been commercialized as radiation detectors in several practical applications. However, fabrication of commercial inorganic crystal scintillators is time-consuming and expensive. Herein, we report inorganic glass scintillators for gamma and X-ray detection based on phosphate glasses, with alkali and alkali earth metals in the host and Ce3+ ions as emission centers. Unlike inorganic crystals, inorganic glasses have industrial advantages owing to their low cost and ease of fabrication, which facilitate the large-scale production of scintillators. Previously studied inorganic glass scintillators for gamma and X-ray detection exhibited low light yields compared to inorganic crystal scintillators. In contrast, our glass exhibits a high light yield of 3200 photons/MeV. This light yield is higher than that of previously reported glasses, whose light yields are less than several hundred photons/MeV in most cases and approximately 2000 photons/MeV as the highest value. In addition, this glass has a relatively high density of 3.33 g/cm3 and a fast scintillation decay of approximately 30 ns, which is attributed to the 5d–4f transition of Ce3+ ions acting as emission centers. These properties are suitable for gamma and X-ray detection and this glass has the potential to expand the practical applications of inorganic glass scintillators.

Novel optical-guiding crystal scintillator composed of an Eu-doped SrI2 core and glass cladding

Scintillators are used not only as single crystals in radiation detection systems but also as arrays, columns, and fibers. In this study, a novel optical-guiding crystal scintillator (OCS) was fabricated using an Eu:SrI2 crystal as the core and borosilicate glass as the cladding. The OCS has an elongated shape and can be flexibly processed like an optical fiber. Furthermore, because inorganic scintillator crystals are used as the core, the OCS has high sensitivity to high-energy radiation, such as γ- and X-ray radiation, unlike plastic scintillators. In this study, by observing the cross section of the fabricated OCS, identifying the crystal structure, and investigating the radioluminescence spectrum under X-ray irradiation, OCS fabrication in accordance with the OCS design specifications was confirmed, and the SrI2 crystal structure and Eu2+ 5d–4f luminescence were maintained. The γ-ray responses, such as light yield and decay time, were also investigated.

Stokes Shift Engineered Mn:CdZnS/ZnS Nanocrystals as Reabsorption‐Free Nanoscintillators in High Loading Polymer Composites

AbstractPlastic scintillators are gaining attention as alternatives to inorganic scintillator crystals owing to their low fabrication cost, customable shape/size, and substantially lighter weight that make them suitable for various radiation detection technologies. These include scintillation panels for national security and industrial monitoring, radiation screens for medical diagnostics, and calorimeters for high energy physics. Because of their low density, plastic scintillators are typically doped with high atomic number (Z) sensitizers that enhance the interaction probability with ionizing radiation and excite molecular emitters. Although effective, such a two‐component design suffers from incomplete sensitization, intrinsically limited efficiency due to multiple radiative steps with non‐unity quantum yield, detrimental phase segregation effects and the fragility of organic emitters to ionizing radiation. In this work, an alternative single‐component scheme is proposed based on high‐Z reabsorption‐free CdZnS/ZnS semiconductor nanocrystals (NCs) doped with manganese embedded in a polyvinyltoluene (PVT) waveguide. Optical‐grade nanocomposites free from optical reabsorption of the scintillation light and with performance comparable to commercial products are obtained through a post‐synthesis resurfacing procedure that maximizes the compatibility between the NCs and PVT and preserves their optical properties upon curing.

Time structure of pencil beam scanning proton FLASH beams measured with scintillator detectors and compared with log files.

