Design optimization of plastic scintillators with wavelength-shifting fibers and silicon photomultiplier readouts in the top veto tracker of the JUNO-TAO experiment

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.

Tunable Radioluminescence Perovskite Nanocrystal Scintillators

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].

Design and preliminary test of tritiated water online detector system based on plastic scintillators

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.

Hydrophobic long-chain two-dimensional perovskite scintillators for underwater X-ray imaging

The underwater X-ray imaging technology development is significant to subaqueous target reconnaissance/detection/identification, subfluvial archaeology,submerged resource exploration, etc. As the core of X-ray imaging detection, the scintillator has been plagued by inherent moisture absorption and decomposition, and strict requirements for seamless packaging and waterproofing.Here, we designed a manganese-doped two-dimensional(2D) perovskite scintillator modified by hydrophobic longchain organic amine through the combination of component and doping engineering. The modified perovskites show high water repellency that can be used as an underwater X-ray scintillator. X-ray images of aquatic organisms or other objects with a high spatial resolution of10 lp·mm^(-1) at a big view field(32 mm × 32 mm) were obtained by scintillation screen. This hydrophobic perovskite scintillator based on molecular design is of great promise in underwater X-ray nondestructive testing technology development.

Pressure-induced emission(PIE)in halide perovskites toward promising applications in scintillators and solid-state lighting

High-pressure chemistry has provided a huge boost to the development of scientific community.Pressure-induced emission(PIE)in halide perovskites is gradually showing its unique charm in both pressure sensing and optoelectronic device applications.Moreover,the PIE retention of halide perovskites under ambient conditions is of great commercial value.Herein,we mainly focus on the potential applications of PIE and PIE retention in metal halide perovskites for scintillators and solid-state lighting.Based on the performance requirements of scintillator and single-component white light-emitting diodes(WLEDs),the significance of PIE and PIE retention is critically clarified,aiming to design and synthesize materials used for high-performance optoelectronic devices.This perspective not only demonstrates promising applications of PIE in the fields of scintillators and WLEDs,but also provides potential applications in display imaging and anti-counterfeiting of PIE materials.Furthermore,solving the scientific disputes that exist under ambient conditions is also simply discussed as an outlook by introducing high-pressure dimension to produce PIE.

Tb^(3+)-doped borosilicate glass scintillators for highresolution X-ray imaging

Scintillators are the vital component in X-ray perspective image technology that is applied in medical imaging,industrial nondestructive testing,and safety testing.But the high cost and small size of single-crystal commercialized scintillators limit their practical application.Here,a series of Tb^(3+)-doped borosilicate glass(BSG)scintillators with big production size,low cost,and high spatial resolution are designed and fabricated.The structural,photoluminescent,and scintillant properties are systematically investigated.Benefiting from excellent transmittance(87%at 600 nm),high interquantum efficiency(60.7%),and high X-ray excited luminescence(217%of Bi4Ge3O12),the optimal sample shows superhigh spatial resolution(exceeding 20 lp/mm).This research suggests that Tb^(3+)-doped BSG scintillators have potential applications in the static X-ray imaging field.

Ce^(3+):Lu_(3)Al_(5)O_(12)–Al_(2)O_(3) optical nanoceramic scintillators elaborated via a low-temperature glass crystallization route

Transparent Ce:lutetium aluminum garnet(Ce:Lu_(3)A_(l5)O_(12),Ce:LuAG)ceramics have been regarded as potential scintillator materials due to their relatively high density and atomic number(Zeff).However,the current Ce:LuAG ceramics exhibit a light yield much lower than the expected theoretical value due to the inevitable presence of LuAl antisite defects at high sintering temperatures.This work demonstrates a low-temperature(1100℃)synthetic strategy for elaborating transparent LuAG–Al_(2)O_(3) nanoceramics through the crystallization of 72 mol%Al_(2)O_(3)–28 mol%Lu_(2)O_(3)(ALu28)bulk glass.The biphasic nanostructure composed of LuAG and Al_(2)O_(3) nanocrystals makes up the whole ceramic materials.Most of Al_(2)O_(3) is distributed among LuAG grains,and the rest is present inside the LuAG grains.Fully dense biphasic LuAG–Al_(2)O_(3) nanoceramics are highly transparent from the visible region to mid-infrared(MIR)region,and particularly the transmittance reaches 82%at 780 nm.Moreover,LuAl antisite defect-related centers are completely undetectable in X-ray excited luminescence(XEL)spectra of Ce:LuAG–Al_(2)O_(3) nanoceramics with 0.3–1.0 at%Ce.The light yield of 0.3 at%Ce:LuAG–Al_(2)O_(3) nanoceramics is estimated to be 20,000 ph/MeV with short 1μs shaping time,which is far superior to that of commercial Bi_(4)Ge_(3)O_(12)(BGO)single crystals.These results show that a low-temperature glass crystallization route provides an alternative approach for eliminating the antisite defects in LuAG-based ceramics,and is promising to produce garnet-based ceramic materials with excellent properties,thereby meeting the demands of advanced scintillation applications.

