The quality of PMT signals is crucial for large-size and high-precision neutrino experiments, but most of these experiments are affected by the overshoot of PMT signals from the positive HV-single cable scheme. Oversh...The quality of PMT signals is crucial for large-size and high-precision neutrino experiments, but most of these experiments are affected by the overshoot of PMT signals from the positive HV-single cable scheme. Overshoot affects the trigger, dead time and charge measurement from a detector. For the JUNO prototype detector, we have performed a detailed study and calculation on PMT signal overshoot to control the ratio of overshoot to signal amplitude to;%, with no effect on other PMT parameters.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
The Jiangmen Underground Neutrino Observatory(JUNO)is a large liquid scintillator detector designed to explore many topics in fundamental physics.In this study,the potential of searching for proton decay in the p→νK...The Jiangmen Underground Neutrino Observatory(JUNO)is a large liquid scintillator detector designed to explore many topics in fundamental physics.In this study,the potential of searching for proton decay in the p→νK^(+)mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification.Moreover,the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals.Based on these advantages,the detection efficiency for the proton decay via p→νK^(+)is 36.9%±4.9%with a background level of 0.2±0.05(syst)±0.2(stat)events after 10 years of data collection.The estimated sensitivity based on 200 kton-years of exposure is 9.6×1033 years,which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies.展开更多
In the past few decades,numerous searches have been made for the neutrinoless double-beta decay（0νββ） process,aiming to establish whether neutrinos are their own antiparticles（Majorana neutrinos）,but no 0νββ...In the past few decades,numerous searches have been made for the neutrinoless double-beta decay（0νββ） process,aiming to establish whether neutrinos are their own antiparticles（Majorana neutrinos）,but no 0νββdecay signal has yet been observed.A number of new experiments are proposed but they ultimately suffer from a common problem： the sensitivity may not increase indefinitely with the target mass.We have performed a detailed analysis of the physics potential by using the Jiangmen Underground Neutrino Observatory（JUNO） to improve the sensitivity to 0νββ up to a few me V,a major step forward with respect to the experiments currently being planned.JUNO is a 20 kton low-background liquid scintillator（LS） detector with 3%/（E（MeV））1/2 energy resolution,now under construction.It is feasible to build a balloon filled with enriched xenon gas（with136Xe up to 80%） dissolved in LS,inserted into the central region of the JUNO LS.The energy resolution is 1.9% at the Q-value of 136Xe 0νββ decay.Ultra-low background is the key for 0νββ decay searches.Detailed studies of background rates from intrinsic 2νββ and 8B solar neutrinos,natural radioactivity,and cosmogenic radionuclides（including light isotopes and 137Xe） were performed and several muon veto schemes were developed.We find that JUNO has the potential to reach a sensitivity（at 90% C.L.） to T1/20νββof 1.8×1028yr（5.6×1027yr） with 50 tons（5 tons） of fiducial136 Xe and 5 years exposure,while in the 50-ton case the corresponding sensitivity to the effective neutrino mass,mββ,could reach（5–12） meV,covering completely the allowed region of inverted neutrino mass ordering.展开更多
Liquid scintillator （LS） will be adopted as the detector material in JUNO （Jiangmen Underground Neutrino Observatory）. The energy resolution requirement of JUNO is 3%, which has never previously been reached. To a...Liquid scintillator （LS） will be adopted as the detector material in JUNO （Jiangmen Underground Neutrino Observatory）. The energy resolution requirement of JUNO is 3%, which has never previously been reached. To achieve this energy resolution, the light yield of liquid scintillator is an important factor. PPO （the fluor） and bis-MSB （the wavelength shifter） are the two main materials dissolved in LAB. To study the influence of these two materials on the transmission of scintillation photons in LS, 25 and 12 cm-long quartz vessels were used in a light yield experiment. LS samples with different concentration of PPO and bis-MSB were tested. At these lengths, the light yield growth is not obvious when the concentration of PPO is higher than 4 g/L. The influence from bis-MSB becomes insignificant when its concentration is higher than 8 mg/L. This result could provide some useful suggestions for the JUNO LS.展开更多