Key factors in FLASH treatments are the ultra-high dose rate (UHDR) and the time structure of the beam delivery. Measurement of the time structure in pencil beam scanning (PBS) proton FLASH treatments is challenging for many types of detectors since high temporal resolution is needed. In this study, a fast scintillator detector system was developed and used to measure the individual spot durations as well as the time when the beam moves between two positions (transition duration) during PBS proton FLASH and UHDR treatments. The spot durations were compared with machine log-file recordings. A detector system based on inorganic scintillating crystals was developed. The system consisted of four detector probes made of a sub-millimeter ZnSe:O crystal that was coupled via an optical fiber to an optical reader with 50kHz sampling rate. The detector system was used in two experiments, both performed with a PBS proton beam with 250MeV beam energy and 215nA requested nozzle beam current. The sampling rate enabled multiple measurements during each spot delivery and during the beam transition between spots. First, the detector was tested in a phantom experiment, where a total of 305 scan sequences were delivered to the four detectors. The number of spots delivered without beam interruption in a single scan sequence ranged from one to 35. The spot duration and transition duration were measured for each individual spot. Secondly, the detector system was used in vivo in preclinical experiments with FLASH irradiation of mouse legs placed in the entrance plateau of the beam. A single detector was placed 1cm downstream of the irradiated mouse leg. The mouse dose ranged from 30.5 to 44.2Gy and the field consisted of 35 spots. The spot durations as well as the mean dose rate (field dose divided by the measured field duration) for each mouse were determined using the detector and then compared with the corresponding log files. The phantom experiment showed that the logged total duration of an uninterrupted spot sequence was consistently shorter than the measured duration with a difference of -0.252ms (95% confidence interval: [-0.255, -0.249ms]). This corresponded to 0.05%-0.07% of the spot sequence duration in the mice experiments. For individual spots, the mean±1SD difference between logged and measured spot duration was -0.39±0.05ms for the first spot in a sequence, 0.13±0.04ms for the last spot in a sequence, and -0.0017±0.09ms for the intermediate spots in a sequence. The measured spot transition durations were 0.20±0.04ms (5.1mm horizontal steps) and 0.50±0.04ms (5.0mm vertical steps). For the mouse experiments, the mean dose rate calculated from the measured field duration was 84.1-92.5Gy/s. It agreed with log files with a root mean square difference of 0.02Gy/s. Fiber-coupled scintillator detectors were designed with sufficient temporal resolution to measure the spot and transition duration during PBS proton UHDR deliveries. Their small volume makes them feasible for in vivo use in preclinical FLASH studies. The logged spot durations were in excellent agreement with measurements but showed small systematic errors in the logged duration for the first and last spot in a sequence.

Scintillation in Low-Temperature Particle Detectors

Inorganic crystal scintillators play a crucial role in particle detection for various applications in fundamental physics and applied science. The use of such materials as scintillating bolometers, which operate at temperatures as low as 10 mK and detect both heat (phonon) and scintillation signals, significantly extends detectors performance compared to the conventional scintillation counters. In particular, such low-temperature devices offer a high energy resolution in a wide energy interval thanks to a phonon signal detection, while a simultaneous registration of scintillation emitted provides an efficient particle identification tool. This feature is of great importance for a background identification and rejection. Combined with a large variety of elements of interest, which can be embedded in crystal scintillators, scintillating bolometers represent powerful particle detectors for rare-event searches (e.g., rare alpha and beta decays, double-beta decay, dark matter particles, neutrino detection). Here, we review the features and results of low-temperature scintillation detection achieved over a 30-year history of developments of scintillating bolometers and their use in rare-event search experiments.

A Review of Inorganic Scintillation Crystals for Extreme Environments

In the past, the main research and use of scintillators in extreme environments were mainly limited to high energy physics and the well-logging industry, but their applications are now expanding to reactor monitoring systems, marine and space exploration, nuclear fusion, radiation therapy, etc. In this article, we review and summarize single-crystal inorganic scintillator candidates that can be applied to radiation detection in extreme environments. Crucial scintillation properties to consider for use in extreme environments are temperature dependence and radiation resistance, along with scintillators’ susceptibility to moisture and mechanical shock. Therefore, we report on performance change, with a focus on radiation resistance and temperature dependence, and the availability of inorganic scintillator for extreme environments—high radiation, temperature, humidity and vibration—according to their applications. In addition, theoretical explanations for temperature dependence and radiation resistance are also provided.

Geant4 ile İnorganik Kristal Sintilatörler için Enerji Çözünürlüğünün Reflektör Malzemesine Bağımlılığı Üzerine Çalışma

The scintillator has played a primary role as the ideal device for the detection and measurement of particles and radiation in modern physics. With the development of experimental physics, the demand for new improved scintillating materials for several types of applications has kept increasing. High efficiency, fast scintillation and good energy resolution are among the most desired specifications as to a good scintillator. Yet, a variety of scintillators can be preferred depending on the precise specifications of the application considered. If the case is that the detection of gamma rays and high-energy electrons or positrons, inorganic crystals are exceptionally suitable scintillator because highly intense light outputs and the strong stopping power enable these type of crystals to provide better energy resolution among all scintillators. In this study, a scintillation detector consisting of inorganic crystal scintillator material (NaI:Tl and CsI:Tl) was modeled with the help of Geant4 scientific toolkit to determine if the energy resolution of the inorganic crystal scintillator detector is dependent on crystalline size and reflector material. In each simulation, different sized crystal covered with a variety of reflector type was exposed to the same energy gamma radiation; the resulting energy spectrum was evaluated and compared to others obtained.

