Performance of compact plastic scintillator strips with wavelength shifting fibers using a photomultiplier tube or silicon photomultiplier readout

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.

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.

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.

Design and development of a plastic scintillator based whole body β/γ contamination monitoring system

Plastic scintillation detectors based whole body β/γ contamination monitors are developed for use in radiation facilities.This microcontroller-based multi-detector system uses 13 plastic scintillator detectors,with minimized dead detection zones,monitoring the whole body,and conforming to the contamination limit prescribed by the regulatory authority.This system has the features for monitoring hands,feet,head,and faceβ/γusing contamination monitors and portal exit monitors.It can detect gamma sources at a dose rate of 10 n Gyh^(-1).The system is calibrated using b sources^(90)Sr/^(90)Y,^(204)Tl,and^(36)Cl,and the efficiency is found to be 29%,22%,and 18%,respectively.Theminimumdetectableβ/γcontaminationis0.15 Bqcm^(-2),which is significantly less than the minimum detection objectives on head,face,hands,and feet.

Plastic scintillator detector for qualitative and quantitative measurements of gamma radiation

Background Plastic scintillator detectors are rugged and easily manufactured in desired shape,sizes and response time to gamma radiation is prompt as compared with any other scintillator detectors.Being popular these detectors are used in radiation monitors one of the application to restrict radioactive material movement.These are used in gross counting mode to know the presence of radioactivity.Therefore secondary survey is required to know the nature of the radionuclides.Purpose The feasibility study of Cylindrical Plastic Scintillator Detector(CPSD)was carried out for the qualitative and quantitative assessment of gamma emitting radionuclides.Methods In this work limited gamma spectrometry was carried out using NE110 equivalent cylindrical plastic scintillating material of 5.1 cm diameter and 100 cm long.CPSD is optically coupled to photomultiplier tube(PMT).The detector signal is processed using preamplifier,shaping amplifier and further analysed by a multi channel analyser(MCA).CPSD gamma spectrum consists of Compton continuum and Gaussian shaped Compton edge energy(λ_(e))appearing as Compton maxima energy(λ_(max)).Photon transport simulation is used to characterizeλ_(max) as a signature for radionuclides emitting gamma energy/energies.In case of unresolved gamma energies,it appears as weighted effective Compton maxima energy.The prominent gamma energies observed across nuclear industries are in the energy range 0.03–3 MeV.It is grouped as low energy,intermediate energy,high energy and ultra-high energy window.The simulated spectrum is obtained suing Gaussian broadening parameters deduced from experimentally measured spectrum.The efficiency response function is developed from simulated response of detector to standard gamma sources under known source detector configurations.Results The mono energetic gamma emitting radioisotopes are identified againstλ_(max) from data library.Qualitative analysis of spectrum is used to discriminate artificial radioactive material from naturally occurring radioactive material using gamma photon,corresponding Compton edge and expected Compton maxima in each energy window.The provisional quantitative assessment is carried out using efficiency deduced from response function.The detection efficiency varies within 1%–0.2%for 0.03 to 3 MeV gamma energies.In this study efficiency for ^(137)Cs source is 0.26%with FWHM 0.092 MeV and the results re within 15%for the measured activity.Estimated sensitivity and spectral dose rate coefficient for CPSD are 77 cps/µR/h and 44.29 nGy/kcps respectively.The MDA or MDL of the most prominent radioisotopes used in nuclear industry are estimated.CPSD showed an ability to detect 149 kBq,^(137)Cs radioisotope at 1 m distance.Conclusion CPSD can be utilised for gamma isotope identification with limited gamma spectroscopy tool in contamination and dose rate measurements monitors.

Measurements of the light output functions of plastic scintillator using ~9Be(d,n)^(10)B reaction neutron source

The light output functions for protons of ST-401 and BC-408 plastic scintillators were measured using white neutron source produced by the 9Be（d,n） 10B reaction at the HI-13 Tandem Accelerator at China Institute of Atomic Energy（CIAE）.The LOFs of plastic scintillators for protons in the energy range of 0.5-16.5 MeV were obtained by the time-of-flight（TOF） technique and an iterative procedure.Two parameters（kB and C） were deduced by fitting the experimental data.

