This study presents the design and performance results for compact plastic scintillator strips using a wavelength shifting fiber(WLS-fiber)readout with dimensions of 0.1 m×0.02 m×2 m.This approach was evalua...This study presents the design and performance results for compact plastic scintillator strips using a wavelength shifting fiber(WLS-fiber)readout with dimensions of 0.1 m×0.02 m×2 m.This approach was evaluated as a candidate for a cosmic-ray muon detector for the Taishan Antineutrino Observatory(JUNO-TAO).The strips coupled with 3-inch photomultiplier tubes(PMTs)were measured and compared between the single-end and double-end readout options.Additionally,a strip using the double-end option coupling with a silicon photomultiplier(SiPM)was further evaluated and compared with the results obtained using PMTs.The performance of the strips was determined by a detailed survey along their length with a cosmicray muon after detailed characterization of the 3-inch PMTs and SiPMs.The proposed design employing a compact plastic scintillator strip with WLS-fiber coupling to a SiPM provides a good choice for cosmic-ray muon veto detectors,particularly when detector dimensions must be limited.展开更多
Plastic scintillators(PSs)embedded with wavelength-shifting fibers are widely used in high-energy particle physics,such as in muon taggers,as well as in medical physics and other applications.In this study,a simulatio...Plastic scintillators(PSs)embedded with wavelength-shifting fibers are widely used in high-energy particle physics,such as in muon taggers,as well as in medical physics and other applications.In this study,a simulation package was built to evaluate the effects of the diameter and layout of optical fibers on the light yield with different configurations.The optimal optical configuration was designed based on simulations and validated using two PS prototypes under certain experimental condi-tions.A top veto tracker(TVT)for the JUNO-TAO experiment,comprising four layers of 160 strips of PS,was designed and evaluated.The threshold was evaluated when the muon tagging efficiency of a PS strip was>99%.The efficiency of three layer out of four layer of TVT is>99%,even with a tagging efficiency of a single strip as low as 97%,using a threshold of 10 photoelectrons and assuming a 40%silicon PM photon detection efficiency.展开更多
To reduce the experimental uncertainty in the 235 U resonance energy region and improve the detection efficiency for neutron total cross section measurements compared with those obtained with the neutron total cross s...To reduce the experimental uncertainty in the 235 U resonance energy region and improve the detection efficiency for neutron total cross section measurements compared with those obtained with the neutron total cross section spectrometer(NTOX), a dedicated lithium-containing scintillation detector has been developed on the Back-n beam line at the China Spallation Neutron Source. The Fast Scintillator-based Neutron Total Cross Section(FAST) spectrometer has been designed based on a Cs2Li La Br6(CLLB) scintillator considering the γ-ray flash and neutron environment on the Back-n beam line. The response of the CLLB scintillator to neutrons and γ-rays was evaluated with different 6Li/7 Li abundance ratios using Geant4. The neutron-γdiscrimination performance of the CLLB has been simulated considering different scintillation parameters, physical designs,and light readout modes. A cubic 6Li-enriched( > 90%) CLLB scintillator, which has a thickness of 4-9 mm and side length of no less than 50 mm to cover the Φ 50 mm neutron beam at the spectrometer position, has been proposed coupling to a side readout SiPM array to construct the FAST spectrometer. The developed simulation techniques for neutron-γ discrimination performance could provide technical support for other neutron-induced reaction measurements on the Back-n beam line.展开更多
High-precision vertex and energy reconstruction are crucial for large liquid scintillator detectors such as that at the Jiangmen Underground Neutrino Observatory(JUNO),especially for the determination of neutrino mass...High-precision vertex and energy reconstruction are crucial for large liquid scintillator detectors such as that at the Jiangmen Underground Neutrino Observatory(JUNO),especially for the determination of neutrino mass ordering by analyzing the energy spectrum of reactor neutrinos.This paper presents a data-driven method to obtain a more realistic and accurate expected PMT response of positron events in JUNO and develops a simultaneous vertex and energy reconstruction method that combines the charge and time information of PMTs.For the JUNO detector,the impact of the vertex inaccuracy on the energy resolution is approximately 0.6%.展开更多
