Scintillation Decay Time Research Articles

Scintillation and photoluminescence properties of Cs2NaY1−x Pr x Cl6 crystals

Herein, Cs2NaY1−x Pr x Cl6 crystalline scintillators have newly been fabricated and characterized. The crystals exhibited emission bands at ∼300 and ∼500 nm, which originated from the 5d–4f and 4f–4f transitions of Pr3+ ions, respectively, and the scintillation decay time constants were 19–29 and 170–370 ns, respectively. The former was attributed to the emissions from the 5d–4f transitions of Pr3+ ions, whereas the latter was attributed to the host materials. The light yields of these crystals were higher than those of undoped Cs2NaYCl6 crystals. The Cs2NaY0.4Pr0.6Cl6 crystal exhibited the highest light yield (7100 photons MeV−1), which is approximately four times higher than that of the undoped Cs2NaYCl6 crystal (1800 photons MeV−1).

Optical and scintillation properties of Nd-doped Lu2Si2O7 single crystals

Lutetium pyrosilicate (Lu2Si2O7, LPS) single crystals were synthesized by the floating-zone method with different dopant concentration to investigate the Nd-concentration dependence on the photoluminescence (PL) and scintillation properties. The Nd-doped LPS presented PL peaking at 800–900 nm due to the 4–4f transitions with the PL quantum yield up to 34%. Under X-ray irradiation, the samples showed several sharp peaks in both UV–visible and NIR regions. The scintillation decay time constants were around 3–4 μs upon pulsed X-ray excitation, and the afterglow level at 20 ms after X-ray irradiation was 310–650 ppm. The scintillation light yields of the Nd-doped LPS under γ-rays from 137Cs were up to 800 ph/MeV. hMeV.

Metal Halide Scintillators with Fast and Self‐Absorption‐Free Defect‐Bound Excitonic Radioluminescence for Dynamic X‐Ray Imaging

AbstractScintillators for radiation detection are of great significance in medical imaging, security, and nondestructive inspection. The current challenge for scintillators is to simultaneously achieve high scintillation light yield, fast radioluminescence, simple film fabrication, large X‐ray attenuation efficiency as well as stable and nontoxic compositions; no previous scintillators fulfill all the above requirements. Here, metal halide Rb2AgBr3, possessing defect‐bound excitonic radioluminescence, is shown as efficient and fast scintillators. This nontoxic and stable scintillator emits from excitons bound to neutral bromine vacancies, enjoying an efficient and spin‐allowed fast emission with minimized self‐absorption. Rb2AgBr3 thus has a high light yield (25 600 photons MeV−1), fast scintillation decay time (5.31 ns), and a record value of light yield versus decay time (4821 photons MeV−1 ns−1). The close‐space sublimation method is developed for fast and scalable fabrication of oriented Rb2AgBr3 films. The scintillator film is further integrated with commercial flat‐panel imagers, and the spatial resolution reaches 10.2 line pairs per millimeter at the modulation transfer function of 0.2, doubling the resolution of conventional CsI:Tl flat‐panel detectors. The dynamic X‐ray imaging and its use to real‐time monitoring of bone movement without ghosting effect is also demonstrated.

TlSr2I5:Eu2+- A new high density scintillator for gamma-ray detection

In this paper we report on the scintillation properties of TlSr2I5 doped with Eu2+, a novel thallium-containing high-resolution scintillator for gamma-ray spectroscopy. Small diameter, good quality crystals of TlSr2I5:Eu (TSI) with different Eu2+ concentrations were grown by the vertical Bridgman method. X-ray diffraction measurements show that single crystals of TSI belong to the monoclinic system with space group P21/c. TlSr2I5 has a density of 5.32 g/cm3 and effective Z of 60. The X-ray excited emission of Eu2+ doped TlSr2I5 features a broad emission band peaking between 460–470 nm. The light yield of TlSr2I5 crystal doped with 1% Eu2+ is measured to be ∼72,000 ph/MeV with an energy resolution of 2.8% at 662 keV. The scintillation decay time which is characteristic of Eu2+ shows two components, with ∼90% of the light in a ∼500 ns component and the rest in a longer component of ∼3 μs.