Testing and analysis of the plastic scintillator units for LHAASO-ED

Background A total of 5195 electromagnetic particle detectors(EDs)are used in the 1-square-kilometer extensive air shower array(KM2A),which is a subarray of the Large High Altitude Air Shower Observatory(LHAASO).Purpose As the detection sensitive medium of the EDs,more than 20,000 plastic scintillator units(BC-408),produced by Saint-Gobain,are used in LHAASO.It is important to monitor the light output of the scintillator units among the units.Method To improve the efficiency,a sampling inspection scheme(misjudgment rate of less than 5%)was designed,and a batch test system was developed.Ten units of scintillator units can be measured at a time.The test system selects the single muon events of cosmic rays to measure the light output values of the plastic scintillator units.Results The measurement has an uncertainty of less than 2%.By pretest calibration,the difference between different channels can be eliminated.The calibration was implemented approximately every 3 months,and the test system had been running stably for 28 months.By measuring the ratio of the signals of selected far and near probe events,the changes in the quality of different batches of plastic scintillator units can be demonstrated.Conclusions The test system realized accurate measurement of the light output,and all batches satisfied the requirements of the experiment.

A preliminary simulation study of influence of backsplash on the plastic scintillator detector design in HERD experiment

Background The plastic scintillator detector(PSD)is one of the detectors in the high energy cosmic radiation detection(HERD)facility,which is designed for gamma-ray detection and a redundant charge measurement.Backsplash will lead to a decrease in PSD’s performance of gamma-ray detection and charge measurement,which should be carefully considered.Purpose Two preliminary segmentation schemes of the PSD and two veto strategies have been proposed to suppress the backsplash effect.In this paper,we focus on the influence of the backsplash caused by gamma rays.The gamma-ray trigger efficiency and identification efficiency were studied in the case of different cell sizes and veto strategies,which can provide guidance on the PSD design.Methods A Monte Carlo simulation based on Geant4 has been performed.To simplify the simulation,the PSD is segmented into 1 cm3 cubes which can be easily aggregated into cells with different sizes during analysis.Results and conclusion Side_Veto can be used as a baseline design of veto strategy,whereas Smart_Veto can be selected as an upgraded design.Both the PSD bar cell with a width of less than 11 cm and the PSD tile cell with a width of less than 20 cm can achieve a sufficiently high gamma-ray trigger efficiency(>80%),which realizes the primary goal of the PSD.Meanwhile,both the PSD bar cell with a width of less than 3 cm and the PSD tile cell with a width of less than 20 cm can ensure a sufficiently high gamma-ray identification efficiency(>80%)for photons up to 800 GeV.

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.

Performance of a plastic scintillation fiber dosimeter based on different photoelectric devices

The photoelectric device of a scintillation dosimeter converts photons produced by radiation into an electrical signal.Its features directly determine the overall performance of the dosimeter.For a plastic scintillation fiber dosimeter(PSFD)with a current readout mode,systematic studies of the stability and light-dose response were performed for the photomultiplier tube(PMT),silicon photomultiplier(SiPM),avalanche photodiode(APD),and photodiode(PD).The temperature stability,long-term stability,repeatability,signal-to-noise ratio(SNR),and current dose response of the PSFD with the abovementioned photoelectric devices were studied using a pulsed LED light source and the Small Animal Radiation Therapy platform.An exponential relationship between the dark/ne current and temperature was obtained for all the devices.I is shown that the APD is the most sensitive device to temperature,with a current dependence on temperature reaching 6.5%C^(-1)at room temperature,whereas for the other devices this dependence is always<0:6%C^(-1).In terms of long-term stability,the net current of PD can change by up to 4%when working continuously for 8 h and 2%when working intermittently for 32 h,whereas for the other devices,the changes are all<1%.For the dose response,the PMT and SiPM exhibit excellent linear responses and SNRs within the range of 0.1-60 Gy/min For the PSFD with a current readout mode,the performance of the PMT and SiPM is concluded to be better than that of the other devices in the study.In particular,the SiPM,which has a compact size,low bias voltage,and antimagnetic interference,has great advantages for further applications.