Chinese Spallation Neutron Source(CSNS) has successfully produced its first neutron beam in 28th August 2017. It has been running steadily from March, 2018. According to the construction plan, the engineering material...Chinese Spallation Neutron Source(CSNS) has successfully produced its first neutron beam in 28th August 2017. It has been running steadily from March, 2018. According to the construction plan, the engineering materials diffractometer(EMD) will be installed between 2019–2023. This instrument requires the neutron detectors with the cover area near3 m2in two 90° neutron diffraction angle positions, the neutron detecting efficiency is better than 40%@1A, and the spatial resolution is better than 4 mm×200 mm in horizontal and vertical directions respectively. We have developed a onedimensional position-sensitive neutron detector based on the oblique6Li F/Zn S(Ag) scintillators, wavelength shifting fibers,and Si PMs(silicon photomultipliers) readout. The inhomogeneity of the neutron detection efficiency between each pixel and each detector module, which caused by the inconsistency of the wave-length shifting fibers in collecting scintillation photons, needs to be mitigated before the installation. A performance optimization experiment of the detector modules was carried out on the BL20(beam line 20) of CSNS. Using water sample, the neutron beam with Φ5 mm exit hole was dispersed related evenly into the forward space. According to the neutron counts of each pixel of the detector module, the readout electronics threshold of each pixel is adjusted. Compared with the unadjusted detector module, the inhomogeneity of the detection efficiency for the adjusted one has been improved from 69% to 90%. The test result of the diffraction peak of the standard sample Si showed that the adjusted detector module works well.展开更多
The synthesis of cerium-doped lutetium oxyorthosilicate (LSO) polycrystalline powders was investigated by a hydrothermal proc-ess. The precursor was obtained by the hydrothermal reaction of Lu(NO3)3 with Na2SiO3 at 2...The synthesis of cerium-doped lutetium oxyorthosilicate (LSO) polycrystalline powders was investigated by a hydrothermal proc-ess. The precursor was obtained by the hydrothermal reaction of Lu(NO3)3 with Na2SiO3 at 200 ℃ for 10 h by using urea as precipitator, fol-lowed by a calcination uader proper temperatures. The results of XRD indicated that the precursor was crystallized into A-type LSO phase at 1000 ℃, and transfetrred to B-type LSO phase when temperature was raised above 1050 ℃. After being heated at 1250 ℃ for 2 h, single phase of B-type LSO powder was synthesized with homogeneous distribution of particle size ranging from 200 to 300 nm. The photolumi-nescence spectrum of as-synthesized LSO: Ce powders showed a typical broad emission peak centered at 404 nm, corresponding to the 5d1-4f transition of Ce3+.展开更多
Large-volume liquid scintillator detectors with ultra-low background levels have been widely used to study neutrino physics and search for dark matter.Event vertex and event time are not only useful for event selectio...Large-volume liquid scintillator detectors with ultra-low background levels have been widely used to study neutrino physics and search for dark matter.Event vertex and event time are not only useful for event selection but also essential for the reconstruction of event energy.In this study,four event vertex and event time reconstruction algorithms using charge and time information collected by photomultiplier tubes were analyzed comprehensively.The effects of photomultiplier tube properties were also investigated.The results indicate that the transit time spread is the main effect degrading the vertex reconstruction,while the effect of dark noise is limited.In addition,when the event is close to the detector boundary,the charge information provides better performance for vertex reconstruction than the time information.展开更多
Daya Bay reactor anti-neutrino experiment is designed to measure an important parameter, θ13, of neutrino by using anti-neutrino created by Daya Bay and Ling Ao nuclear power plants. The experiment need 200 tonnes ga...Daya Bay reactor anti-neutrino experiment is designed to measure an important parameter, θ13, of neutrino by using anti-neutrino created by Daya Bay and Ling Ao nuclear power plants. The experiment need 200 tonnes gadolinium loaded liquid scintillator (Gd-LS) as target. The purpose of this research is to develop suitable Gd-LS candidates for this experiment, which should have long attenuation length, high light yield, long term stability, and should be compatible with the material used to build the containers. Two kinds of Gd-LS were developed using carboxylic acids 2-ethylhexanoic acid (EHA) and 3, 5, 5-trimethylhexanoic acid (TMHA) as complexing ligands and mesitylene and linear alkyl benzene (LAB) as scintillator solvents. Four Gd-LS samples with different Gd content and complexing ligands were prepared and characterized. The relative light yields and the stabilities of all samples are satisfying, and the values of attenuation length show that TMHA is a better ligand than EHA.展开更多
Ce （3+） doped Y3Al5O12 （Ce （3+）∶YAG） single crystal is an good scintillator due to its excellent thermal,mechanic and scintillant performances. In this paper,its vacuum ultraviolet and fluorescence spectra usin...Ce （3+） doped Y3Al5O12 （Ce （3+）∶YAG） single crystal is an good scintillator due to its excellent thermal,mechanic and scintillant performances. In this paper,its vacuum ultraviolet and fluorescence spectra using the synchrotron radiation as the excitation source was studied. The ultraviolet-visible excitation and absorption spectra of Ce （3+）∶YAG were also measured. The excitation energy transfer process and the luminescent differences under direct excitation into the 5d bands of Ce （3+） and excitation of valence band in Ce （3+）∶YAG scintillator were studied.展开更多
