Eu Scintillator Research Articles

Neutron moderation and manufacturing viability of 3D printed Acrylonitrile Butadiene Styrene spheres for use in neutron radiation detectors

Neutron moderation characteristics and manufacturing viability of ABS (Acrylonitrile Butadiene Styrene) spheres were studied using a 6LiI(Eu) scintillator detector and a commercial 3D printer with FDM-type extruder. Response functions (RFs) for the detector with ABS spheres of varying diameters were calculated with the Monte Carlo (MC) code MCNPX and compared with RFs obtained for high-density polyethylene (HDPE) spheres. Designed ABS spheres were produced and irradiated with 241Am–Be neutron beams to validate MC simulations.

Compact and versatile neutron imaging detector with sub-4μm spatial resolution based on a single-crystal thin-film scintillator.

A large and increasing number of scientific domains pushes for high neutron imaging resolution achieved in reasonable times. Here we present the principle, design and performance of a detector based on infinity corrected optics combined with a crystalline Gd3Ga5O12 : Eu scintillator, which provides an isotropic sub-4 µm true resolution. The exposure times are only of a few minutes per image. This is made possible also by the uniquely intense cold neutron flux available at the imaging beamline NeXT-Grenoble. These comparatively rapid acquisitions are compatible with multiple high quality tomographic acquisitions, opening new venues for in-operando testing, as briefly exemplified here.

Single Crystal Preparation and Luminescent Properties of Lu2O3:Eu Scintillator by Vertical Bridgman Method

AbstractEuropium‐doped lutetium oxide (Lu2O3:Eu) single crystal is grown by vertical Bridgman method for the first time. Correlated measurements of X‐ray diffraction, X‐ray fluorescence spectra, optical transmittance, photoluminescence excitation, photoluminescence (PL), PL decay, and X‐ray excited luminescence (XEL) spectra are performed. The transmittance of about 80% above 300 nm indicates that the crystal is of good optical quality. By measuring actual Eu3+ concentration, the effective segregation coefficient of Eu3+ in the Lu2O3:Eu crystal is calculated to be 0.75. In the PL spectrum, the dominant emission peaks at 612 and 630 nm originate from the 5D0→7F2 transitions of Eu3+ in C2 site. It is worth mentioning that several emission peaks between 575 and 605 nm mainly ascribe to the transitions of different 5D0 levels to the split 7F1 levels of Eu(C2) or Eu(C3i). PL decay spectra indicate the decay time of 612 nm emission can be determined about 1.0 ms. The decay curve of 582.6 nm emission can be fitted into triple components, and the 5.3 and 1.4 ms components are attributed to Eu3+(C3i) and Eu3+(C2), respectively. The XEL strongest emission of Lu2O3:Eu sample is around 612 nm with a bright red luminescence that matches silicon photodetectors sensitivity.

A PIPS + SrI2(Eu) detector for atmospheric radioxenon monitoring

The PIPS–SrI2(Eu) is a prototype atmospheric radioxenon detection system designed at Oregon State University in support of international efforts towards monitoring clandestine nuclear weapon testing activities. This detector aims to address some shortcomings found in currently deployed beta–gamma atmospheric radioxenon detection systems, such as lackluster energy resolution and memory effect, by employing modern detection materials and readout. The system uses a PIPSBox, a silicon-based gas cell, for electron detection, and a pair of ultrabright, D-shaped SrI2(Eu) scintillators coupled to silicon photomultipliers for photon detection. A custom eight-channel digital pulse processor equipped with a field programmable gate-array (FPGA) identifies electron–photon coincidences between the volumes in near real-time. Gas samples of the four radioxenon isotopes of interest were independently measured with the PIPS–SrI2(Eu) detection system to determine energy resolution and efficiency. Application of FPGA-based coincidence discrimination in near real-time reduced the ambient background count rate by 95.85 ± 0.04%. Using parameters from the Xenon International gas processing unit and assuming a blank sample and zero memory effect the minimum detectable concentrations (MDCs) for the isotopes were calculated to be 0.12 ± 0.03, 0.27 ± 0.05, 0.15 ± 0.02, and 1.00 ± 0.08 mBq/m3 air for 131mXe, 133Xe, 133mXe, and 135Xe, respectively. These MDC estimates compare well with other radioxenon detection systems employed in the International Monitoring System (IMS) and indicate that the PIPS–SrI2(Eu) is in compliance with the Comprehensive Nuclear Test-Ban-Treaty Organization (CTBTO) sensitivity requirement of ≤1 mBq/m3 for 133Xe.

