Inorganic Scintillation Materials Research Articles

An investigation of some ionizing radiation interaction parameters in selected composite scintillation materials

In this study, the interaction parameters of neutrons, charge particles and gamma rays in seven inorganic scintillation materials with densities ranged from 3.86 to 8.30 g/cm3 were theoretically examined. SRIM Monte Carlo software was used to determine the range of H + , H e + + , A u + and O − − ions in the energy range (0.01–20) MeV, Phy-X/PSD while Py-MLBUF computer programs were used to estimate gamma radiation interaction parameters in the energy range (0.02–15) MeV. The electron total stopping power and range values at energies ranging from 0.01 to 1000 MeV were calculated using the ESTAR NIST program. The fast neutron removal cross-section (FNRCS) and the macroscopic effective removal cross-section (MRCS) were calculated using the Phy-X/PSD and MRCS tools, respectively. The outcomes of this research showed that the range of H + , H e + + , A u + and O − − ions increased with decreasing sample density but decreased with increasing projectile energies; the largest range of H + is 2090 µm in the lowest density S1 sample, while the range of A u + is 5.16 µm in the same sample. The denser sample S7 had the highest stopping power and the lowest range at higher electron energies. The S1 sample had the highest calculated HVL value of 5.403 cm, while the S7 sample had the lowest calculated HVL value of 0.0008 cm. Rising sample density causes the MAC to rise, while rising gamma energy causes the MAC to decrease. The highest MAC value recorded was 107 cm2/g at 0.015 MeV in the S7 sample, and the lowest value recorded was 0.0369 cm2/g at 15 MeV in the S1 sample. For all inorganic scintillation samples at particular gamma energies, the standard deviations for the MAC, HVL and Zeff values between the Phy-X/PSD and, Py-MLBUF programs were calculated. With energy range variation, the results for Zeff for the two samples S2 and S4 appeared to be constant. Regards to the fast neutrons, the heights value’s of FNRCS, and MRCS were recorded for S7.

Light Inorganic Scintillation Materials for Neutron and Charge Particle Detection

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

Advanced scintillation materials for calorimetry at circular colliders

The most probable scenario for the development of experimental high-energy physics in the next 50 years is the creation of a family of Future Circular Colliders (FCC) at CERN, a Circular Electron–Positron Collider at China, and a Future Electron-Ion Collider at Brookhaven (USA), which continue the Large Hadron Collider (LHC) scientific program within the framework of the Standard Model and beyond it. The first generation of colliders to be put into operation will utilize the electron beam as one of the colliding species to provide precise mass spectroscopy in a wide energy range. Similarly to the measurements at the high luminosity phase of the LHC operation, the most important property of the detectors to be used in the experimental setup is a combination of the short response of the detectors and their high time resolution. The radiation tolerance to a harsh irradiation environment remains mandatory but not the main factor of the collider’s experiments using electronic beams. A short response in combination with high time resolution ensures minimization of the influence of the pile-up and spill-over effects at the high frequency of collisions (higher than 50 MGz). The radiation hardness of the materials maintains the long-term high accuracy of the detector calibration. This paper discusses the prospects for using modern inorganic scintillation materials for calorimetric detectors at future colliders.

Nanoscale Engineering of Inorganic Composite Scintillation Materials

This review article considers the latest developments in the field of inorganic scintillation materials. Modern trends in the improvement of inorganic scintillation materials are based on engineering their features at the nanoscale level. The essential challenges to the fundamental steps of the technology of inorganic glass, glass ceramics, and ceramic scintillation materials are discussed. The advantage of co-precipitation over the solid-state synthesis of the raw material compositions, particularly those which include high vapor components is described. Methods to improve the scintillation parameters of the glass to the level of single crystals are considered. The move to crystalline systems with the compositional disorder to improve their scintillation properties is justified both theoretically and practically. A benefit of the implementation of the discussed matters into the technology of well-known glass and crystalline scintillation materials is demonstrated.

