Scintillation Efficiency Research Articles

Suitability of nanoparticles for gamma-ray applications

While measuring the relative gamma-to-electron conversion efficiencies of nanoparticles by incorporating them into plastic scintillator and comparing the number of counts in pulse height spectrum for gamma-rays from 241Am, WO3, and PbO nanocomposites offered lesser scintillation counts than their unloaded counterparts. As investigated, these nanoparticles absorb a major portion of outgoing electron energy such that exiting electrons turn incapable of scintillating the medium. This observation hints why only selected species of nanoparticles successfully enhance the gamma-counting efficiency of plastic scintillators.

TL and OSL as research tools in luminescence: Possibilities and limitations

The objective of this paper is to review the use of the thermoluminescence (TL) and optically stimulated luminescence (OSL) techniques as research tools in luminescence, particularly to detect the presence of trapping centers that can degrade the efficiency of scintillators, and shape the properties of persistent phosphors, storage phosphors and dosimeters. A brief review of the main analysis techniques is provided, followed by a discussion of their limitations. Examples of applications in which the TL or OSL analyses have provided useful information on the trapping and recombination of charges created by ionizing radiation is given.

Effect of Gd2O3 concentration on photo and X-rays excited luminescence characteristics of Dy3+-Activated Li2O3–SrO–B2O3 glass

Gd3+ and Dy3+-doped borate glasses are considered attractive candidates for white light emission. In this work, the samples, developed by the melt-quenching route, contain a mixture of Gd3+ and Dy3+ with known molar compositions. The determined physical parameters indicate structural changes. Information regarding the Judd-Ofelt (JO) intensity parameters and spectral radiative features, calculated from absorption spectra and emission properties, respectively, are obtained. Excitation and photoluminescence characteristics of the developed samples are found. The energy transfer (ET) efficiency from Gd3+ → Dy3+ is determined by considering their emission intensities and lifetime. The quantum efficiency (QE) of glasses is evaluated. Inokuti –Hirayama (IH) model shows that the Dy3+ → luminescence center ET is dominated by dipole-dipole coulomb interaction. Due to the excitation of more secondary electrons, the X-ray luminescence shows an intense emission pattern. Furthermore, we find the integral scintillation efficiency to be 8.4% of the commercial BGO scintillator crystal for the 10 mol% Gd2O3-doped glass. Commission International deI’Eclairage (CIE) color coordinates and color correlated temperature (CCT) show the suitability of tested samples for white-light applications.

Photo-induced preparation of Ce-doped terbium aluminum garnet and its luminescent properties

Ce(III) activated terbium aluminum garnet (Tb3Al5O12:Ce, TAG:Ce) powder as a luminescent phosphor was synthesized by the photo-induced method. The irradiation of an aqueous solution containing formate anions and soluble salts of both metal ions by UV light led to the precipitation of an amorphous solid phase. Subsequent heat treatment at 1200 °C resulted in the crystallization of the TAG:Ce phase-pure garnet structure. The structure and morphology of the products were investigated by X-ray powder diffraction (XRPD) and by scanning electron microscopy (SEM). The particle size, evaluated by transmission electron microscopy (TEM), ranges from 50 to 150 nm. The manufactured Ce-doped TAG features intensive luminescence corresponding to Ce(III) 5d–4f transitions at 559 nm. Due to its high density, chemical stability, non-toxic character, and excellent scintillation efficiency, the application of Ce-doped TAG nano-powder in photodynamic therapy and preparation of optical ceramics was suggested.

A large area efficient trigger scintillator with SiPM read out

A large area plastic scintillator detector system with SiPM read out has been prepared in order to improve the trigger selectivity for reaction studies induced by an intense proton beam with a beam momentum of several GeV/c. The system consists of six trapezoidal modules, each with three plastic scintillator elements that are each equipped with 12 SiPMs. The detection of a charged particle is based on registering coincident signals in several SiPMs. By requiring a signal on at least two of the SiPMs, the noise rate is negligible and a detection efficiency close to 100% is achieved.

Transparent Microcomposite Films Based on a Ce-Doped Li6Gd(BO3)3 Scintillator for Radiation Detection.