A novel experimental system for the KDK measurement of the 40K decay scheme relevant for rare event searches

Potassium-40 (40K) is a long-lived, naturally occurring radioactive isotope. The decay products are prominent backgrounds for many rare event searches, including those involving NaI-based scintillators. 40K also plays a role in geochronological dating techniques. The branching ratio of the electron capture directly to the ground state of 40Ar has never been measured, which can cause difficulty in interpreting certain results or can lead to lack of precision depending on the field and analysis technique. The KDK (Potassium (K) Decay (DK)) collaboration is measuring this decay. A composite method has a silicon drift detector with an enriched, thermally deposited 40K source inside the Modular Total Absorption Spectrometer. This setup has been characterized in terms of energy calibration, gamma tagging efficiency, live time and false negatives and positives. A complementary, homogeneous, method is also discussed; it employs a KSr2I5:Eu scintillator as source and detector.

A multi-moderator neutron spectrometer for use in BNCT studies of the Tehran research reactor

The Tehran Research Reactor is the only appropriate and available neutron source in Iran for clinical boron neutron capture therapy (BNCT). One of the requirements for BNCT is to carefully evaluate and measure the therapeutic neutron beam (epithermal neutrons) as well as the fast and thermal neutron components for successful treatment. In this research, a multi-moderator neutron spectrometer (MMNS) with LiI(Eu) scintillator as neutron counter was proposed for these measurements in the range of 10−11 eV to 15 MeV. The results confirmed promising precision of the designed MMNS for the epithermal spectrum; however, the angular dependency of the therapeutic beam due to any probable change in the beam-shaping assembly should be considered.

Preparation, luminescent properties and X-ray imaging result of Lu2O3:Eu structured scintillation film on sapphire substrate by LCVD method

Lu2O3:Eu scintillation film is one of the most attractive candidate for the hard X-ray imaging, especially for sub-micrometer spatial resolution X-ray detectors. This study was focused on the preparation and characterization of Lu2O3:Eu structured scintillation film on (001) sapphire substrate by laser chemical vapor deposition (LCVD). The grazing incidence X-ray diffraction (GIXRD) measurement shows that the film with thicknesses of 3 μm is oriented along the (411) direction. The morphology and luminescent properties, including photoluminescence excitation (PLE), photoluminescence (PL) and PL decay, were measured and discussed. The sub-micrometer spatial resolution was obtained at BL13W1 station at Shanghai synchrotron radiation facility (SSRF).

Analysis by Monte Carlo methods of the response of an extended-range Bonner Sphere Spectrometer

High-energy neutrons up to 230 MeV are generated as a consequence of (p,n) nuclear reactions in proton therapy facilities. The aim of this work is to evaluate the potential extension of the UPM Bonner Sphere Spectrometer (BSS) through the use of spallation materials, for its future application to determine neutron fluence spectra in such facilities. Monte Carlo methods have been used to model the response of the actual and modified spheres with the introduction of a spallation material layer, lead or copper, analyzing their response functions. An analysis is also made of the neutron fluence spectra over the 6LiI(Eu) scintillator volume and the uncertainty that can be associated to the response functions at high energies as a consequence of the different physics models that can be applied for their analysis.

Gamma-ray spectroscopic characterization of long, rapidly-grown KSr2I5:Eu crystals

Collimation and volumetric studies were done to evaluate the gamma-ray spectroscopic performance of KSr2I5:Eu scintillators grown via the vertical Bridgman method. To demonstrate practical crystal growth for large-scale production, Ø1 in. × 6 in. long crystals were grown using fast pulling rates up to 5 mm/h and short cooling times. The long crystals were sectioned into shorter Ø1 in. cylinders to investigate sample-to-sample variation of scintillation properties, the effects of self-absorption and scintillation non-uniformity using different gamma-ray excitation configurations. The best light output and energy resolution achieved for the largest volume and aspect ratio crystals (60 cm3 or Ø1 in × 4.7 in. long) were 53,500 ph/MeV and 4.6% at 662 keV. Finally, we produced eight Ø1 in. × 1 in. (12.5 cm3) cylindrical samples, four from each boule, with energy resolutions between 3.1%-3.5% at 662 keV.

MC Simulates the Detection Efficiency of Different Sizes of BaClBr(Eu)

The performance of a new BaClBr(Eu) scintillator discovered in recent years was studied. The photon yield and detection efficiency of different sizes of the theoretical model of the BaClBr(Eu) detector were calculated by the MCNP program, and compared with the traditional NaCl(Tl) detector. Studies have found that the detection efficiency of the scintillator detector increases as the size of the scintillator increases. When the γ-ray energy is 662 KeV, the photon yield of the BaClBr(Eu) detector is lower than that of the NaCl(Tl) detector, and the light yield difference is 6.21% - 3.15%. The detection efficiency of BaClBr(Eu) scintillator is higher than that of NaCl(Tl) scintillator, and the relative efficiency is 11.7% - 22.52%. Simulating the effect of different ray energy on the photon yield and detection efficiency of the scintillator under the same crystal size, it is found that the photon yield of the BaClBr(Eu) scintillator is between the NaCl(Tl) and CsI(Tl) scintillator detectors. The detection efficiency of low-energy rays is close to that of NaCl(Tl), and the detection efficiency of high-energy rays is much higher than that of NaCl(Tl). The detection efficiency of the high and low ray energy range is close to that of the CsI(Tl) detector.