On the limit of the accuracy of timе stamp at the detection of annihilation γ-quanta with a scintillation detector

An influence of the various relaxation processes of the electronic excitations causing the scintillation in the crystalline compounds under ionising radiation is analysed. It was found that the intracenter relaxation of electronic excitations in the luminescence ion forms a physical limit for the time resolution of the scintillation detector. The limit of the time resolution, which can be provided when measuring the ionising radiation with a scintillation detector, has been established by simulation. A comparison of the time resolution limits for various errors by the electronic part of the ionising radiation detector is performed. It is shown that inorganic scintillation materials based on single crystals activated by cerium ions have a limit of 10 ps, while self-activated scintillators with low yield and short scintillation kinetics may show results not worse than 20 ps. It has been demonstrated that a further increase in the scintillation yield while keeping the short kinetics in self-activated materials can provide a better time resolution in comparison with Ce-activated materials in future detectors.

A Review on X-ray Excited Emission Decay Dynamics in Inorganic Scintillator Materials

Scintillator materials convert high-energy radiation into photons in the ultraviolet to visible light region for radiation detection. In this review, advances in X-ray emission dynamics of inorganic scintillators are presented, including inorganic halides (alkali-metal halides, alkaline-earth halides, rare-earth halides, oxy-halides, rare-earth oxyorthosilicates, halide perovskites), oxides (binary oxides, complex oxides, post-transition metal oxides), sulfides, rare-earth doped scintillators, and organic-inorganic hybrid scintillators. The origin of scintillation is strongly correlated to the host material and dopants. Current models are presented describing the scintillation decay lifetime of inorganic materials, with the emphasis on the short-lived scintillation decay component. The whole charge generation and the de-excitation process are analyzed in general, and an essential role of the decay kinetics is the de-excitation process. We highlighted three decay mechanisms in cross luminescence emission, exitonic emission, and dopant-activated emission, respectively. Factors regulating the origin of different luminescence centers controlling the decay process are discussed.

Time and energy resolution with SPACAL type modules made of high-light-yield Ce-doped inorganic scintillation materials: Spillover and background noise effects

Performance parameters of a composite detection module of Spaghetti type Calorimeter (SPACAL), which is considered for the inner part of the future LHCb Electromagnetic Calorimeter (ECAL) in Upgrade Phase 2, are simulated using GEANT4 software supported by analytical calculations. The accuracy of the timestamp is estimated in both the front and back sections of the composite detector, whereas the energy resolution is estimated for the total signal from the front and back sections of the detector. The rise time of the scintillation response used in the calculations is reconstructed using the results of the coincidence time resolution measurements with annihilation γ-quanta. The time and energy resolutions with PMT readout are compared for Ce-doped garnet- and oxyorthosilicate-type single crystal scintillators without codoping and codoped with aliovalent impurities.

New model for explaining the over-response phenomenon in percentage of depth dose curve measured using inorganic scintillating materials for optical fiber radiation sensors.

Inorganic scintillating material used in optical fibre sensors (OFS) when used as dosimeters for measuring percentage depth dose (PDD) characteristics have exhibited significant differences when compared to those measured using an ionization chamber (IC), which is the clinical gold standard for quality assurance (QA) assessments. The percentage difference between the two measurements is as high as 16.5% for a 10 × 10 cm2 field at 10 cm depth below the surface. Two reasons have been suggested for this: the presence of an energy effect and Cerenkov radiation. These two factors are analysed in detail and evaluated quantitatively. It is established that the influence of the energy effect is only a maximum of 2.5% difference for a beam size 10 × 10 cm2 compared with the measured ionization chamber values. And the influence of the Cerenkov radiation is less than 0.14% in an inorganic scintillating material in the case of OFS when using Gd2O2S:Tb as the luminescent material. Therefore, there must be other mechanisms leading to over-response. The luminescence mechanism of inorganic scintillating material is theoretically analysed and a new model is proposed and validated that helps explain the over-response phenomenon.