Photoluminescence and scintillation properties of Ce-doped SrLu2O4 single crystals

Undoped and Ce-doped SrLu2O4 single crystals were synthesized by the floating zone method equipped with four Xe lamps, and the photoluminescence (PL) and scintillation properties were investigated. A broad emission band appeared at around 470 nm in PL and scintillation spectra due to the 5d–4f transition of Ce3+. In addition, the PL and scintillation decay time constants were close to typical values of the 5d–4f transition of Ce3+. The pulse height spectra of 137Cs gamma-ray demonstrated that the light yield of undoped and 0.3% Ce-doped SrLu2O4 were 1490 and 570 photons/MeV, respectively. In addition, relationship between gamma-ray energy and photoabsorption peak channel was evaluated.

Photoluminescence and scintillation properties of Yb2+-doped SrCl2−xBrx (x = 0, 1.6, 2.0) crystals

Photoluminescence (PL) and scintillation properties are reported for SrCl2−xBrx:Yb2+ (x = 0, 1.6, 2.0) crystals grown by a self-seeding solidification method. Two emission peaks centered at approximately (380–390) nm and (410–420) nm were observed in PL and scintillation spectra and are attributed to spin-allowed and spin-forbidden Yb2+ 5d–4f transitions, respectively. SrCl0.4Br1.6:Yb2+ showed the highest light yield of 71 000 photons MeV−1 with a scintillation decay time constant of 490 ns. The developed SrCl0.4Br1.6:Yb2+ materials have the potential to replace conventional SrI2:Eu2+ scintillators used in pulse counting mode detectors owing to their high light yields and low deliquescence.

On fast LuAG:Ce scintillation ceramics with Ca2+ co‐dopants

Abstract“Defect engineering” was a valid strategy to modify the performance of LuAG:Ce scintillator, usually realized by Me2+/Me+ co‐doping. To investigate the effects of Ca2+ co‐doping on the scintillation properties of LuAG:Ce, a set of LuAG:Ce ceramics with Ca2+ concentrations ranging from 0 to 0.5 at.% were manufactured. The absorption spectra, radioluminescence spectra (RL spectra), light yield, RL spectra as a function of temperature, decay time, and TSL curves of the ceramic products were carefully measured. With Ca2+ co‐doping, the scintillation performance of LuAG:Ce ceramics was greatly improved. Especially for the 0.2 at.% Ca2+ co‐doped one, it has a high light yield value of 24, 400 ph/MeV, a fast scintillation decay time of 48 ns, and a small slow component contamination. And the role of Ca2+ in the scintillation mechanism of LuAG:Ce ceramics was also discussed in this paper.

Multimodal Non-Contact Luminescence Thermometry with Cr-Doped Oxides.

Luminescence methods for non-contact temperature monitoring have evolved through improvements of hardware and sensor materials. Future advances in this field rely on the development of multimodal sensing capabilities of temperature probes and extend the temperature range across which they operate. The family of Cr-doped oxides appears particularly promising and we review their luminescence characteristics in light of their application in non-contact measurements of temperature over the 5–300 K range. Multimodal sensing utilizes the intensity ratio of emission lines, their wavelength shift, and the scintillation decay time constant. We carried out systematic studies of the temperature-induced changes in the luminescence of the Cr3+-doped oxides Al2O3, Ga2O3, Y3Al5O12, and YAlO3. The mechanism responsible for the temperature-dependent luminescence characteristic is discussed in terms of relevant models. It is shown that the thermally-induced processes of particle exchange, governing the dynamics of Cr3+ ion excited state populations, require low activation energy. This then translates into tangible changes of a luminescence parameter with temperature. We compare different schemes of temperature sensing and demonstrate that Ga2O3-Cr is a promising material for non-contact measurements at cryogenic temperatures. A temperature resolution better than ±1 K can be achieved by monitoring the luminescence intensity ratio (40–140 K) and decay time constant (80–300 K range).