The precise vertex reconstruction for large liquid scintillator detectors is essential.A novel machine learning-based method was successfully developed to reconstruct an event vertex in JUNO.In this study,the performa...The precise vertex reconstruction for large liquid scintillator detectors is essential.A novel machine learning-based method was successfully developed to reconstruct an event vertex in JUNO.In this study,the performance of machine learning-based vertex reconstruction was further improved by optimizing the input images of neural networks.By separating the information of different types of PMTs and adding the information of the second hit of PMTs,the vertex resolution was improved by approximately 9.4% at 1 MeV and 9.8% at 11 MeV.展开更多
Fast beam range measurements are required to maximize the time available for patient treatment, given that the beam range requires verification with respect to quality assurance to maintain accelerator commissioning s...Fast beam range measurements are required to maximize the time available for patient treatment, given that the beam range requires verification with respect to quality assurance to maintain accelerator commissioning standards and ensure patient safety. A novel beam range monitor based on a plastic scintillator and multi-pixel photon counter (MPPC) arrays is therefore proposed in this paper. The monitor was constructed using 128 plastic scintillator films with a thickness of 1 mm and an active area of 50 × 50 mm^(2). A customized MPPC array read the scintillation light of each film. The advantage of dividing the active detector volume into films is that it intercepts the particle beam and enables direct differential light yield measurement in each film, in addition to depth-light curve generation without the need for image analysis A GEANT4 simulation, including scintillator quenching effects, was implemented, and the results revealed that Birks’ law exhibited a slight little influence on the position of the beam range, only changing the shape and absolute normalization of the Bragg curve, which is appropriate for the calculation of the beam range using the depth-light curve. The performance of the monitor was evaluated using a heavy-ion medical machine in Wuwei City, Gansu Province, China. The beam range measurement accuracy of the monitor was 1 mm, and the maximum difference between the measured and reference ranges was less than0.2%, thus indicating that the monitor can meet clinica carbon ion therapy requirements.展开更多
The DArk Matter Particle Explorer(DAMPE) is a space-borne apparatus for detecting the highenergy cosmic-ray-like electrons, γ-rays, protons and heavy ions. The Plastic Scintillator Detector(PSD)is the top-most sub-de...The DArk Matter Particle Explorer(DAMPE) is a space-borne apparatus for detecting the highenergy cosmic-ray-like electrons, γ-rays, protons and heavy ions. The Plastic Scintillator Detector(PSD)is the top-most sub-detector of the DAMPE. The PSD is designed to measure the charge of incident highenergy particles and it also serves as a veto detector for discriminating γ-rays from charged particles. In this paper, a PSD on-orbit calibration procedure is described, which includes the five steps of pedestal, dynode correlation, response to minimum-ionizing particles, light attenuation function and energy reconstruction.A method for reconstructing the charge of incident high energy cosmic-ray particles is introduced. The detection efficiency of each PSD strip is verified to be above 99.5%; the total efficiency of the PSD for charged particles is above 99.99%.展开更多
Traditional plastic scintillator has respectively low gamma energy resolution.Space radiation detection need the plastic scintillator to keep a relatively better energy resolution for gamma.Thus we did experiments to ...Traditional plastic scintillator has respectively low gamma energy resolution.Space radiation detection need the plastic scintillator to keep a relatively better energy resolution for gamma.Thus we did experiments to study how to get it enhanced by adding light guider and chamfer.A 9000 Bq radioactive source 60 Co has been utilized to make the experiment and results came that when keeping other conditions same,the height of poly methyl methacrylate(PMMA)light guider changes from 12 mm to 40 mm and the energy resolutions varied from 72.3%to63.5% respectively.Furthermore,another contrast experiment was made to decide whether plastic scintillator with light guiders or integrated chamfer can get better energy resolution.In conclusion the plastic scintillator with integrated chamfer got 55.0%.Through the study of adding light guider or chamfer to plastic scintillator,the gamma energy resolution has been improved greatly from 72.3%to 55.0%.展开更多
In this study,an online detector system based on plastic scintillators is designed to monitor the activity of tritiated water in the liquid effluents of nuclear power plants.The feasibility of the detector is verified...In this study,an online detector system based on plastic scintillators is designed to monitor the activity of tritiated water in the liquid effluents of nuclear power plants.The feasibility of the detector is verified via simulation on Geant4,and the optimal detector structure size is determined.A back-end electronics system is designed and an experimental measurement platform forβ-rays based on a ^(40)KCl solution is constructed.Thirteen ^(40)KC solutions with different activities ranging from 10 to4500 Bq/L are measured,and 1300 V is determined as the optimal operating high voltage of the photomultiplier tubes.A linear fit is performed in 10-min counts,and the maximum linear goodness of fit(R^(2))achieved is 0.9992.Long-term stability measurements are performed for two detectors,one filled with air and the other with a ^(40)KCl solution exhibiting an activity of 2000 Bq/L.The relative deviation of the counts of the detector system every 10 min is 0.998%when the ^(40)KCl solution is used,and the maximum Gaussian R^(2) of the counts is 0.9849.展开更多