Microstructure and luminescence properties of a Ce3+-doped Lu3Al5O12/Al2O3 eutectic grown by the micropulling down method

Inorganic scintillation materials have been widely used in several fields, such as high energy physics, nuclear medical imaging and industrial nondestructive inspection. In this work, a novel scintillation material, (CexLu1-x)3Al5O12/Al2O3 (Ce3+:LuAG/Al2O3) eutectic with different Ce3+-doping concentrations, was successfully grown by the micropulling down method at different pulling speeds. The effects of Ce3+-doping concentration and pulling speed on the microstructure and luminescent properties of the Ce3+:LuAG/Al2O3 eutectic were investigated. The eutectic has a typical garnet structure, and a “Chinese script” microstructure can be seen throughout the cross section. As the pulling speed increased, the grain size and the morphological appearance of the “Chinese script” microstructure decreases. The Ce3+:LuAG/Al2O3 eutectic shows a characteristic Ce3+ emission band centered at 508 nm, and the emission intensity increases with increasing Ce3+-doping concentration until the Ce3+-doping concentration reaches x = 0.01. The eutectic grown at a pulling speed of 1.7 mm/min shows maximum emission intensity, and the light yield of the (Ce0.01Lu0.99)3Al5O12/Al2O3 eutectic excited with X-ray at room temperature is approximately 64% of that of the (Ce0.01Lu0.99)3Al5O12 single crystal. The results reveal that the Ce3+:LuAG/Al2O3 eutectic has a potential application as an X-ray detector material.

Development features of radiation-resistant materials for composite scintillators and wavelength shifting light guides

Abstract The paper discusses the possible processes of radiation-induced changes that occur during irradiation of composite scintillators containing grains of inorganic crystals, and investigates the effect of these processes on radiation resistance of composite systems. All crystalline inorganic scintillation materials contain defects, which can play the role of quenching centres. An irradiation destroys and changes not only the main material of a scintillator but such the centres as well. As a result, the luminescence intensity can grow for a while due to weakening the effect of quenching. In this case, the luminescence spectrum of a scintillator does not change its shape under various accumulated doses D because no new luminescence centres appear. A modification of the properties of the luminescence centres arising under the action of irradiation has to lead to a change in the spectral characteristics of the luminescence. Therefore, the appearance or absence of such the changes is evidence of which centres are predominantly damaged because of irradiation with given dose D. The paper as well discusses the possibilities of obtaining radiation-resistant materials for the development of wavelength shifting light guides for composite scintillators. We investigated samples based on non-luminescent transparent silicone elastomer containing p-terphenyl or 1,4-di[2-(5-phenyloxazolyl)]benzene (POPOP) molecules.

Performance of DSB – a new glass and glass ceramic as scintillation material for future calorimetry

The application of crystalline materials in ionizing radiation detectors has played a crucial role in the discovery of the properties of matter. However, the experiences gathered at high intensity machines such as the LHC have indicated their limitations and underlined the requirements for materials being more tolerable to radiation damage in particular caused by energetic hadrons. Systematic studies of the radiation hardness of inorganic optical and scintillation materials propose both oxide and fluoride crystals composed of atoms with atomic numbers below 60. In this study we report on a cheap glass (BaO*2SiO2) and DSB: Ce glass ceramics even capable for mass production. Admixing gadolinium oxide (Gd3+) even provides a two times larger light yield. Both types of the materials can be produced in a fibre and bulk geometry. This paper summarizes the overall performance and reports on a first test of a 3x3 matrix of large volume samples exposed to energy-marked photons up to 180 MeV.

Study of the New Glass and Glass Ceramic Stoichiometric and Gd3+ -loaded BaO*2SiO2 (DSB:Ce) Scintillation Material for Future Calorimetry

In the last forty years, application of crystalline materials in ionizing radiation detectors has played a crucial role in the discovery of matter properties and promoted a continuous progress in the detecting technique. Further concepts of the detectors at HEP experiments will require an unique combination of the material features, particularly in case of collider experiments. Crucially important becomes a minimal level of radiation damage effects under the electromagnetic part of ionizing radiation and energetic hadrons as well: low deterioration of the optical transmission, low level of afterglow and low level of radioluminescence due to radio-nuclides being generated due to secondary nuclear reactions in the detector material itself. A systematic study of the radiation hardness of inorganic optical and scintillation materials have been performed. We concluded that both oxide and fluoride crystals which consist of atoms with atomic number less than 60 will be reasonably survivable in the irradiation environment of future experiments at colliders. In this study we focused on the study of cheap, capable for a mass production glass (BaO*2SiO2) and DSB: Ce glass ceramics obtained from this glass. We also made this glass more heavy by admixing gadolinium oxide into the matrix. Glass with Gd3+ admixture possesses two times larger light yield than pure (BaO*2SiO2) glass and glass ceramics. Both types of the materials were produced as fibre and blocks of larger volume.