Effects of europium concentration on luminescent and scintillation performance of Cs0.2Rb0.8Ca1−xEuxBr3 (0 ≤ x ≤ 0.08) crystals

A series of Cs0.2Rb0.8Ca1–xEuxBr3 (0 ≤ x ≤ 0.08) crystals doped with different concentrations of Eu2+ were grown using the Bridgman-Stockbarger method. The work describes the influence of Eu2+ concentration on the luminescent and kinetic properties of Cs0.2Rb0.8Ca1–xEuxBr3 crystals, as well as on their scintillation performance. The maximum in the radioluminescence spectra of these crystals shifts from 439 to 446 nm with increasing europium concentration. The scintillation decay times of Cs0.2Rb0.8Ca1–xEuxBr3 lengthen with the Eu2+ content. The best light output of 33600 photons/MeV is obtained for Cs0.2Rb0.8Ca0.93Eu0.07Br3, and the best energy resolution of 6.9% is found for Cs0.2Rb0.8Ca0.94Eu0.06Br3.

Photoluminescence and scintillation characteristics of Ce-doped CaLaAl3O7 crystalline scintillators for detecting alpha particles

Undoped and Ce-doped CaLaAl3O7 crystals were synthesized by the optical floating zone method and photoluminescence and scintillation properties were evaluated. A broad peak at 420 nm due to the 5d-4f transitions of Ce3+ is observed from the Ce-doped samples based on the measurement of photoluminescence and scintillation spectra. The photoluminescence and scintillation decay time constants attributable to the 5d-4f transitions of Ce3+ are obtained in the Ce-doped samples. The 1.0% and 3.0% Ce-doped samples show relatively high scintillation light yields of 230–260 ph/5.5 MeV-α from pulse height analysis under irradiation of α-rays from 241Am. The best afterglow level is 160 ppm in the 3.0% Ce-doped sample among the present samples.

Fabrication and scintillation characterizations of high concentration Ce[formula omitted] doped BaF2 transparent ceramic

In this study, high concentration (5 mol%) of cerium doped barium fluoride transparent ceramic was fabricated by hot pressing method t a temperature of 1200 °C under 30 MPa. XRD (X-ray Diffraction), SEM (Scanning Electron Microscope), PLE (Photoluminescence Emission) measurements was used to investigate the phase composition, microstructure as well as photoluminescence properties of Ce3+: BaF2. XEL (X-ray Excited Luminescence) and pulse height spectrum were used to investigate the scintillation properties of this ceramic. The phase composition and microstructure analyses showed that the Ce3+: BaF2precursor nanoparticles prepared by the co-precipitation method were uniform and have a average size of 25 nm. The highest transmittance of the ceramic was 77% at the wavelength of 2300 nm. The PL (photoluminescence) spectrum showed that the 5d–4f transition of Ce3+: BaF2 transparent ceramic is located at 340 nm. X-ray excited luminescence exhibited only one violet peak at 392 nm. Scintillation decay time measurements showed only a slow component of 437 ns under 662 keV gamma excitation.

Tm concentration dependence of scintillation characteristics on Tm-doped Lu2Si2O7 single crystal

Lutetium pyrosilicate (Lu2Si2O7) single crystals were synthesized by using the floating-zone method with 0.1, 0.5, 1.0, 2.0 and 5.0% of Tm-doping concentration. After the phase confirmation by powder XRD, photoluminescence (PL) and scintillation properties were systematically measured, including PL emission map, PL decay time, scintillation spectra, scintillation decay time and pulse height spectra. When we irradiated X-rays, we observed the scintillation emission at 360 and 460 nm caused by Tm3+ 4f-4f transitions. Under 662 keV γ-ray irradiation, we determined absolute scintillation light yield of 2340 ph/MeV for the 2.0% Tm doped sample. Taking into account whole optical and scintillation properties, 2.0% doping was the best for Tm-doped LPS crystals.