Monte-Carlo simulation to determine detector efficiency of plastic scintillating fiber

Fundamental characteristics of the plastic scintillating fiber (PSF) as a detector for electromagnetic radiation (X & γ) are obtained by GEANT4 detector simulation tool package. The detector response to radiation with energy of 10~400 keV is found out. Energy deposition as well as detector efficiency (DE) of the PSF are studied. In order to make linear array of the PSF for imaging purpose, the optimum length of fiber is also estimated.

Simulation results of the online tritiated water measurement system

Currently,the liquid scintillation method is widely used to measure the activity of tritiated water in the primary circuit of nuclear power plants,which leads to the continuous production of radioactive waste during measurement.In addition,the real-time activity information of tritiated water cannot be obtained.To solve this problem,herein we present an online tritiated water measurement method based on plastic scintillators that used the optical transport process in the Geant 4 software toolkit to build a model of plastic scintillation detection for tritiated water.Through simulation,the basic geometric dimensions of the detector were determined.In this dimension,using one detector to measure for 3 h,when the tritiated water activity was 100 Bq/L,its resolution was 16%(16 Bq/L).In addition,calculations were performed for the presence of other background signals to obtain the minimum detectable concentration.

A simulation study for a cost-effective PET-like detector system intended to track particles in granular assemblies

Since many industrial applications rely on the processing of densely packed and moving granular ma-terial,obtaining bulk internal information on the particle movement inside the reactors is of great importance.Such information can be delivered by Positron Emission Particle Tracking(PEPT).By marking pellets with a positron-emitting radioisotope,the position of these tracer particles can be determined via the time-of-flight differences of the emitted gamma-ray pairs.The current paper proposes a PET-like detector system based on cost-effective organic plastic scintillators instead of the more common but expensive inorganic scintillators.This system is currently under construction and was tested for its resolution and efficiency in this simulation study.Using Monte Carlo simulations and the software toolkit Geant4,three different geometries(an empty glass box,a generic grate system,and a cubic box of 1 m3 completely filled with pellets)were investigated,leading to a spatial resolution in the millimeter range and an efficiency,defined as the ratio of reconstructed decay locations to simulated decays,of 2.7%,1.4%,and 0.3%.

A simulation study on spatial and time resolution for a cost-effective positron emission particle tracking system

This work is the second part of a simulation study investigating the processing of densely packed and moving granular assemblies by positron emission particle tracking (PEPT).Since medical positron emission tomography (PET) scanners commonly used for PEPT are very expensive,a PET-like detector system based on cost-effective organic plastic scintillator bars is being developed and tested for its capabilities.In this context,the spatial resolution of a resting positron source,a source moving on a freely designed model path,and a particle motion given by a discrete element method (DEM) simulation is studied using Monte Carlo simulations and the software toolkit Geant4.This not only extended the simulation and reconstruction to a moving source but also significantly improved the spatial resolution compared to previous work by adding oversampling and iteration to the reconstruction algorithm.Furthermore,in the case of a source following a trajectory developed from DEM simulations,a very good resolution of about 1 mm in all three directions and an average 3D deviation between simulated and reconstructed events of 2.3 mm could be determined.Thus,the resolution for realistic particle motion within the generic grate system (which is the test rig for further experimental studies) is well below the smallest particle size.The simulation of the dependence of the reconstruction accuracy on tracer particle location revealed a nearly constant efficiency within the entire detector system,which demonstrates that boundary effects can be neglected.

Plastic scintillation detectors for precision Time-of-Flight measurements of relativistic heavy ions

Plastic scintillation detectors for Time-of-Flight（TOF） measurements are almost essential for event-byevent identification of relativistic rare isotopes. In this work, a pair of plastic scintillation detectors of dimensions50×50×3^t mm^3and 80×100×3^t mm^3have been set up at the External Target Facility（ETF）, Institute of Modern Physics（IMP）. Their time, energy and position responses are measured with the^（18）O primary beam at 400 Me V/nucleon. After off-line corrections for walk effect and position, the time resolutions of the two detectors are determined to be 27 ps（σ） and 36 ps（σ）, respectively. Both detectors have nearly the same energy resolution of3.1%（σ） and position resolution of about 3.4 mm（σ）. The detectors have been used successfully in nuclear reaction cross section measurements, and will be be employed for upgrading the RIBLL2 beam line at IMP as well as for the high energy branch at HIAF.