Single crystal growth and luminescent properties of YSH:Eu scintillator by optical floating zone method

Single crystal of europium doped yttria stabilized hafnia (YSH) was grown by optical floating zone method. The structure of as grown sample was determined through X-ray diffraction. Its transmission spectrum was recorded. Its photoluminescence (PL) and scintillation properties, including PL, PL decay, scintillation luminescence efficiency and afterglow level, were measured and compared with another heavy scintillator Lu2O3:Eu. The reasons for the PL and scintillation difference between YSH:Eu and Lu2O3:Eu were discussed in this paper.

Construction and Characterization of a Novel Single Pixel Beta Detector for Intraoperative Guidance in Breast-Conserving Surgery

Breast-conserving surgery is imprecise requiring re-excision in up to 40% of cases. One potential method of improving breast-conserving surgery accuracy is to use a beta particle detector to evaluate the surface of the excised tissue for any cancerous deposits, intraoperatively. Patients could be injected with a radiopharmaceutical that emits beta particles and preferentially accumulates within cancer cells. Cancer cells found on the surface of the excised tissue indicate that the surgery is incomplete. The purpose of this paper is to develop and analyze a novel single pixel beta sensitive detector. The detector is made up of a calcium fluoride europium doped [CaF2(Eu)] scintillation crystal, which is coupled to a silicon photomultiplier. A computational model of the detector response was derived from an empirically generated, 2-D, detector sensitivity map. This study determined that a CaF2(Eu) scintillator of 0.5-mm thickness provided superior beta to gamma detection ratio. According to the detector response, it is expected that with an acquisition time of 30 s, the tumor-to-background ratio of 5 or higher, and a normal breast tissue activity of 1.69 kBq/ml, less than 1 mm2 tumor detection is achievable. The result of this paper indicates that the radio-guided surgery with a CaF2(Eu) scintillation detector could be feasible to intraoperatively assess tumor margin involvement.

Development and Characterization of a Phoswich Radiation Sensor to Simultaneously Measure the Count Rates and Energies of Beta and Gamma Radiation

In this research, we developed and characterized a phoswich radiation sensor (PHORS) to simultaneously measure the count rates and the energies of beta and gamma radiation. The proposed PHORS device comprises a sensing probe combining NaI(Tl) and CaF2(Eu) scintillators for simultaneous measurement of beta and gamma radiation, a multichannel analyzer to characterize the radiation energy, and a laptop computer for signal analysis. For its performance test, we employed a prototype PHORS to measure the energies and the count rates of beta and gamma radiation from three different radiation sources for separation distances from 2 to 10 cm. The count rates of the PHORS were consistent with expected rates, and the captured energy spectra showed classic radionuclide characteristics. Thus, the proposed PHORS system provides an effective and facile tool to detect beta and gamma radiation simultaneously and to identify radionuclides from the captured energy spectra.

Crystal growth and characterization of high performance KSr2BrxI5−x:Eu scintillators

In this work we investigated the effects of replacing some of the matrix iodine atoms in KSr2I5:Eu with bromine, forming new solid solutions of KSr2BrxI(5−x):Eu (where 0.05 ≤ x ≤ 1). Transparent 15 and 22 mm diameter single crystals of KSr2BrxI(5−x):Eu were grown via the vertical Bridgman technique using a two-zone transparent furnace. The scintillation properties of the mixed compounds were investigated and compared to the non-mixed parent compound, KSr2I5:Eu. The addition of bromine blue-shifted the x-ray excited emission from 450 to 446 nm, increased the light yield by ~11% and decreased the scintillation decay time by suppressing its secondary component (≥3 µs), while maintaining energy resolutions comparable to the reference crystal. Thermoluminescence glow curves showed that the addition of bromine modified the shallow traps located between 25 and 55 K, suggesting that these traps are responsible for lengthening KSI’s decay time. In large sizes (10.3 cm3), KSr2Br0.10I4.90:Eu 2% had light yields up to 79,000 ph/MeV and energy resolutions as low as 3.2% at 662 keV.

QUANTIFICATION OF THE KAERI'S MOVABLE NEUTRON IRRADIATOR BY USING A 6LiI(Eu) SCINTILLATOR.