The Future Role of Inorganic Crystal Scintillators in Dark Matter Investigations

Crystal scintillators and in particular inorganic scintillators play an important role in the investigation of Dark Matter (DM) and other rare processes. The investigation of a DM signature, as the annual modulation, or the directionality technique requires the use of highly radiopure detectors able to explore the very low energy region maintaining a high stability of the running conditions. In this paper, the cases of NaI(Tl), ZnWO4 and SrI2(Eu) crystal scintillators are described in the framework of our activities at the Gran Sasso National Laboratory of the INFN. Their role, the obtained results in DM investigation, as well as their potential and perspectives for the future are reviewed.

Techniques for Background Identification in the Search for Rare Processes with Crystal Scintillators

In astroparticle, nuclear and subnuclear physics, low-counting experiments play an increasingly important role in the investigation of rare processes such as dark matter, double beta decay, some neutrino processes and low-background spectrometry. Extremely low-background features are more and more required to produce detectors and apparata of suitable sensitivity. Over time, a great deal of interest and attention in developing experimental techniques suitable to improve, verify and maintain the radiopurity of these detectors has arisen. In this paper, the characterization of inorganic crystal scintillators (such as, e.g., NaI(Tl), ZnWO4 and CdWO4) using α, β and γ radioactive sources and the main experimental techniques applied in the field to quantitatively identify the radioactive contaminants are highlighted; in particular, we focus on inorganic crystal scintillators, widely used in rare processes investigation, considering their applications at noncryogenic temperatures in the framework of the DAMA experiment activities at the Gran Sasso National Laboratory of the INFN (National Institute for Nuclear Physics, INFN).

A novel scintillation screen for achieving high-energy ray detection with fast and full-color emission

A novel CsPbX3 NCs@BaF2 scintillation screen is developed for fast and full-color emission under high-energy ray excitation. The light yield of the CsPbBr3 NCs@BaF2 can reach up to 6300 photons/MeV and its fast decay time component is about 11 ns.

Gamma scintillation spectrometer calibration using the method of mathematical modeling

The article describes a method for calibrating a gamma ray spectrometer using a three-dimensional simulation program for the transfer and registration of ionizing radiation. In the example of calibration of plane source counters (filter AFA-RMP20), this method allows one to determine the activity by using spectrometric equipment based on inorganic scintillation crystals. We proposed a method for parametric estimation of the identity of the calculated and experimental spectrum based on the Pearson agreement criterion. We then performed interlaboratory comparisons. The results demonstrate that the difference between measured values of the activity in the test samples of radionuclides using obtained calibration and values measured with a semiconductor based calibrated spectrometer do not exceed 20%.

Light yield of cold undoped CsI crystal down to 13 keV and the application of such crystals in neutrino detection

The light yield of an undoped CsI crystal at about 77 Kelvin was measured to be 33.5 , pm , 0.7 photo-electrons (PE) per keV electron-equivalent (keVee) in the energy range of [13, 60] keVee using X and gamma -rays from an ^{241}Am radioactive source. Based on this experimental result, the performance of 10 kg cryogenic inorganic scintillating crystals coupled to SiPM arrays to probe non-standard neutrino interactions through the detection of coherent elastic neutrino-nucleus scatterings at the spallation neutron source, Oak Ridge National Laboratory, was examined in detail.

Low background scintillators to investigate rare processes

Many developments, researches on innovative materials and purification techniques have offered a wide set of inorganic scintillators to investigate many processes; further developments are still in progress. In particular, efforts to realize very low background detectors have opened their effective application to the search of rare processes deep underground. Several cases will be outlined offering—to some extent—a discussion of several inorganic crystal scintillators' performances and their potentiality for the future.

Optical Properties of Continuous and Pixelated Scintillation Crystals

The optical photon distribution produced inside continuous and pixelated scintillation crystals by the absorption of a γ-ray have been studied with the photon transport program DETECT 2000. With this program the charge signals recorded by a multi-wired anode system, like the Position Sensitive PhotoMultiplier Tube (PSPMT) of a γ-Camera, are simulated. Based on the analytical parametrization which is fitted to experimental data, a new position reconstruction method for PSPMTs is proposed in this work. Planar images have been reconstructed with the new method and compared to the traditional charge center of gravity technique. Data are obtained from a small field, high resolution γ-Camera system with a multi- wired crossed anode using the R2486 (HAMAMATSU) PSPMT. Systematic studies for continuous and pixelated inorganic scintillation crystals of CsI(Tl) have been performed for different phantom geometries using small capillaries of 99mTc. The developed method seems to drastically improve the resolution of the reconstructed planar information, even when homogeneous crystals are used.