The evolution of lead halide perovskites used for X-ray imaging scintillators has been facilitated by the development of solution-processable semiconductors characterized by large-area,flexible,fast photoresponse.The ...The evolution of lead halide perovskites used for X-ray imaging scintillators has been facilitated by the development of solution-processable semiconductors characterized by large-area,flexible,fast photoresponse.The stability and durability of these new perovskites are insufficient to achieve extended computed tomography scanning times with hard X-rays.In this study,we fabricated a self-assembled CsPbBr_(3)-based scintillator film with a flexible large-area uniform thickness using a new roomtemperature solution-processable method.The sensitivity and responsivity of X-ray photon conversion were quantitatively measured and showed a good linear response relationship suitable for X-ray imaging.We also demonstrated,for the first time,that the self-assembled CsPbBr_(3)-based scintillator has good stability for hard X-ray microtomography.Therefore,such an inexpensive solution-processed semiconductor easily prepared at room temperature can be used as a hard X-ray scintillator and equipped with flexible CsPbBr3-based X-ray detectors.It has great potential in three-dimensional high-resolution phase-contrast X-ray-imaging applications in biomedicine and material science because of its heavy Pb and Br atoms.展开更多
In recent years, the increasing demand of various fields of radiation detection materials has led to intensive researches in scintillation materials 1-2]. The scintillators can absorb high-energy X-ray photons and the...In recent years, the increasing demand of various fields of radiation detection materials has led to intensive researches in scintillation materials 1-2]. The scintillators can absorb high-energy X-ray photons and then convert them into low-energy visible photons, which are widely applied in radiation monitoring, security detection, X-ray astronomy and medical radiology 3"l].展开更多
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...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.展开更多
Non-vanishing electromagnetic properties of neutrinos have been predicted by many theories beyond the Standard Model, and an enhanced neutrino magnetic moment can have profound implications for fundamental physics. Th...Non-vanishing electromagnetic properties of neutrinos have been predicted by many theories beyond the Standard Model, and an enhanced neutrino magnetic moment can have profound implications for fundamental physics. The XENON1T experiment recently detected an excess of electron recoil events in the 1–7 keV energy range, which can be compatible with solar neutrino magnetic moment interaction at a most probable value of μ_(v) = 2.1 × 10^(-11)μ_(B).However, tritium backgrounds or solar axion interaction in this energy window are equally plausible causes.Upcoming multi-tonne noble liquid detectors will test these scenarios more in depth, but will continue to face similar ambiguity. We report a unique capability of future large liquid scintillator detectors to help resolve the potential neutrino magnetic moment scenario. With O(100) kton·year exposure of liquid scintillator to solar neutrinos, a sensitivity of μ_(v) < 10^(-11)μ_(B) can be reached at an energy threshold greater than 40 keV, where no tritium or solar axion events but only neutrino magnetic moment signal is still present.展开更多
A new satellite – that will help humanity to unravel the mysteries of the “Dark Matter” – was launched on Thursday Dec. 7. 2015 by China. The launch of the DAMPE satellite took place at 00:12 UTC at the Jiuquan Sa...A new satellite – that will help humanity to unravel the mysteries of the “Dark Matter” – was launched on Thursday Dec. 7. 2015 by China. The launch of the DAMPE satellite took place at 00:12 UTC at the Jiuquan Satellite Launch Center. The new satellite will run in a sun-synchronous orbit with an altitude of 500 km and an inclination of 97.4? with 3 a lifetime.展开更多
A new ΔE-E telescope has been constructed at the external target hall of CSRm[? ]. It is composed of 7 layers ofCsI(Tl) crystals. For each crystal, 4 photomultiplier tubes (PMTs) is coupled to the truncated corners f...A new ΔE-E telescope has been constructed at the external target hall of CSRm[? ]. It is composed of 7 layers ofCsI(Tl) crystals. For each crystal, 4 photomultiplier tubes (PMTs) is coupled to the truncated corners for collectingscintillation light. Each crystal has an active area of 50 mm 50 mm, and the thickness of the crystals are between5 and 10 mm. According to the requests of different experiments, the combination and the ordering of the layerscould be different. In order to achieve good uniformity of light collection, the dressing of each crystal was carefullychosen. The first three layers of the crystals are coated with ESR film, and the others are packed with 7 m Al-Foil.展开更多
基金the National Natural Science Foundation of China(Nos.11875282,11475205 and 12022505)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA10011200)the Youth Innovation Promotion Association of CAS.