The study of inorganic scintillating materials

The procedure for measuring the temporal characteristics and light output of inorganic scintillating materials excited by β-, γ-, and α-particles from radioactive sources is described. Results of measurements of characteristics are presented for ∼30 scintillating compounds including cerium-doped yttrium silicate and scandium borate; europium-doped strontium phosphate; cerium-doped strontium silicate, calcium silicate and magnesium calcium silicate, etc. Upon β- and γ-excitation, cerium-doped scandium borate gives the highest light output with a fluorescent lifetime of 40 ± 4 ns. The highest light output for α-excitation was from cerium-doped yttrium aluminum perovskite, with a fluorescent lifetime of 29 ± 3 ns.

The Influences of Inorganic Scintillator Optical Fiber Radiation Dosimeter in Some Conditions

In order to meet the increasing demands of modern radiotherapy, real time in-vivo dose measurement has recently attracted significant attention. A small, flexible optical fiber radiation dosimeter, with high signal-to-noise ratio (SNR) that employs inorganic scintillator materials is presented. In this paper, some properties are investigated under special conditions, such as saturation properties when the intensity of the X-Ray is increased and the influence of the temperature of the environment. These properties are important to practical considerations if the sensor is to be successfully deployed in-vivo.

Water-equivalent fiber radiation dosimeter with two scintillating materials.

An inorganic scintillating material plastic optical fiber (POF) dosimeter for measuring ionizing radiation during radiotherapy applications is reported. It is necessary that an ideal dosimeter exhibits many desirable qualities, including water equivalence, energy independence, reproducibility, dose linearity. There has been much recent research concerning inorganic dosimeters. However, little reference has been made to date of the depth-dose characteristics of dosimeter materials. In the case of inorganic scintillating materials, they are predominantly non water-equivalent, with their effective atomic weight (Zeff) being typically much greater than that of water. This has been a barrier in preventing inorganic scintillating material dosimeter from being used in actual clinical applications. In this paper, we propose a parallel-paired fiber light guide structure to solve this problem. Two different inorganic scintillating materials are embedded separately in the parallel-paired fiber. It is shown that the information of water depth and absorbed dose at the point of measurement can be extracted by utilizing their different depth-dose properties.

The Influence of Oxygen Vacancies on Luminescence Properties of Na3LuSi3O9:Ce3+

Oxygen vacancies play an important role in the luminescence processes of inorganic scintillator materials. In order to study the effects of oxygen vacancies on the luminescence properties of Na3LuSi3O9:Ce3+, these phosphors were prepared using a high temperature solid-state reaction method under different atmosphere and raw materials. It was found that oxygen vacancy had great influence on the absorption, photoluminescence and decay curves of Na3LuSi3O9:Ce3+. The luminescence intensity and peak position showed a regular change when synthesizing atmosphere changed. Na3LuSi3O9:Ce3+ with more oxygen vacancies showed much stronger luminescence intensity at high temperature than that without vacancies. And it was also found that the decreasing of oxygen vacancies can quicken the photoluminescence decay of Ce3+ in Na3LuSi3O9. The existence of oxygen vacancies in Na3LuSi3O9:Ce3+ was confirmed by Zr4+ doping and thermoluminescence emission spectra. At last, emission bands of Ce3+ and oxygen vacancies were well di...