Scintillators are widely used for high-energy radiation detection. Hybrid inorganic–organic composite scintillators with high light yields, high light decay rates, excellent stability, and low costs are in great demand. Here, we report a novel scintillator composed of Ce-doped Li6Gd(BO3)3 (LGBO) microphosphors (MPs) and polymethyl methacrylate for X-ray and thermal neutron detection. The Ce-doped LGBO MPs, fabricated using a facile high-temperature solid-state reaction method, exhibit intense blue light at 416 nm under X-ray and UV excitation and have a high photoluminescence quantum yield of ∼63%. More importantly, the composite scintillator based on these MPs has excellent transparency and luminescence intensity. The luminescence integral intensity of composite scintillators is superior to that of commercial CsI:Na under X-ray excitation, and the light yield under thermal neutron irradiation is 21,000 photons/thermal neutron. The scintillation decay time is found to be below 600 ns. The neutron−gamma signal discrimination and neutron detection efficiency of the composite scintillators are acceptable for practical application. There is an excellent separation between neutron and background events. It represents significant improvements in scintillator performances, especially for reliable thermal neutron scintillators that are likely to improve the data qualities of scientific instruments, including charge-coupled device-based imagers and Anger logic-based position-sensitive detectors in neutron user facilities.

Optical, luminescence, and energy transfer studies of Gd3+/Dy3+ doped potassium gadolinium borophosphate glasses

The K2O–Gd2O3–B2O3–P2O5 glass doped with Dy2O3 (Dy:KGPB) were synthesized by the melt-quenching technique. These glasses were subjected to characterize the physical, structure, optical and luminescence properties. It was observed that the density, molar volume and refractive index of glass increased with increasing Dy2O3 concentration. The FTIR result confirmed the main glass network of BOB and POP linkages those were degraded by adding Dy2O3 modifier. Glasses absorbed photons in ultraviolet, visible light and near-infrared region. The photoluminescence under direct Dy3+ excitation performed the strong emissions at 574 and 482 nm corresponding to 4F9/2 → 6H13/2 and 4F9/2 → 6H15/2 transition, respectively. The Gd3+ excitation also caused strong emission of Dy3+ by the Gd3+-Dy3+energy transfer. Glass doped with 1.00 mol% of Dy2O3 owned the highest emission intensity due to the concentration quenching. The lifetime of 4F9/2 level was found to decrease with addition of Dy2O3 content via dipole-diploe interaction between Dy3+ ion. Judd-Ofelt (J-O) intensity parameters were initially calculated and applied to evaluate the radiative parameters such as branching ratios, radiative transition probabilities, and stimulated emission cross-sections. The radioluminescence of glass was also investigated and found the scintillation efficiency around 15.6%, compared to BGO scintillator. The Dy:KGPB glass has an interesting potential for solid-state laser, LED and X-ray detection applications.

Aggregation-Induced Fluorescence Enhancement for Efficient X-ray Imaging Scintillators and High-Speed Optical Wireless Communication

Aggregation-Induced Fluorescence Enhancement for Efficient X-ray Imaging Scintillators and High-Speed Optical Wireless Communication

Performance of a scintillation imaging system for relative dosimetry in pencil beam scanning proton therapy

The proton spot scanning system requires extensive periodic quality assurance procedures to guarantee the conformality of planned dose distribution to the tumor. Detectors with stable, accurate, and fast data acquisition properties make the quality assurance procedures more efficient. For this purpose, a camera-based scintillation imaging system has been developed. A high scintillation efficiency screen coupled with a high-performance camera improved the dose sensitivity and precision required for the measurements. The dose distribution within the scintillating screen can be analyzed from the captured light distribution image in a relatively straightforward way.In this study, we investigated the performance of a 2D detection system by using a scintillating screen (silver-activated zinc sulfide powder deposited on the surface of a plastic scintillator HND-S2) for dose distribution measurement. The characteristics of the system in terms of response reproducibility, linear dose–response, and beam spot size dependence on proton dose were assessed in a series of proton irradiations. To evaluate the accuracy of lateral dose profiles measured by the ZnS: Ag based scintillating screen, we compared the results with plastic scintillator BC-408 and some commercial quality control devices. Several measurements were conducted with proton energies ranging from 70–235 MeV. We found that the detector showed stable response reproducibility (better than 1.6%) and good dose–response linearity (R2¿0.999). The beam spot size was independent of proton dose when the response of the pixel value was between 10% and 90% of the maximum. The in-air spot size measured by the ZnS: Ag based scintillating screen was found to be slightly smaller than the Lynx detector while the BC-408 showed a slightly bigger spot size. The inter-comparison results for scanned fields showed good agreements. The observed differences in beam profile measurement between the inorganic and organic scintillating screens were mainly due to their optical properties and structures. The developed scintillation imaging system with an effective resolution of 0.12 mm proved to be a reliable device for efficiently performing the quality checks for two-dimensional proton dosimetry.