文摘This study presents the design and performance results for compact plastic scintillator strips using a wavelength shifting fiber(WLS-fiber)readout with dimensions of 0.1 m×0.02 m×2 m.This approach was evaluated as a candidate for a cosmic-ray muon detector for the Taishan Antineutrino Observatory(JUNO-TAO).The strips coupled with 3-inch photomultiplier tubes(PMTs)were measured and compared between the single-end and double-end readout options.Additionally,a strip using the double-end option coupling with a silicon photomultiplier(SiPM)was further evaluated and compared with the results obtained using PMTs.The performance of the strips was determined by a detailed survey along their length with a cosmicray muon after detailed characterization of the 3-inch PMTs and SiPMs.The proposed design employing a compact plastic scintillator strip with WLS-fiber coupling to a SiPM provides a good choice for cosmic-ray muon veto detectors,particularly when detector dimensions must be limited.
基金supported by the School of Physics at Sun Yat-sen University,China
文摘Plastic scintillators(PSs)embedded with wavelength-shifting fibers are widely used in high-energy particle physics,such as in muon taggers,as well as in medical physics and other applications.In this study,a simulation package was built to evaluate the effects of the diameter and layout of optical fibers on the light yield with different configurations.The optimal optical configuration was designed based on simulations and validated using two PS prototypes under certain experimental condi-tions.A top veto tracker(TVT)for the JUNO-TAO experiment,comprising four layers of 160 strips of PS,was designed and evaluated.The threshold was evaluated when the muon tagging efficiency of a PS strip was>99%.The efficiency of three layer out of four layer of TVT is>99%,even with a tagging efficiency of a single strip as low as 97%,using a threshold of 10 photoelectrons and assuming a 40%silicon PM photon detection efficiency.
基金supported by the Key Laboratory of Nuclear Data Foundation(No.JCKY2022201C153)National Natural Science Foundation of China(No.11505216),Educational Commission of Hunan Province of China(No.19B488)Natural Science Foundation of Hunan Province of China(Nos.2021JJ40444 and 2020RC3054).
文摘To reduce the experimental uncertainty in the 235 U resonance energy region and improve the detection efficiency for neutron total cross section measurements compared with those obtained with the neutron total cross section spectrometer(NTOX), a dedicated lithium-containing scintillation detector has been developed on the Back-n beam line at the China Spallation Neutron Source. The Fast Scintillator-based Neutron Total Cross Section(FAST) spectrometer has been designed based on a Cs2Li La Br6(CLLB) scintillator considering the γ-ray flash and neutron environment on the Back-n beam line. The response of the CLLB scintillator to neutrons and γ-rays was evaluated with different 6Li/7 Li abundance ratios using Geant4. The neutron-γdiscrimination performance of the CLLB has been simulated considering different scintillation parameters, physical designs,and light readout modes. A cubic 6Li-enriched( > 90%) CLLB scintillator, which has a thickness of 4-9 mm and side length of no less than 50 mm to cover the Φ 50 mm neutron beam at the spectrometer position, has been proposed coupling to a side readout SiPM array to construct the FAST spectrometer. The developed simulation techniques for neutron-γ discrimination performance could provide technical support for other neutron-induced reaction measurements on the Back-n beam line.
基金supported by the National Key R&D Program of China(No.2018YFA0404100)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.12175257)+1 种基金the National Natural Science Foundation of China(No.12175257)the Science Foundation of High-Level Talents of Wuyi University(No.2021AL027).