Study on Scintillation Properties of Several Non-fluoride Halides under Low Energy241 Am radiation

A few of halide inorganic scintillation crystals have been applied as radiation detection materials and are playing important roles in nuclear medicine, high energy physics, security inspection, petroleum logging and so on, but most of them are on the way of research and development. In this paper, a series of novel halide scintillation crystals, LaBr3(Ce), LaCl3(Ce), SrI2(Eu), Cs2LiYCl6(Ce) and NaI(Tl) were studied using low energy 241Am radioactive source. The effect of reflective film thickness on low-energy ray transmittance and light output of encapsulated scintillators was investigated, Teflon thickness of 0.48 mm as reflective film is best choice to obtain higher light collection and better radiation transmittance. Among all these crystals, LaBr3(Ce) crystal has excellent energy resolution above 25keV gamma ray radiation, 9.3% at 26.34 keV, 8.4% at 59.54 keV and2.6% at 661.66 keV. Only NaI (Tl) crystal works fine below 25 keV X-rays radiation, with energy resolution of 17.68% at 13.9 keV, 14.16% at 17.8 keV and 13.42% at 20.8 keV.

Core‐Shell Nanoparticle Probe Scintillation Proximity Assays for Biological Samples

To achieve the overall goal of sensitive and selective radioisotope detection in aqueous samples, we have developed a novel polystyrene‐core silica‐shell nanoparticle scintillator platform (nanoSPA). nanoSPA enabled separation‐free quantification of radiolabeled analytes in complex samples as demonstrated by scintillation proximity assays via protein‐tag, biotin, and antibody binding as well as by other methods such as chemical crosslinking and adsorption.β‐particle emitting radionuclides such as 3H, 33P, and 35S are useful molecular labels due to their small size but are challenging to detect and quantify with spatial and temporal resolution in biological samples due to their low energies (Emax ≤ 300 keV) and short penetration depths (≤ 0.6 mm). Activity measurements for these β‐emitters are usually made in milliliter volumes of liquid scintillation cocktail (LSC), a mixture of energy‐absorbing organic solvents, surfactants, and scintillant fluorophores, which is incompatible with living cells and dynamic biological measurements. Alternatively, solid polymer or inorganic crystals can be used, but the orientation of polymer sheets, the large size of polymer particles (> 2μm) and the high density of inorganic scintillators can result in inaccurate counting. nanoSPA avoids the toxicity of LSC as well as many of the limitations of polymer and inorganic crystal scintillators. The polystyrene acts as an absorber for energy from emitted β‐particles and is loaded with scintillant fluorophores to which the energy is transferred, leading to photon emission at visible wavelengths. The silica shell serves as a hydrophilic shield for the polystyrene core and facilitates functionalization with specific binding molecules for scintillation proximity assays. In this way, the short penetration depths of low‐energy β‐particles are used advantageously, as radiolabeled analytes that are not close enough to the nanoparticle surface (primarily bound to the surface during an assay) are less likely to be detected, resulting in low background signal. Selectivity was determined to be up to 30 times greater for bound 3H‐analytes over unbound 3H analytes when the labeled species was covalently bound to nanoSPA, 18 times greater for antibody functionalized nanoSPA, 8 times greater for biotin functionalized nanoSPA, and 4 times greater for ssDNA functionalized nanoSPA. We have also measured and monitored peptide phosphorylation with kinase and 33P ɣ ‐ ATP. nanoSPA not only facilitates measurement of radiolabeled analytes in bulk aqueous solutions, but due to the small diameter and the protection of the hydrophobic polymer core by the silica shell, nanoSPA particles could potentially be used as cellular or intracellular imaging probes.Support or Funding InformationThis work was supported in part by the National Science Foundation under grant number 1807343, the National Institutes of Health via the National Institute of Biomedical Imaging and Bioengineering under grant number R21EB019133 and the National Institute of General Medical Sciences under grant number 1R01GM116946.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Moh’s hardness Scale and micro vicker’s hardness study of bgo and lyso inorganic scintillators

BGO and LYSO inorganic scintillation crystals were chosen in this paper for density and hardness properties investigation. Moh’s hardness scale was determined by scratching test which of the standard minerals. The micro vicker’s hardness was measured with a diamond indenter and the test load was used at 0.1 kgf. The results show that, the moh’s hardness scale of LYSO crystal are higher than BGO crystal which correspond with micro vicker’s hardness values. The density of scintillation crystals were measured and found to be 7.1 g/cm3 for BGO crystal and 7.15 g/cm3 for LYSO crystal.