Recent advances,challenges,and opportunities of inorganic nanoscintillators

This review article highlights the exploration of inorganic nanoscintillators for various scientific and technological applications in the fields of radiation detection,bioimaging,and medical theranostics.Various aspects of nanoscintillators pertaining to their fundamental principles,mechanism,structure,applications are briefly discussed.The mechanisms of inorganic nanoscintillators are explained based on the fundamental principles,instrumentation involved,and associated physical and chemical phenomena,etc.Subsequently,the promise of nanoscintillators over the existing single-crystal scintillators and other types of scintillators is presented,enabling their development for multifunctional applications.The processes governing the scintillation mechanisms in nanodomains,such as surface,structure,quantum,and dielectric confinement,are explained to reveal the underlying nanoscale scintillation phenomena.Additionally,suitable examples are provided to explain these processes based on the published data.Furthermore,we attempt to explain the different types of inorganic nanoscintillators in terms of the powder nanoparticles,thin films,nanoceramics,and glasses to ensure that the effect of nanoscience in different nanoscintillator domains can be appreciated.The limitations of nanoscintillators arc also highlighted in this review article.The advantages of nanostructured scintillators,including their property-driven applications,are also explained.This review article presents the considerable application potential of nanostructured scintillators with respect to important aspects as well as their physical and application significance in a concise manner.

Development and prospects of garnet ceramic scintillators:A review

Garnet ceramic scintillators are a class of inorganic scintillation materials with excellent overall performance.The flexibility of cation substitution in different lattice positions leads to tunable and versatile properties and a wide range of applications.This paper starts with an overview of the development history of the inorganic scintillation materials,followed by a description of major preparation methods and characterization of garnet scintillation ceramics.Great progress obtained in recent years consisting in applying the band-gap and defect engineering strategies to the garnet scintillation ceramics is reviewed.Finally,the respective problems in the preparation and performance of multicomponent garnet single crystals and ceramics and the effective solutions are discussed.The garnet scintillation ceramics with the highest application potential are summarized,and the future development directions are proposed.

Optimized online filter stack spectrometer for ultrashort X-ray pulses

Currently,with the advent of high-repetition-rate laser-plasma experiments,the demand for online diagnosis for the X-ray spectrum is increasing because the laser-plasma-generated X-ray spectrum is very important for characterizing electron dynamics and applications.In this study,scintillators and silicon PIN(P-type–intrinsic-N-type semiconductor)diodes were used to construct a wideband online filter stack spectrometer.The X-ray sensor and filter arrangement was optimized using a genetic algorithm to minimize the condition number of the response matrix.Consequently,the unfolding error was significantly reduced based on numerical experiments.The detector responses were quantitatively calibrated by irradiating the scintillator and PIN diode with various nuclides and comparing the measuredγ-ray peaks.A prototype 15-channel spectrometer was developed by integrating an X-ray detector with front-and back-end electronics.The prototype spectrometer could record X-ray pulse signals at a repetition rate of 1 kHz.Furthermore,an optimized spectrometer was employed to record the real-time spectra of laser-driven bremsstrahlung sources.This optimized spectrometer offers a compact solution for spectrum diagnostics of ultrashort X-ray pulses,exhibiting improved accuracy in terms of spectrum measurements and repetition rates,and could be widely used in next-generation high-repetition-rate high-power laser facilities.

Design of hadronic calorimeter for DarkSHINE experiment

The sensitivity of the dark photon search through invisible decay final states in low-background experiments relies sig-nificantly on the neutron and muon veto efficiencies,which depend on the amount of material used and the design of the detector geometry.This paper presents the optimized design of the hadronic calorimeter(HCAL)used in the DarkSHINE experiment,which is studied using a GEANT4-based simulation framework.The geometry is optimized by comparing a traditional design with uniform absorbers to one that uses different thicknesses at different locations on the detector,which enhances the efficiency of vetoing low-energy neutrons at the sub-GeV level.The overall size and total amount of material used in the HCAL are optimized to be lower,owing to the load and budget requirements,whereas the overall performance is studied to satisfy the physical objectives.