There is no standardised on-site calibration system for performance testing and calibration of neutron area monitors although there is a mobile irradiation device as like a neutron howitzer. For this reason, neutron area monitors, which legally and periodically require calibration in Korea, are removed from the installation location and tested at the Korea Atomic Energy Research Institute (KAERI) or the Korea Research Institute of Standards and Science (KRISS). To test the possibility of an on-site performance calibration system, the KAERI manufactured a movable neutron irradiator. The movable neutron irradiator is composed of high-density polyethylene and has an overall size of 50 cm (L) × 50 cm (W) × 46 cm (H). In this study, the neutron fields generated by the movable neutron irradiator were quantified at distances of 80, 100, 120, and 140 cm from the centre of the source. Quantification was performed using the initially estimated neutron spectrum from the computer simulation, the count rate data measured using a 6LiI(Eu) scintillator combined with a Bonner sphere spectrometer (BSS), and the response function of the BSS. As a result of the quantification of the neutron field at each distance, the fractions of scattered neutrons to total neutron fluence were almost constant within 5%.

An active Bonner sphere spectrometer for intense neutron fields

Abstract Neutron producing installations can be characterized by the presence of intense pulsed fields, possibly accompanied by large photon background. This is the case of particle accelerators and, more recently, laser-based radiation sources. Determining neutron spectra in these fields is particularly complex, as active detectors may likely be affected by dead-time and saturation effects, and their parasitic response to photons is generally non zero. Passive Bonner Spheres Spectrometers (BSS) equipped with activation foils have been used in these cases. Owing on a new type of active thermal neutron detector (TNRD, Thermal Neutron Rate Detector), this work presents a BSS able to operate in intense, pulsed fields, with large photon background. The response matrix of this spectrometer was experimentally verified by comparison with a well-established BSS based on a 11 mm (diameter) × 3 mm (thickness) 6 LiI(Eu) scintillator . The comparison was performed in the 14 MeV and 2.9 MeV neutron fields produced at the Frascati Neutron Generator. The proposed spectrometer can constitute a valuable tool for operational neutron dosimetry .

Laser chemical vapor deposition of Lu2O3:Eu scintillation film

Lu2O3:Eu scintillation film is one of the most attractive candidate for the hard x-ray imaging, especially above 20 keV. A micro-columnar film with 10 μm thickness of Lu2O3:Eu was firstly obtained by laser chemical vapor deposition on not-oriented Lu2O3 single crystal substrate. The morphology of obtained film was investigated by the scanning electron microscopy. The photoluminescence and scintillation properties were measured and discussed, including photoluminescence excitation and photoluminescence curves, photoluminescence decay curves, and x-ray excited luminescence curve.

LCVD preparation and luminescence properties of Lu2O3:Eu single crystal film

Lu2O3:Eu scintillation film is one of the most attractive candidate for the hard X-ray imaging, especially in the range of above 30 keV. Single crystal film (SCF) of Lu2O3:Eu is difficult to obtain due to its super high melting point. In this letter, transparent Lu2O3:Eu SCF with 2.5 μm thickness was firstly obtained by laser chemical vapor deposition on a YSZ (100) single crystal substrate. The crystallinity and morphology of obtained film were investigated by the scan electron microscopy and X-ray diffraction. The photoluminescence and scintillation properties were measured and discussed, including photoluminescence excitation and photoluminescence curves, photoluminescence decay curves, X-ray excited luminescence curve and afterglow curve.

Development of a simultaneous evaluation method of radioactivity in soil and dose rate using CeBr3 and SrI2(Eu) scintillation detectors for environmental monitoring

Development of a simultaneous evaluation method of radioactivity in soil and dose rate using CeBr3 and SrI2(Eu) scintillation detectors for environmental monitoring

Application of a SrI2(Eu) scintillation detector to in situ gamma-ray spectrometry in the environment

Using scintillation detectors to spectrometrically determine dose rate is useful in response to a nuclear accident, because the nuclide contribution in the measured dose rate can be determined. However, to select an appropriate scintillator for in situ gamma-ray spectrometry in the environment, energy resolution and counting efficiency should be evaluated. A SrI2(Eu) crystal is one of the promising scintillators, with good energy resolution and light output performance. But its long scintillation decay time of about 1 μs needs to be well matched with the signal processing unit of the gamma-ray spectrometer to avoid degrading its good performance. In this study a performance test was first conducted to determine the optimized pulse shaping time in the gamma-ray detection process. In addition, a Monte Carlo simulation of the SrI2(Eu) detector was performed to establish the algorithm for the spectrometric determination of dose rate. Finally, in situ gamma-ray spectrometry was performed with the SrI2(Eu) detector to determine the ambient dose rate, as well as the dose rate of nuclides in the environment. The results were successfully compared with those of HPIC (high pressure ion chamber), portable HPGe (high purity Ge), and NaI(Tl) detectors at the same site.