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Investigation of the scintillation screens used for low energy DC ion beam profiling
摘要： A ion beam profile monitoring system based on scintillation screens has been established for a neutron generator used for neutron radiography. Three types of scintillation screens (monocrystalline Al2O3, Quartz and BGO) were investigated for their response to the 100 keV, 30 ??A, DC deuterium ion beams. The light yield, beam width, and electric charge accumulation effect of the scintillation materials were tested. The temperature rises of the scintillation screens caused by ion irradiation was calculated. Results showed that, the electric charge accumulation effect is very serious for this type of ion beams, and the using of metal film or mesh on the scintillation screen surface to diminish the electric charging is necessary. Al2O3 screen owns the best behavior of radiation hardness, its measured beam width only shows a little change for the ion irradiation of up to 2.3×1015 particles/mm2. The temperature rises of Al2O3, Quartz and BGO under ion irradiation of 2.3×1015 particles/mm2 was 120 ?C, 243 ?C, and 768 ?C respectively. The temperature rise difference is quite coincident with the light yield degradation of the three material, so temperature might be the key factor that affect the light yield degradation of scintillation materials.
关键词： Beam profile,Radiation effect,Scintillation screen,Low energy ion beam
更新于2025-09-10 09:29:36
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Dynamic 3D measurement of modulated radiotherapy: a scintillator-based approach
摘要： With the rise of high-conformity dynamic radiotherapy, such as volumetric modulated arc therapy and robotic radiosurgery, the temporal dimension of dose measurement is becoming increasingly important. It must be possible to tell both ‘where’ and ‘when’ a discrepancy occurs between the plan and its delivery. A 3D scintillation-based dosimetry system could be ideal for such a thorough, end-to-end verification; however, the challenge lies in retrieving the volumetric information of the light-emitting volume. This paper discusses the motivation, from an optics point of view, of using the images acquired with a plenoptic camera, or light field imager, of an irradiated plastic scintillator volume to reconstruct the delivered 3D dose distribution. Current work focuses on the optimization of the optical design as well as the data processing that is involved in the ongoing development of a clinically viable, second generation dosimetry system.
关键词： dynamic radiotherapy,volumetric modulated arc therapy,plenoptic camera,robotic radiosurgery,3D scintillation-based dosimetry
更新于2025-09-09 09:28:46
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Recent advances in bubble-assisted Liquid Hole-Multipliers in liquid xenon
摘要： We report on recent advances in the operation of bubble-assisted Liquid Hole-Multipliers (LHM). By con?ning a vapor bubble under or adjacent to a perforated electrode immersed in liquid xenon, we could record both radiation-induced ionization electrons and primary scintillation photons in the noble liquid. Four types of LHM electrodes were investigated: a THGEM, standard double-conical GEM, 50 μm-thick single-conical GEM (SC-GEM) and 125 μm-thick SC-GEM — all coated with CsI photocathodes. The 125 μm-thick SC-GEM provided the highest electroluminescence (EL) yields, up to ～ 400 photons per electron over 4π, with an RMS pulse-height resolution reaching 5.5% for events comprising ～ 7000 primary electrons. Applying a high transfer ?eld across the bubble, the EL yield was further increased by a factor of ～ 5. The feasibility of a vertical-mode LHM, with the bubble con?ned between two vertical electrodes, and the operation of a two-stage LHM con?guration were demonstrated for the ?rst time. We combine electrostatic simulations with observed signals to draw conclusions regarding the location of the liquid-gas interface and suggest an explanation for the observed di?erences in EL yield between the investigated electrodes.