Development of a scintillating-fiber-based beam monitor for the coherent muon-to-electron transition experiment

The coherent muon-to-electron transition(COMET)experiment is a leading experiment for the coherent conversion of μ^(-)N→e^(-)N using a high-intensity pulsed muon beamline,produced using innovative slow-extraction techniques.Therefore,it is critical to measure the muon beam characteristics.We set up a muon beam monitor(MBM),where scintillating fibers woven in a cross shape were coupled to silicon photomultipliers to measure the spatial profile and timing structure of the extracted muon beam for the COMET.The MBM detector was tested successfully with a proton beamline at the China Spallation Neutron Source and took data with good performance in the commissioning run.The development of the MBM,including its mechanical structure,electronic readout,and beam measurement results,are discussed.

Development of an enhanced online tritium monitoring system using plastic scintillation fiber array

Tritium,a radioactive nuclide discharged by nuclear power plants,poses challenges for removal.Continuous online monitoring of tritium in water is crucial for real-time radiation data,given its predominant existence in the environment as water.This paper presents the design,simulation,and development of a tritium monitoring device utilizing a plastic scintillation fiber(PSF)array.Experimental validation confirmed the device’s detection efficiency and minimum detectable activity.The recorded detection efficiency of the device is 1.6×10^(-3),which exceeds the theoretically simulated value of 4×10^(-4)by four times.Without shielding,the device can achieve a minimum detectable activity of 3165 Bq L^(-1)over a 1600-second measurement duration.According to simulation and experimental results,enhancing detection efficiency is possible by increasing the number and length of PSFs and implementing rigorous shielding measures.Additionally,reducing the diameter of PSFs can also improve detection efficiency.The minimum detectable activity of the device can be further reduced using the aforementioned methods.

A new calibration method for radon detector in seismic systems

Radon observation is an important measurement item of seismic precursor network observation.The radon detector calibration is a key technical link for ensuring radon observation accuracy.At present,the radon detector calibration in seismic systems in China is faced with a series of bottleneck problems,such as aging and scrap,acquisition difficulties,high supervision costs,and transportation limitations of radon sources.As a result,a large number of radon detectors cannot be accurately calibrated regularly,seriously affecting the accuracy and reliability of radon observation data in China.To solve this problem,a new calibration method for radon detectors was established.The advantage of this method is that the dangerous radioactive substance,i.e.,the radon source,can be avoided,but only“standard instruments”and water samples with certain dissolved radon concentrations can be used to realize radon detector calibration.This method avoids the risk of radioactive leakage and solves the current widespread difficulties and bottleneck of radon detector calibration in seismic systems in China.The comparison experiment with the traditional calibration method shows that the error of the calibration coefficient obtained by the new method is less than 5%compared with that by the traditional method,which meets the requirements of seismic observation systems,confirming the reliability of the new method.This new method can completely replace the traditional calibration method of using a radon source in seismic systems.

FPGA implementation of 500-MHz high-count-rate high-time-resolution real-time digital neutron-gamma discrimination for fast liquid detectors

Fast neutron flux measurements with high count rates and high time resolution have important applications in equipment such as tokamaks.In this study,real-time neutron and gamma discrimination was implemented on a self-developed 500-Msps,12-bit digitizer,and the neutron and gamma spectra were calculated directly on an FPGA.A fast neutron flux measurement system with BC-501A and EJ-309 liquid scintillator detectors was developed and a fast neutron measurement experiment was successfully performed on the HL-2 M tokamak at the Southwestern Institute of Physics,China.The experimental results demonstrated that the system obtained the neutron and gamma spectra with a time accuracy of 1 ms.At count rates of up to 1 Mcps,the figure of merit was greater than 1.05 for energies between 50 keV and 2.8 MeV.

Production and test of sPHENIX W/SciFiber electromagnetic calorimeter blocks in China

The sPHENIX experiment is a new generation of large acceptance detectors at the relativistic heavy ion collider at Brookhaven National Laboratory,with scientific goals focusing on probing the strongly interacting Quark–Gluon plasma with hard probes of jets,open heavy flavor particles,andγproduction.The EMCal detector,which covers the pseudo-rapidity region of|η|≤1.1,is an essential subsystem of sPHENIX.In this study,we focused on producing and testing EMCal blocks covering a pseudo-rapidity of|η|∈[0.8,1.1].These,in conjunction with the central pseudo-rapidity EMCal blocks,significantly enhance the sPHENIX physics capability of the jet andγparticle measurements.In this paper,the detector module production and testing of sPHENIX W-powder/scintillating fiber(W/ScFi)electromagnetic calorimeter blocks are presented.The selection of the tungsten powder,mold fabrication,QA procedures,and cosmic ray test results are discussed.