文摘High-precision vertex and energy reconstruction are crucial for large liquid scintillator detectors such as that at the Jiangmen Underground Neutrino Observatory(JUNO),especially for the determination of neutrino mass ordering by analyzing the energy spectrum of reactor neutrinos.This paper presents a data-driven method to obtain a more realistic and accurate expected PMT response of positron events in JUNO and develops a simultaneous vertex and energy reconstruction method that combines the charge and time information of PMTs.For the JUNO detector,the impact of the vertex inaccuracy on the energy resolution is approximately 0.6%.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11975255 and 11875273)Guangdong Basic and Applied Basic Research Foundation (Grant No. 2020B1515120025)。
文摘Chinese Spallation Neutron Source(CSNS) has successfully produced its first neutron beam in 28th August 2017. It has been running steadily from March, 2018. According to the construction plan, the engineering materials diffractometer(EMD) will be installed between 2019–2023. This instrument requires the neutron detectors with the cover area near3 m2in two 90° neutron diffraction angle positions, the neutron detecting efficiency is better than 40%@1A, and the spatial resolution is better than 4 mm×200 mm in horizontal and vertical directions respectively. We have developed a onedimensional position-sensitive neutron detector based on the oblique6Li F/Zn S(Ag) scintillators, wavelength shifting fibers,and Si PMs(silicon photomultipliers) readout. The inhomogeneity of the neutron detection efficiency between each pixel and each detector module, which caused by the inconsistency of the wave-length shifting fibers in collecting scintillation photons, needs to be mitigated before the installation. A performance optimization experiment of the detector modules was carried out on the BL20(beam line 20) of CSNS. Using water sample, the neutron beam with Φ5 mm exit hole was dispersed related evenly into the forward space. According to the neutron counts of each pixel of the detector module, the readout electronics threshold of each pixel is adjusted. Compared with the unadjusted detector module, the inhomogeneity of the detection efficiency for the adjusted one has been improved from 69% to 90%. The test result of the diffraction peak of the standard sample Si showed that the adjusted detector module works well.
基金Project supported by the National Natural Science Foundation of China (50572115) and Basic Research Key Project of Shanghai Municipal (09JC1406500)
文摘The synthesis of cerium-doped lutetium oxyorthosilicate (LSO) polycrystalline powders was investigated by a hydrothermal proc-ess. The precursor was obtained by the hydrothermal reaction of Lu(NO3)3 with Na2SiO3 at 200 ℃ for 10 h by using urea as precipitator, fol-lowed by a calcination uader proper temperatures. The results of XRD indicated that the precursor was crystallized into A-type LSO phase at 1000 ℃, and transfetrred to B-type LSO phase when temperature was raised above 1050 ℃. After being heated at 1250 ℃ for 2 h, single phase of B-type LSO powder was synthesized with homogeneous distribution of particle size ranging from 200 to 300 nm. The photolumi-nescence spectrum of as-synthesized LSO: Ce powders showed a typical broad emission peak centered at 404 nm, corresponding to the 5d1-4f transition of Ce3+.
基金supported by the National Natural Science Foundation of China(Nos.11805294 and 11975021)the China Postdoctoral Science Foundation(2018M631013),the Strategic Priority Research Program of Chinese Academy of Sciences(XDA10010900)+1 种基金the Fundamental Research Funds for the Central Universities,Sun Yatsen University(19lgpy268)in part by the CAS Center for Excellence in Particle Physics(CCEPP).
文摘Large-volume liquid scintillator detectors with ultra-low background levels have been widely used to study neutrino physics and search for dark matter.Event vertex and event time are not only useful for event selection but also essential for the reconstruction of event energy.In this study,four event vertex and event time reconstruction algorithms using charge and time information collected by photomultiplier tubes were analyzed comprehensively.The effects of photomultiplier tube properties were also investigated.The results indicate that the transit time spread is the main effect degrading the vertex reconstruction,while the effect of dark noise is limited.In addition,when the event is close to the detector boundary,the charge information provides better performance for vertex reconstruction than the time information.
基金the Natural Science Foundation of China (NSFC 10535050)
文摘Daya Bay reactor anti-neutrino experiment is designed to measure an important parameter, θ13, of neutrino by using anti-neutrino created by Daya Bay and Ling Ao nuclear power plants. The experiment need 200 tonnes gadolinium loaded liquid scintillator (Gd-LS) as target. The purpose of this research is to develop suitable Gd-LS candidates for this experiment, which should have long attenuation length, high light yield, long term stability, and should be compatible with the material used to build the containers. Two kinds of Gd-LS were developed using carboxylic acids 2-ethylhexanoic acid (EHA) and 3, 5, 5-trimethylhexanoic acid (TMHA) as complexing ligands and mesitylene and linear alkyl benzene (LAB) as scintillator solvents. Four Gd-LS samples with different Gd content and complexing ligands were prepared and characterized. The relative light yields and the stabilities of all samples are satisfying, and the values of attenuation length show that TMHA is a better ligand than EHA.