A scintillator detector for beam tuning of low-energy single electron accelerator

Purpose Nine scintillator detectors were developed for beam tuning of low-energy single electron accelerator instead of the picoammeter and Faraday cup,both of which will be insensitive to the weak-current beam lower than picoampere.Methods The detectors are based on plastic scintillator and photomultiplier tube(PMT)and the beam is 100 Hz pulsed electrons in the energy range of 0.1 to 50MeV.The beam flux was tuned from about 107 to quasi-single electron for each bunch according to the measurement results of these detectors installed along the beam pipe and after slits.In order to determine the number of electrons in a bunch,the gains of each PMT were finely calibrated,and the energy response of each detector was calibrated with 207Bi radioactive source.Moreover,the deposited energy in the plastic scintillator,the electron detection efficiency and light collection efficiency,as a function of electron incident energy,were also simulated in detail by Geant4.Results Nine detectors worked well at a gain of 0.6×10^(6) after installation in the beam pipe,and the number of electrons in a bunch could be measured at each detector position.The single electron peak was seen when the beam reached the final detector.Conclusion The commissioning result shows that the beam was tuned to quasi-single electron level successfully and the scintillator detector is an effective method to measure the weak-current beam lower than picoampere.

A plastic scintillating fiber position detector in vacuum for the test beam facility at BEPCⅡ-LINAC

Two plastic scintillating fiber position detectors for charged particles have been designed,built and installed inside the vacuum tube near two sides of the DM2 deflection magnet on the E3 beam line of the test beam facility at the BEPC-LINAC.A one-dimensional position resolution of～1 mm with a sensitive area of 60 mm×60 mm has been obtained for this detector.

A high-position-resolution trajectory detector system for cosmic ray muon tomography:Monte Carlo simulation

Purpose The research focuses on the related designing and simulating the high-position-resolution trajectory detector system based on cosmic ray muon tomography.Methods The energy deposition of muon in the detector varies with the length of the ionization path.Results The simulation of the submillimeter detector system was designed for muon imaging.The optimal position resolution of the detector reached 0.6 mm.Conclusions The entire research process includes the selection of analysis of parameters affecting system design,designing of two high-position-resolution detectors based on plastic scintillators,implementation of different imaging algorithms and image quality assessment based on different imaging models.It provides a solution based on high positional resolution plastic scintillator detectors for cosmic ray muon scattering imaging.

Cosmic ray test for a T0 detector

The endcap of time-of-flight （ETOF） detector in BES （Beijing Spectrometer） III is planned to be upgraded by using multi-gap resistive plate chambers （MRPCs） and the designed time resolution of the MRPCs is around 50 ps. Thus a time-zero （TO） detector needs to be built to offer a high quality reference time for the MRPCs beam test. So a TO detector is built using plastic scintillator tiles （BC420） to couple with four fast phototubes （PMTs, Hamamatsu H6533）. The timing properties of the detector is studied by using a cosmic ray test and factors related to the time resolution, such as plastic scintillator size, readout mode and angle effects, are discussed. TO detector timing resolutions of -41-62 ps are achieved, which means that the TO detector can be used in the MRPC beam test.

Physical design of positronium time of f light spectroscopy apparatus

Positronium time of flight spectroscopy（Ps-TOF）is an effective technique for porous material research.It has advantages over other techniques for analyzing the porosity and pore tortuosity of materials.This paper describes a design for Ps-TOF apparatus based on the Beijing intense slow positron beam,supplying a new material characterization technique.In order to improve the time resolution and increase the count rate of the apparatus,the detector system is optimized.For 3 eV o-Ps,the time broadening is 7.66 ns and the count rate is 3 cps after correction.