Growth and Scintillation Properties of Directionally Solidified Ce:LaBr3/AEBr2 (AE = Mg, Ca, Sr, Ba) Eutectic System

Ce-doped LaBr3/AEBr2 (AE = Mg, Ca, Sr, Ba) eutectics were grown using the Bridgman–Stockbarger (BS) method in quartz ampoules. The eutectics (AE = Mg and Ca) showed optical transparency like optical fiber bundles. A grown Ce-doped LaBr3/MgBr2 eutectic shows a 355 nm emission ascribed to Ce3+ 4f-5d transition under X-ray excitation. The smaller the ionic size of AE, the higher the light yield of the sample was. The light yield of Ce:LaBr3/MgBr2 was 34,300 photon/MeV, which is higher than Ce:LYSO standard. Scintillation decay time under 662 keV gamma-ray excitation was 18.8 ns.

Luminescence and scintillation properties of Cs2ZnCl4 and Cs3ZnCl5

Fast scintillation materials based on the ternary halide crystals of Cs2ZnCl4 and Cs3ZnCl5 were synthesized. Under X-ray irradiation, an emission band at 310 nm with shoulders at 260 and 410 nm was observed for Cs2ZnCl4, and emission bands at 240, 290, and 390 nm were observed for Cs3ZnCl5. The observed bands were primarily attributable to Auger-free luminescence (AFL). In the temporal scintillation profiles, scintillation decay time constants of 1.7 and 1.1 ns were found for Cs2ZnCl4 and Cs3ZnCl5, respectively. These fast components are attributed to AFL and constituted greater than 88% of the total scintillation amount. On the basis of the pulse height spectra, the light yields of Cs2ZnCl4 and Cs3ZnCl5 were estimated to be 1280 and 440 photons MeV−1, respectively. The light yield of the fast component of Cs2ZnCl4 was slightly lower than that of BaF2, which is a commercially available fast scintillator exhibiting AFL.

Luminescence and Scintillation Properties of Mg2+-Codoped Lu0.6Gd2.4Al2Ga3O12:Ce Single Crystal

The scintillation properties of Mg <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup> -codoped Lu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.6</sub> Gd <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2.4</sub> Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sub> :Ce (LGAGG:Ce,Mg) single crystal grown by Czochralski's method are investigated. The light yield (LY), scintillation decay time, and coincidence time resolution are presented in comparison with a GAGG:Ce,Mg reference crystal. The LY of 26 200 photons/MeV obtained for LGAGG:Ce,Mg is lower than that of 39 600 photons/MeV for GAGG:Ce,Mg. Despite a lower LY value, the time resolution of LGAGG:Ce,Mg is comparable to that of GAGG:Ce,Mg due to its faster scintillation decay time. LGAGG:Ce,Mg exhibits a much faster afterglow decay and a lower thermally stimulated luminescence intensity with respect to GAGG:Ce,Mg.

Performance study of GAGG:Ce scintillator for gamma and neutron detection

Inorganic scintillators with high density and high light output are widely used for the detection of ionizing radiation in high energy physics, space exploration, modern medical imaging and industry. Recently developed cerium-doped Gd3Al2Ga3O12 (GAGG:Ce) crystal is a promising scintillator with high density, high light yield, fast scintillation decay time and non-hygroscopicity used for calorimetry. Furthermore, the presence of Gd isotopes with a very high thermal neutron capture cross section makes the GAGG:Ce crystal efficiently sensitive for neutron detection. In this manuscript, performance of gamma and neutron detection based on GAGG:Ce scintillator has been studied carefully. Scintillation properties of Single crystal and ceramic GAGG:Ce were investigated. Thanks to very high light yield, the photopeaks due to conversion electrons and low energy X-ray are successfully observed and can be used to do the neutron/gamma discrimination.