Highly efficient blue emissive copper halide Cs5Cu3Cl6I2 scintillators for X-ray detection and imaging

In recent years, copper-based halide scintillators have attracted tremendous attention due to their excellent luminescent properties and low manufacturing costs. Herein, a high-performance and low-cost Cs5Cu3Cl6I2 scintillator is prepared by simple mechanical grinding. The mixed-halide Cs5Cu3Cl6I2 phosphor exhibits a blue emission centered at 475 nm with a large stokes shift, originating from the self-trapped exciton emission of Cu sites. The photoluminescence quantum yield (PLQY) of Cs5Cu3Cl6I2 can be increased to 88.4% from 20.4% by the efficient suppression of the anion vacancy defects. In addition, the Cs5Cu3Cl6I2 scintillator shows a high steady-state X-ray to light conversion efficiency of about 57000 photons/MeV, good X-ray linear response, and low detection limit of 71.9 nGyair/s. The X-ray imaging results based on the Cs5Cu3Cl6I2 scintillator screen display a high spatial resolution of 9.0 line-pairs per millimeter (lp/mm). Furthermore, Cs5Cu3Cl6I2 exhibits good radiation stability under a total dose of 113.58 Gyair. Overall, the Cs5Cu3Cl6I2 scintillator prepared by mechanical grinding method has the advantages of low cost, high efficiency, and good radiation resistance, suggesting its huge potential in X-ray detection and imaging.

Efficient liquid scintillator loaded with a light-emitting conjugated oligomer for beta- and gamma-ray spectroscopic measurements

Liquid scintillation (LS) counting is a common way to detect and measure radioactivity because it has a better time resolution and can discriminate between neutrons and gamma rays. We show how to make a promising liquid scintillator with a light-emitting conjugated oligomer: 9,9,9′,9′,9″,9″-hexakis(octyl)-2,7′,2′,7″-trifluorene (ADS038FO or 9HOTF). A container with a LS blend coupled with a photomultiplier detector setup showed enhanced scintillation for different radioactive sources. The gamma and beta radiation responses of LS were studied under various radiation sources: 137Cs, 60Co, and 22Na as gamma rays and 90Sr as a beta source. We observed a scintillation count increase with an increase in the percentage of 9HOTF. Further studies were performed to evaluate the characteristics of the fabricated liquid scintillator, such as emission wavelength, absorption, Compton edge (CE), and count rate. CE spectra were used to calibrate the energy, and the pulse height spectra were measured for the prepared LSs. The energy linearity was investigated, and the fabricated LSs showed more than 99% energy linearity. According to the results, the CE determined was more than 90% of the theoretical values for the 137Cs, 60Co, and 22Na sources. For the 90Sr/90Y beta source, the pulse height spectrum's lower energy (90Sr) and the higher energy (90Y) were distinguishable. The comparison between POPOP and 9HOTF-based LS proved that the performance of 9HOTF was marginally better than that of POPOP.