关键词： Micropattern gaseous detectors (MSGC, GEM, THGEM, RETHGEM, MHSP, MICROPIC, MICROMEGAS, InGrid, etc),Noble liquid detectors (scintillation, ionization, double-phase),Charge transport, multiplication and electroluminescence in rare gases and liquids
更新于2025-09-09 09:28:46
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O12 scintillator
摘要： The characteristics of a Gd3Al2Ga3O12 crystal scintillator doped with cerium and co-doped with magnesium and titanium have been studied, mainly in view of using it for the Phase II upgrade of the LHCb electromagnetic calorimeter. Samples of the scintillator were irradiated with γ (60Co) to 2 kGy and with 24 GeV protons to 900 kGy. The proton fluence value was ～3·1015 cm?2. It was found that γ-irradiation did not produce any change in the optical transmission of the crystals in the spectral range of the scintillation light, whereas a degradation after the proton irradiation was measurable. For the 1 cm thick sample, a loss of transmission of 3.6% was measured at the wavelength of maximum scintillation (520 nm), and the measured induced absorption coefficient at this wavelength was ～3.6 m?1. The formation of radioisotopes in the crystal at proton irradiation has been analyzed. The formation of isotopes was also simulated with the help of the FLUKA package. The simulation was found to be in a good agreement with experimental results. The results have been used to estimate the expected intensity of parasitic radio-luminescence at high-luminosity operation in a GAGG/W sampling electromagnetic calorimeter.
关键词： Electromagnetic calorimetry,radiation damage,gadolinium-aluminum-gallium garnet,optical transmission,scintillation crystal
更新于2025-09-09 09:28:46
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Effect of Anisotropy on Ionospheric Scintillations Observed by Synthetic Aperture Radar (Sar)
摘要： Spaced-based synthetic aperture radar (SAR) operating at low frequencies and capable of earth observation are affected by the layer of ionosphere. The interaction of the signal with the irregularity layer degrades and distorts the SAR image quality. The accurate assumption of size of the irregularities, defined by the axial ratio, in determining the effects of scintillation on the signal is critical. In the present work, the authors have compared the impact of different axial ratios on a pair of SAR images over the Indian subcontinent to estimate scintillation and ionospheric parameters. The parameters are then compared with the available ground-based measurements to determine the precise size of irregularity structure. The amplitude scintillation index, S4, estimated from the Global Positioning Satellite (GPS) receivers for two Indian stations of Tirunelveli and Rajkot are used in this study. The assumption of axial ratio value is 60:1 to estimate the parameters was found to correctly fit into the model.
关键词： SAR,ALOS-2/PALSAR-2,axial ratio,S4,CkL,scintillation
更新于2025-09-09 09:28:46
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[IEEE 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) - Atlanta, GA (2017.10.21-2017.10.28)] 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) - Design of a 2-Bit Sigma-Delta Modulator for Scintillation Waveform Capture
摘要： Sigma-delta modulation is a common technique used in analog-to-digital conversion. It has been shown that it can be implemented in a field-programmable gate array (FPGA) using minimal external analog components. Zhao et al. demonstrated that energy of scintillation pulses can be computed by adding up all the elements on the output from a conventional 1-bit sigma-delta modulator. However, for parameters selected for a suitable resolution and dynamic range, the system passes through a period of saturation. During saturation, information about the shape of the pulse is lost even though the integrated energy remains preserved. We present the design of a 2-bit version of the sigma-delta modulator that makes use of a nonlinear adaptive digital-to-analog converter (DAC) that keeps the system unsaturated. Each output bit is scaled by one of the four possible values the DAC can take, resulting in a 2-bit modulation. We have demonstrated that the 2-bit modulation retains information about the pulse shape.
关键词： Sigma-delta modulation,analog-to-digital conversion,FPGA,scintillation waveform capture,digital-to-analog converter
更新于2025-09-09 09:28:46
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The luminescent properties comparison of RE2O3:Eu(RE=Lu,Y,Sc) with high and low Eu doping concentrations
摘要： Single crystal scintillators of RE2O3:Eu(RE=Lu, Y, Sc) with high (8%) and low (1%) Eu doping concentration were grown by the optical floating zone method. The luminescence and scintillation properties have been investigated and compared thoroughly. Correlated measurements of afterglow curves, photoluminescence excitation and photoluminescence, photoluminescence decay curves and X-ray excitation curves were performed. Lu2O3:Eu and Y2O3:Eu present significant afterglow intensity decreasing after high Eu concentration doping. While for the Sc2O3:Eu, its afterglow intensity even increases slightly. The luminescence efficiencies of high doping concentration samples are weaker than that of the low concentration ones due to the concentration quenching. The integrated X-ray excitation luminescence reveals the scintillation luminescence efficiencies of samples with the high concentration or the low one both have the following sequence:Lu2O3:Eu＞Y2O3:Eu＞Sc2O3:Eu.