Scintillation properties of organic–inorganic layered perovskite nanocrystals in glass

We fabricated organic–inorganic perovskite nanocrystals in nanoporous glasses (OIPiG) where (C6H5C2H4NH3)2PbBr4 (Phe) was incorporated into about 4 nm diameter pores and evaluated their photoluminescence and scintillation properties, compared with the Phe single crystal. Both the samples showed emissions due to the recombination of free excitons in the inorganic layer under 280 nm excitation light. In scintillation, a weak and broad scintillation peak possibly due to the free excitons and bound excitons was observed in the OIPiG, while the Phe single crystal showed efficient scintillation due to free exciton emissions with a peak approximately at 435 nm. The scintillation decay time constant (4.4 ns) due to the free excitons for the OIPiG was found to be faster than that (6.6 ns) for the Phe single crystal. In addition, the afterglow levels were confirmed to be 340 ppm for the OIPiG and 20 ppm for the Phe single crystal. The afterglow level of the OIPiG was higher than that of the Phe single crystal but was almost equivalent to that for the commonly used inorganic scintillator CsI:Tl.

Crystal Growth and Scintillation Properties of Carbazole for Neutron Detection

Carbazole crystals were grown using self-seeding vertical Bridgman technique, and the scintillation properties for neutron detection were investigated. Results of powder X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses indicated the single phase of the grown carbazole crystal with orthorhombic structure. Photo- and radio-luminescence measurements were carried out, and maxima of both emission peaks were at 420 nm. The light yield under 5.5-MeV alpha-ray irradiation was estimated to be 1.87 times higher than that of lithium glass GS-20. The scintillation decay time under neutron irradiation was estimated to be 11.4 ± 0.3 ns. It follows from the temperature dependence measurements that the light output under 662-keV gamma-ray excitation decreases with increasing temperature.

TlSr2Cl5: New intrinsically activated crystalline scintillator

We report the luminescence and scintillation properties of TlSr2Cl5 crystals, which have a large effective atomic number (Zeff = 63.7), for application in X-ray and gamma ray detection. TlSr2Cl5 crystals were prepared under vacuum using the self-seeding solidification method. The scintillation emission bands were observed at 430 and 490 nm, which are close to the emission wavelengths of TlMgCl3 and TlCdCl3. The peak wavelengths were characteristic of self-activated thallium-based chloride crystals. The scintillation decay time constants were estimated to be 7.5 ns (61%), 99 ns (7%), and 1375 ns (32%). These decay time constants are close to those of TlMgCl3 and TlCdCl3 and are also characteristic of self-activated thallium-based chloride crystals. The light yield of TlSr2Cl5 was estimated to be approximately 19,000 photons/MeV, which is higher than that of Gd2SiO5(Ce) (GSO) (10,000 photons/MeV) and close to that of Lu2SiO5(Ce) (LSO) (27,000 photons/MeV).

Scintillation Properties of Tetrafluoroaluminate Crystal

In this article, single crystals of a new nonhygroscopic scintillating material of tetrafluoroaluminate (TlAlF4) were grown using the Bridgman–Stockbarger technique. The diffraction pattern obtained from powder X-ray diffraction was found to be in good agreement with the reference data. The X-ray-induced luminescence measurements of the grown crystal sample exhibit a very strong intrinsic emission band in the wavelength range from 300 to 450 nm, with a peak maximum at 390 nm. Scintillation properties, such as pulse height spectra and decay time of the grown crystals, were investigated using $\gamma $ -rays from the 137Cs radiation source. The scintillation light yield was found to be ~11 800 ph/MeV. At room temperature, the measured decay time profile was fitted with three exponential functions; the result showed a fast component of 194 ns (13.1%), a medium component of 992 ns (84.6%), and a slow component of 3.5 $\mu \text{s}$ (2.3%). Trap centers were studied using the results obtained from thermally stimulated luminescence. The temperature dependence of the scintillation light yield and decay time was also studied. The results showed that TlAlF4 is a promising scintillator crystal, and thus, a potential candidate for X-ray and $\gamma $ -ray detection.