Inorganic Scintillation Crystals for Neutron Detection

Inorganic scintillators play an important role in the detection and spectroscopy of gamma and X-rays, as well as in neutrons and charged particles. For a variety of applications, new inorganic scintillation materials are being studied. New scintillation detector applications arise continuously and, consequently, the interest in the introduction of new fast scintillators becomes relevant. Scintillation crystals based on cesium iodide (CsI) have relatively low hygroscope, are of easy handling and low cost, features that favor their use as radiation detectors. In this work, lithium and bromine doped CsI crystals were grown using the vertical Bridgman technique. In this technique, the charge is maintained at high temperature for 10 h for the material melting and complete reaction. The temperature gradient 21 °C/cm and 1 mm/h descending velocity are chosen as technique parameters. After growth is finished, the furnace is cooled at a rate of 20 °C/h to room temperature. The concentration of the lithium doping element (Li) studied was $10 ^{-3} ~\mathrm {M}$ and the concentration of the bromine was $10 ^{-2} ~\mathrm {M}$ . Analyses were carried out to evaluate the scintillators developed concerning the neutron from the AmBe source with energy range of 1 MeV to 12 MeV [1] . Lithium can capture neutrons without gamma-ray emission, thus, reducing the back-ground. The neutron detection reaction is $^{6}\mathrm {Li}(\mathrm {n},\alpha ) ^{3} \mathrm {H}$ with a thermal neutron cross section of 940 barns. In this paper, the feasibility of the CsI:Li and CsI:Br crystals as neutron detectors for monitoring was investigated, due to the fact that in our work environment there are two nuclear research reactors and calibration systems.

Limits of Inorganic Scintillating Materials to Operate in a High Dose Rate Environment at Future Collider Experiments

This report gives a review of the radiation damages induced by gammas and energetic hadrons in inorganic scintillating materials. We discuss the creation and recovery of color centers in scintillating materials under gamma and high energy proton irradiation, the two main causes of irradiation in High Luminosity LHC. The induced phosphorescence and the production of radioisotopes in heavy and light inorganic scintillators and in surrounding construction materials, as well as their influence on the possible design of the detector working in a high dose rate environment, are also described.

Conference comments by the Editors

The international community of researchers on fundamentals, development, and applications of inorganic scintillator materials has found the biennial meetings of the SCINT series to be an excellent chance to exchange data and ideas. These can range from very basic physical concepts and atomistic mechanisms in the materials under study up to truly application-minded tasks and problems defined by the modern needs for radiation detection, imaging, and spectroscopy of many kinds. The 12th International Conference on Inorganic Scintillators and their Applications (SCINT 2013) was organized by the Shanghai Institute of Ceramics, Chinese Academy of Sciences, in Shanghai, April 15-19, 2013. There were in total 180 scientific contributions, 85 oral presentations, 17 invited talks, and 95 poster exhibitions presented by 147 participants from 18 different countries. This special issue of the IEEE TRANSACTIONS ON NUCLEAR SCIENCE comprises the selected and refereed original works based on the SCINT 2013 presentations, altogether 51 papers. The conference was technically and financially co-sponsored by the Chinese Academy of Sciences, and Nuclear and Plasma Sciences Society (IEEE). The SCINT 2013 conference organizers acknowledge with deep thanks also the sponsorship and support of seven domestic and foreign industrial companies participating in the conference exhibition.

Czochralski Growth and Properties of Scintillating Crystals

The Czochralski method is one of the very few melt growth techniques that are industry friendly when considering the combination of quality, dimensions, and cost of the produced crystals suitable for their commercialization in scintillation detectors. This method is one of the oldest and most developed crystal growth processes regarding an adequate understanding the physical phenomena observed during solidi cation process and its practical expansion especially in the industrial scale production. It allows controllable formation of single-crystalline cylindrical ingots of various inorganic scintillation materials. The review summarizes recent progress on the Czochralski growth of a number of scintillation materials. The oxide crystals are mainly considered including the Ce and Pr-doped RE3Al5O12, RE = Y, Lu, aluminum garnets and newly discovered ultrae cient Ce-doped Gd3(Ga,Al)5O12 multicomponent garnet, high density PbWO4 and CdWO4 tungstates, Ce-doped RE2SiO5, RE = Y, Gd, Lu, oxyorthosilicates and (Y,Lu)AlO3 aluminum perovskites and nally the classical Bi4Ge3O12 scintillator. Additionally, the details of the growth of other practically important non-oxide crystals, namely the Ce and Eu-doped LiCaAlF6 neutron and ultrae cient Ce-doped LaBr3 scintillators, are discussed. The potential of novel micro-pulling down growth method is brie y described in the combinatorial search for new scintillator materials. Selected luminescence and scintillation characteristics including the spectra and decay kinetics, light yield and radiation resistance are also illustrated and overviewed.