In-beam gamma rays of CSNS Back-n characterized by black resonance filter

The back-streaming white-neutron beamline(Back-n)of the China Spallation Neutron Source is an essential neutronresearch platform built for the study of nuclear data,neutron physics,and neutron applications.Many types of cross-sectional neutron-reaction measurements have been performed at Back-n since early 2018.These measurements have shown that a significant number of gamma rays can be transmitted to the experimental stations of Back-n along with the neutron beam.These gamma rays,commonly referred to as in-beam gamma rays,can induce a non-negligible experimental background in neutron-reaction measurements.Studying the characteristics of in-beam gamma rays is important for understanding the experimental background.However,measuring in-beam gamma rays is challenging because most gamma-ray detectors are sensitive to neutrons;thus,discriminating between neutron-induced signals and those from in-beam gamma rays is difficult.In this study,we propose the use of the black resonance filter method and a CeBr_(3) scintillation detector to measure the characteristics of the in-beam gamma rays of Back-n.Four types of black resonance filters,^(181)Ta,^(59)Co,^(nat)Ag,and^(nat)Cd,were used in this measurement.The time-of-flight(TOF)technique was used to select the detector signals remaining in the absorption region of the TOF spectra,which were mainly induced by in-beam gamma rays.The energy distribution and flux of the in-beam gamma rays of Back-n were determined by analyzing the deposited energy spectra of the CeBr_(3) scintillation detector and using Monte Carlo simulations.Based on the results of this study,the background contributions from in-beam gamma rays in neutron-reaction measurements at Back-n can be reasonably evaluated,which is beneficial for enhancing both the experimental methodology and data analysis.

Development of novel rare earth doped fluoride and oxide scintillators for two-dimensional imaging

Two topics were focused. The first one was about the gamma-ray scintillator, Pr^3＋：Lu3Al5O12 （LuAG）. The second one was about neutron scintillator, Ce^3＋：^6LiCaAlF6 and Eu^2＋：^6LiCaAlF6 （^6LiCAF）. Those scintillators have been developed very recently for modem imaging applications in the medical and homeland security fields. In both cases, the rare earth ions are playing the crucial role as emission centers. Pr^3＋ in LuAG provided fast 5d→4f transition providing noticeably shorter decay time than that of Ce^3＋. Among several candidate hosts, LuAG showed the best performance. Bulk crystal growth, basic scintillation properties, two-dimensional gamma-ray imaging and positron emission mammography （PEM） application were demonstrated. Due to the international situation, the homeland security was compromized by illicit traffic of explosives, drugs, nuclear materials, etc. and the ways to its improvement became an important R＆D topic. For this purpose the Ce and Eu doped LiCAF appeared competitive candidates. Especially, when substitution of 3He neutron detectors was considered, the discrimination ability of gamma-ray from alpha-ray was important. Bulk crystal growth, basic scintillation properties and two-dimensional neutron imaging were demonstrated.

Temperature dependence of the light yield of the LAB-based and mesitylene-based liquid scintillators

We studied the temperature dependence of the light yield of linear alkyl benzene （LAB）-based and mesitylene-based liquid scintillators. The light yield increases by 23% for both liquid scintillators when the temper- ature is lowered from 26 ℃ to -40 ℃, correcting for the temperature response of the photomultiplier tube. The measurements help to understand the energy response of liquid scintillator detectors. Especially, the next generation reactor neutrino experiments for neutrino mass hierarchy, such as the Jiangmen Underground Neutrino Observatory （JUNO）, require very high energy resolution. As no apparent degradation on the liquid scintillator transparency was observed, lowering the operation temperature of the detector to ～4 ℃ will increase the photoelectron yield of the detector by 13%, combining the light yield increase of the liquid scintillator and the quantum efficiency increase of the photomultiplier tubes.

Studies of detector cells for a hadronic calorimeter based on plastic scintillators

In this paper,we study variations of a plastic scintillator tile coupled to silicon photomultiplier via a dome-shaped cavity originally developed in the CALICE collaboration.Four kinds of plastic scintillator detector cells with different sizes based on the structure were studied for applications in analog readout highly granular hadronic calorimeter(AHCAL)in future circular electron positron collider(CEPC)project.The responses to cosmic rays of the detector cells could reach 33.89 p.e./MIPs(minimum ionizing particles).The good results of both response uniformity and MIP detection efficiency(above 95%)show that the detector cells with larger sizes(40×40×3 and 50×50×3 mm^(3))could provide an option for AHCAL detector cells of CEPC detectors.