Rare earth-doped LiLuF4 microcrystalline for high-efficiency scintillation and X-ray imaging applications

Scintillators play a vital role in high-energy physics, medical imaging, security inspection, etc. Here, we designed and prepared a highly efficient scintillator of Ce,Tb-codoped LiLuF4, which was synthesized by a hydrothermal method using low-cost raw materials. The microcrystalline scintillator exhibits the strong luminescence of rare earth ion, which has a characteristic green fluorescence emission with a quantum yield of 71.59%. This material has a strong X-ray response, superior light output (16,509 ph/MeV), excellent ray cut-off capability and absolute stability. Based on micron-level powdered compounds, we used direct coating to manufacture a scintillation film with a size of 5.5 cm × 8.0 cm for X-ray imaging testing. The imaging test shows that the highly stable scintillation film not only has a spatial resolution capability of more than 10.0 LP/mm but also has great potential to be prepared as a flexible scintillator, which exhibited excellent performance as an potential scintillation detection material.

Luminescence and energy transfer properties of Gd3+ and Dy3+ in borosilicate glasses for tunable emission materials

This work investigates the physical, optical, luminescence, and scintillation properties of borosilicate glasses doped with different concentrations of Gd2O3 and Dy2O3. All glasses were prepared by the melt quenching technique. The density and molar volume value increase as the Gd2O3 and Dy2O3 content increases. Dy3+ in glasses absorb photons in visible light and near-infrared regions, confirmed by the absorption spectra. The emission spectra of glasses show two strong peaks at 575 nm (4F9/2→6H13/2) and 481 nm (4F9/2→6H15/2) under Gd3+, direct Dy3+ and X-ray excitation. The integral scintillation efficiency of 1.50Dy:12.5Gd is 7.22%, compared with BGO crystal. The luminescence of glass can be tuned for different shades of white emission by selecting the excitation source such as photon with 275 nm, 387 nm and X-ray, respectively. The developed glasses are the potential for tunable emitting and scintillation material applications.

Effect of Gd2O3 in Li2O–AlF3–CaF2–P2O5–Eu2O3 glasses for laser medium and X-rays detection material applications

The glass formula of 20Li2O+10AlF3+2.5CaF2+(66.5-x)P2O5+xGd2O3+1Eu2O3 (PLACEu1Gdx), where x = 2,4,6,8,10 mol% have been prepared by conventional melt-quenching technique. These glasses' optical absorption, photoluminescence, decay time, and radioluminescence have been measured at room temperature. Judd-Ofelt's (J-O) analysis of PLACEu1Gd8 has been investigated and the magnitude of parameters follows the trend as Ω2>Ω4>Ω6. The important laser parameters such as radiative properties are calculated using J-O parameters and luminescence spectra. The decay time with the transition from the 5D0 level was estimated under 274 nm and 394 nm excitation using bi-exponential fitting. CIE coordinates, CCT and intensity ratio have been calculated for glass samples. The integral scintillation efficiency of PLACEu1Gd8 is 31% compared with BGO crystal. The PLACEu1Gdx glasses are promising for laser medium and x-rays detection material applications.

X-ray induced optical luminescence and energy transfer mechanism from Gd 3+ to Tb3+ ions in fluorophosphate scintillating glasses for X-ray detecting material

Tb3+-doped gadolinium aluminium sodium fluorophosphate scintillating glasses were synthesized by the melt-quenching method. The photoluminescence and X-ray induced optical luminescence were investigated with the concentration of Tb2O3. For photoluminescence (PL) results, Tb3+ ions activated in glasses emit intense green emission peaking at 543 nm by stimulating at 220, 275, and 377 nm. Among three excitations, the wavelength at 275 nm presented the energy transfer mechanism from Gd3+ to Tb3+ in glasses. The efficient energy transfer was analyzed via faster lifetime with increasing concentrations of Tb2O3. According to their PL spectra, the emission intensity is increased up to 5.0 mol%, then, start to decrease with further increasing of Tb3+ concentration because of concentration quenching effect. Moreover, the 6.5 mol% of Tb3+ in PGNA glasses showed the largest luminescence intensity under X-ray. The integral scintillation efficiency has been studied and exhibited the highest value at 210% when comparing to commercial Bi4Ge3O12 scintillation crystal. All results are pointed out the appropriate potential to be X-ray detecting material.