关键词： europium-doped sesquioxide,floating zone method,scintillation properties,afterglow,single crystal
更新于2025-09-09 09:28:46
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Effect of CsI(Tl) micro-conical-frustums on the performance of the pixelated CsI(Tl) scintillation screen in X-ray imaging
摘要： The pixelated CsI(Tl) scintillation screen based on oxidized silicon micro-pore array template with CsI(Tl) micro-conical-frustums (CMCF) was proposed. The effect of the CMCF on the performance of the pixelated CsI(Tl) scintillation screen in X-ray imaging was studied by using Geant4 Monte Carlo simulation code. The variations of the light output (LO), modulation transfer function (MTF) and detective quantum efficiency (DQE) for the screen with the cone angle β of the CMCF in X-ray imaging were revealed. The results show that the LO of the pixelated scintillation screen with CMCF is superior to that of the screens with CsI(Tl) micro-cylinders (CMC) or with reversed CsI(Tl) micro-conical-frustums (RCMCF), but the spatial resolution of the X-ray imaging system by using the pixelated scintillation screen with RCMCF is better than that by using the screens with CMCF or with CMC. At low frequency, the cone angle β corresponding to DQEs from good to bad are 2.40°, 0.00° and -2.40°. But at high frequency, the cone angle β corresponding to DQEs from good to bad change to 2.40°, -2.40° and 0.00°. The reason is that, for a pixelated scintillation screen, the DQE for the screen not only depends on the efficiency of X-ray absorption, but also depends on the number of scintillation photons exiting the bottom the screen per interacting X-ray photon and its Poisson excess, and MTF. The simulated results of DQEs show that the comprehensive performance of the pixelated CsI(Tl) screen with CMCF in X-ray imaging is better than that of the screens with CMC or with CRMCF.
关键词： Shape of CsI(Tl) micro-conical-frustum,Performance in X-ray imaging,Oxidized silicon micro-pore array template,Pixelated CsI(Tl) scintillation screen
更新于2025-09-09 09:28:46
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A First Response Microcontroller Based Digital Radiation Survey Meter Using Scintillation Detector
摘要： This paper presents the microcontroller based advanced technique to design and development of a portable radiation survey meter to measure low level gamma radiation using NAI(T1) scintillation detector. A scintillation detector was used as radiation detector and a microcontroller PIC16F876 was used to control the function of the developed system. The microcontroller generated square wave frequency at specified pulse width to produce high voltage (+1200V) and regulates it. The high voltage was required to activate the scintillation detector. Preamplifier and amplifier were designed to make the detector signal for the further amplification. Microcontroller senses the pulses from the amplifier output and processes data by software and displays the results. The microcontroller was programmed using a high level programming language ‘C’ with PCWH compiler.
关键词： PIC16F876,Digital and Portable,Scintillation detector,PCWH,NaI (T1),Gamma ray
更新于2025-09-09 09:28:46
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[IEEE 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) - Atlanta, GA, USA (2017.10.21-2017.10.28)] 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) - Rapid Kalman-Filter stabilization technique for single- and multi-detector systems
摘要： Most spectroscopic applications, especially homeland security relevant equipment relies on well-calibrated spectral data. A Kalman filter is applied to the known problem of stabilization, which means online calibration of a scintillation detector to a predefined reference peak. The method uses stochastic assumptions on the measurement uncertainties and an iterative update with new measurements. Introducing prior knowledge about the stochastic and continuously resupplying new spectral data to the filter enhances the predicted gain correction value and allows a rapid determination of this value. In multi-detector setups, the spectral alignment of data from all detectors is mandatory for performing data fusion or any further evaluations. The described Kalman technique also allows to perform this rapid cross-detector synchronization online, leading to matched up spectra at acquisition time.
关键词： multi-detector systems,stabilization,Kalman filter,scintillation detector,spectral alignment
更新于2025-09-09 09:28:46