文摘Ce （3+） doped Y3Al5O12 （Ce （3+）∶YAG） single crystal is an good scintillator due to its excellent thermal,mechanic and scintillant performances. In this paper,its vacuum ultraviolet and fluorescence spectra using the synchrotron radiation as the excitation source was studied. The ultraviolet-visible excitation and absorption spectra of Ce （3+）∶YAG were also measured. The excitation energy transfer process and the luminescent differences under direct excitation into the 5d bands of Ce （3+） and excitation of valence band in Ce （3+）∶YAG scintillator were studied.
基金supported by the National Natural Science Foundation of China(Nos.11975021,12175257,12175321,11675275,and U1932101)the Guangdong Basic and Applied Basic Research Foundation(No.2021A1515012039)+3 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA10010900)the National College Students Science and Technology Innovation Projectthe Undergraduate Base Scientific Research Project of Sun Yat-sen Universitythe CAS Center for Excellence in Particle Physics(CCEPP).
文摘The precise vertex reconstruction for large liquid scintillator detectors is essential.A novel machine learning-based method was successfully developed to reconstruct an event vertex in JUNO.In this study,the performance of machine learning-based vertex reconstruction was further improved by optimizing the input images of neural networks.By separating the information of different types of PMTs and adding the information of the second hit of PMTs,the vertex resolution was improved by approximately 9.4% at 1 MeV and 9.8% at 11 MeV.
基金supported by the National Natural Science Foundation of China (Nos.11675232 and 12175286)。
文摘Fast beam range measurements are required to maximize the time available for patient treatment, given that the beam range requires verification with respect to quality assurance to maintain accelerator commissioning standards and ensure patient safety. A novel beam range monitor based on a plastic scintillator and multi-pixel photon counter (MPPC) arrays is therefore proposed in this paper. The monitor was constructed using 128 plastic scintillator films with a thickness of 1 mm and an active area of 50 × 50 mm^(2). A customized MPPC array read the scintillation light of each film. The advantage of dividing the active detector volume into films is that it intercepts the particle beam and enables direct differential light yield measurement in each film, in addition to depth-light curve generation without the need for image analysis A GEANT4 simulation, including scintillator quenching effects, was implemented, and the results revealed that Birks’ law exhibited a slight little influence on the position of the beam range, only changing the shape and absolute normalization of the Bragg curve, which is appropriate for the calculation of the beam range using the depth-light curve. The performance of the monitor was evaluated using a heavy-ion medical machine in Wuwei City, Gansu Province, China. The beam range measurement accuracy of the monitor was 1 mm, and the maximum difference between the measured and reference ranges was less than0.2%, thus indicating that the monitor can meet clinica carbon ion therapy requirements.
基金funded by the National Key Research and Development Program of China (2016YFA0400201)supported by the National Natural Science Foundation of China (11673047,11673075, 11303107, U1738127 and U1738205)
文摘The DArk Matter Particle Explorer(DAMPE) is a space-borne apparatus for detecting the highenergy cosmic-ray-like electrons, γ-rays, protons and heavy ions. The Plastic Scintillator Detector(PSD)is the top-most sub-detector of the DAMPE. The PSD is designed to measure the charge of incident highenergy particles and it also serves as a veto detector for discriminating γ-rays from charged particles. In this paper, a PSD on-orbit calibration procedure is described, which includes the five steps of pedestal, dynode correlation, response to minimum-ionizing particles, light attenuation function and energy reconstruction.A method for reconstructing the charge of incident high energy cosmic-ray particles is introduced. The detection efficiency of each PSD strip is verified to be above 99.5%; the total efficiency of the PSD for charged particles is above 99.99%.
基金supported by the National Natural Science Foundation of China including Research on the Technology of Fast Neutron Location Sensitive Detector Based on GEM and Data Acquisition(No.11575073)the Space Neutron Telescope Detection Technology(No.11775114)
文摘Traditional plastic scintillator has respectively low gamma energy resolution.Space radiation detection need the plastic scintillator to keep a relatively better energy resolution for gamma.Thus we did experiments to study how to get it enhanced by adding light guider and chamfer.A 9000 Bq radioactive source 60 Co has been utilized to make the experiment and results came that when keeping other conditions same,the height of poly methyl methacrylate(PMMA)light guider changes from 12 mm to 40 mm and the energy resolutions varied from 72.3%to63.5% respectively.Furthermore,another contrast experiment was made to decide whether plastic scintillator with light guiders or integrated chamfer can get better energy resolution.In conclusion the plastic scintillator with integrated chamfer got 55.0%.Through the study of adding light guider or chamfer to plastic scintillator,the gamma energy resolution has been improved greatly from 72.3%to 55.0%.