Development of an energy and efficiency calibration method for stilbene scintillators

A method for calibrating the energy scale and detection efficiency of stilbene scintillators is presented herein. This method can be used to quantitatively analyze the Compton continuum of gamma-ray spectra obtained using such scintillators. First, channel–energy calibration was conducted by fitting a semiempirical equation for the Compton continuum to the acquired energy spectrum and a new method to evaluate the intrinsic detection efficiency, called intrinsic Compton efficiency, of stilbene scintillators was proposed. The validity of this method was verified by changing experimental conditions such as the number of sources being measured simultaneously and the detector–source distance. According to the energy calibration, the standard error for the estimated Compton edge position was ±1.56 keV. The comparison of the intrinsic Compton efficiencies calculated from the single- and two-source spectra showed that the mean absolute difference and the mean absolute percentage difference are 0.031 %p and 0.557%, respectively, demonstrating reasonable accuracy of this method. The feasibility of the method was confirmed for an energy range of 0.5–1.5 MeV, showing that stilbene scintillators can be used to quantitatively analyze gamma rays in mixed-radiation fields.

Luminescence and Judd-Ofelt analysis of gallium aluminum gadolinium yttrium borate scintillating glass doped with Dy3+

In this work, Dy3+:B2O3–Ga2O3–Al2O3–Gd2O3–Y2O3 glasses system were prepared by melt quenching technique. The physical, chemical groups, optical, photoluminescence and radioluminescence properties of glasses were investigated. The density and refractive index tended to increase with increasing Dy2O3 concentration. The Dy3+ doped glasses absorbed photon in UV, VIS and NIR region in the absorption spectra. For photoluminescence study, the 276 and 351 nm wavelength owned the strong excitation peak, so they were used to measure the emission spectra. The main emission peak of Dy3+ showed at 487 and 575 nm with 4F9/2 → 6H15/2,13/2 transition due to both direct excitation and the Gd–Dy energy transfer. The luminescence lifetime of Dy3+ was in the milliseconds order that shortened with adding Dy2O3 content. The PL emission intensity at 100 K was around 1.48 times compared to its value at room temperature (∼300 K). The Judd-Ofelt theory was used to analyse the radiative properties of glass and its result performed the quantum efficiency around 63.75%. The X-rays induced optical luminescence represented the highest intensity in 0.50 mol% Dy2O3-doped glass similarly to the photoluminescence under 351 nm excitation. The X-rays scintillation efficiency of this glass is 14% compared with BGO crystal. The developed glass in this work owns the potential for X-rays detection material with integration mode usage, and is also interesting for white light source and laser medium applications.

Two d10 2D Cathode-Ray Scintillation Coordination Polymers with High Efficiency and High-Voltage Stability.

Two examples of efficient cathode-ray scintillation coordination polymers with good stability at high voltage were prepared by conjugating luminescent groups with d10 metal ions. The synergistic effect of inorganic metal and organic ligand suppresses the self-quenching of the conjugated luminescent groups and enhances the scintillation performance. This work provides new ideas for the design of new field-emission displays and cathode-ray scintillation materials.

Nanoscale Gd2O2S:Tb Scintillators for High-Resolution Fluorescent Imaging of Cold Neutrons

Cold neutron has a strong ability to penetrate metal materials and identify light elements, making it an ideal nondestructive testing technique for detecting cracks, bubbles, or other defects in metals. However, the low imaging resolution and detection efficiency of scintillators limit the application of cold neutron technology in imaging. The particle size and luminescence properties of scintillator materials have an important influence on the spatial resolution and detection efficiency of cold neutron radiography. Here, we report a series of NaF-doped Gd2O2S:Tb3+ (NaF-d-GOS:Tb) scintillators with adjustable particle size, which were prepared through a two-step method of solution precipitation followed by solid-phase vulcanization calcination. It was found that the NaF-d-GOS:Tb scintillators showed the highest quantum yield, reaching up to 62.94%. They were applied to fabricating cold neutron ultrathin screens. The resolution can reach 12 μm in the cold neutron imaging system. These NaF-d-GOS:Tb scintillators with excellent fluorescence facilitate the development of nondestructive testing techniques based on cold neutron imaging.

Aryl group grafted polysilane: novel scintillation solute for high efficiency and environment-friendly scintillator

Aryl group grafted polysilane: novel scintillation solute for high efficiency and environment-friendly scintillator