基金supported by the National Natural Science Foundation of China (No. 12105029)。
文摘In this study,an online detector system based on plastic scintillators is designed to monitor the activity of tritiated water in the liquid effluents of nuclear power plants.The feasibility of the detector is verified via simulation on Geant4,and the optimal detector structure size is determined.A back-end electronics system is designed and an experimental measurement platform forβ-rays based on a ^(40)KCl solution is constructed.Thirteen ^(40)KC solutions with different activities ranging from 10 to4500 Bq/L are measured,and 1300 V is determined as the optimal operating high voltage of the photomultiplier tubes.A linear fit is performed in 10-min counts,and the maximum linear goodness of fit(R^(2))achieved is 0.9992.Long-term stability measurements are performed for two detectors,one filled with air and the other with a ^(40)KCl solution exhibiting an activity of 2000 Bq/L.The relative deviation of the counts of the detector system every 10 min is 0.998%when the ^(40)KCl solution is used,and the maximum Gaussian R^(2) of the counts is 0.9849.
基金supported by National Natural Science Foundation of China (No. 12175127)Natural Science Foundation of Shandong Province,China (No. ZR2020MA088)
文摘The evolution of lead halide perovskites used for X-ray imaging scintillators has been facilitated by the development of solution-processable semiconductors characterized by large-area,flexible,fast photoresponse.The stability and durability of these new perovskites are insufficient to achieve extended computed tomography scanning times with hard X-rays.In this study,we fabricated a self-assembled CsPbBr_(3)-based scintillator film with a flexible large-area uniform thickness using a new roomtemperature solution-processable method.The sensitivity and responsivity of X-ray photon conversion were quantitatively measured and showed a good linear response relationship suitable for X-ray imaging.We also demonstrated,for the first time,that the self-assembled CsPbBr_(3)-based scintillator has good stability for hard X-ray microtomography.Therefore,such an inexpensive solution-processed semiconductor easily prepared at room temperature can be used as a hard X-ray scintillator and equipped with flexible CsPbBr3-based X-ray detectors.It has great potential in three-dimensional high-resolution phase-contrast X-ray-imaging applications in biomedicine and material science because of its heavy Pb and Br atoms.
文摘In recent years, the increasing demand of various fields of radiation detection materials has led to intensive researches in scintillation materials 1-2]. The scintillators can absorb high-energy X-ray photons and then convert them into low-energy visible photons, which are widely applied in radiation monitoring, security detection, X-ray astronomy and medical radiology 3"l].
文摘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.
基金Supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA10010800)the Double First Class Start-up Fund (WF220442603) provided by Shanghai Jiao Tong Universitysupport from the CAS Center for Excellence in Particle Physics (CCEPP)。
文摘Non-vanishing electromagnetic properties of neutrinos have been predicted by many theories beyond the Standard Model, and an enhanced neutrino magnetic moment can have profound implications for fundamental physics. The XENON1T experiment recently detected an excess of electron recoil events in the 1–7 keV energy range, which can be compatible with solar neutrino magnetic moment interaction at a most probable value of μ_(v) = 2.1 × 10^(-11)μ_(B).However, tritium backgrounds or solar axion interaction in this energy window are equally plausible causes.Upcoming multi-tonne noble liquid detectors will test these scenarios more in depth, but will continue to face similar ambiguity. We report a unique capability of future large liquid scintillator detectors to help resolve the potential neutrino magnetic moment scenario. With O(100) kton·year exposure of liquid scintillator to solar neutrinos, a sensitivity of μ_(v) < 10^(-11)μ_(B) can be reached at an energy threshold greater than 40 keV, where no tritium or solar axion events but only neutrino magnetic moment signal is still present.
文摘A new satellite – that will help humanity to unravel the mysteries of the “Dark Matter” – was launched on Thursday Dec. 7. 2015 by China. The launch of the DAMPE satellite took place at 00:12 UTC at the Jiuquan Satellite Launch Center. The new satellite will run in a sun-synchronous orbit with an altitude of 500 km and an inclination of 97.4? with 3 a lifetime.
文摘A new ΔE-E telescope has been constructed at the external target hall of CSRm[? ]. It is composed of 7 layers ofCsI(Tl) crystals. For each crystal, 4 photomultiplier tubes (PMTs) is coupled to the truncated corners for collectingscintillation light. Each crystal has an active area of 50 mm 50 mm, and the thickness of the crystals are between5 and 10 mm. According to the requests of different experiments, the combination and the ordering of the layerscould be different. In order to achieve good uniformity of light collection, the dressing of each crystal was carefullychosen. The first three layers of the crystals are coated with ESR film, and the others are packed with 7 m Al-Foil.