In this study,we present the large photomultiplier tube(PMT)afterpulse measurement results obtained from the Jiangmen underground neutrino observatory(JUNO)experiment.A total of 11 dynode-PMTs(R12860)from the Hamamats...In this study,we present the large photomultiplier tube(PMT)afterpulse measurement results obtained from the Jiangmen underground neutrino observatory(JUNO)experiment.A total of 11 dynode-PMTs(R12860)from the Hamamatsu company(Hamamatsu Photonics K.K.(HPK))and 150 micro-channel plate PMTs(MCP-PMTs,GDB-6201)from the NNVT company(North Night Vision Technology Co.,Ltd.(NNVT))were tested.Subsequently,an afterpulse model was built according to the afterpulse time distribution and the probability of occurrence for these two types of PMTs.The average ratio of the total afterpulse charge with a delay between 0.5μs and 20μs to the primary pulse charge is∼5.7%(13.2%)for the tested MCPPMTs(dynode-PMTs).The JUNO experiment will deploy 20,01220-inch PMTs;this study will benefit detector simulation,event reconstruction,and data analysis regarding the JUNO experiment.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
Background The Jiangmen underground neutrino observatory(JUNO)is a new generation of long-term operation neutrino experimental platform under construction in Jiangmen,Guangdong province of southern China.The underwate...Background The Jiangmen underground neutrino observatory(JUNO)is a new generation of long-term operation neutrino experimental platform under construction in Jiangmen,Guangdong province of southern China.The underwater frontend and readout electronics(F&R electronics)are placed nearby the 20-inch PMTs and readout current signals from three PMTs.The electronics are sealed in a stainless-steel underwater box to keep them dry,and temperature control of the electronics plays a significant role in their reliability.Methods A conductive cooling structure based on the passive cooling method is designed for the 20-inch PMT F&R electronics.Both numerical simulation and experimental tests were performed to evaluate the cooling structures'thermal performance.Results The results show that the case temperature of the respective chip for 20-inch PMT F&R electronics is less than 30℃in ambient still water.Conclusion The case temperature of the respective chip meets the strict temperature requirement for the F&R electronics.The JUNO collaboration has adopted this cooling structure for the 20-inch PMT readout electronics.展开更多
A total of 25,6003-inch PMTs will be installed in Jiangmen Underground Neutrino Observatory(JUNO)to achieve more precise energy calibration and to extend the physics detection potential.Performances of all bare PMTs h...A total of 25,6003-inch PMTs will be installed in Jiangmen Underground Neutrino Observatory(JUNO)to achieve more precise energy calibration and to extend the physics detection potential.Performances of all bare PMTs have been characterized and these PMTs are being instrumented with the high voltage divider,underwater front-end cable,and connector.In this paper,we present a dedicated study on signal quality at different stages of the instrumentation.An optimized high voltage ratio was confirmed andfinalized which improved the PMT transit time spread by 25%.The signal charge was attenuated by 22.5%(13.0%)in the 10 m(5 m)cable and it required the addition of 45 V(23 V)to compensate for the loss of PMT gain.There was a 1%overshoot following the PMT signal and no sign of reflection in the connector.A group of 163-inch PMTs with the full instrumentation was installed in the JUNO prototype detector together with a few 8-inch and 20-inch PMTs,which showed good stability and demonstrated a photon detection system with multiple types of PMTs.展开更多
A thorough detector response calibration using radioactive sources is necessary for the Jiangmen Underground Neutrino Observatory. Herein, we discuss the design of a source positioning system based on ultrasonic techn...A thorough detector response calibration using radioactive sources is necessary for the Jiangmen Underground Neutrino Observatory. Herein, we discuss the design of a source positioning system based on ultrasonic technology, aiming for a 3-cm precision over the entire35-m diameter detector sphere. A prototype system is constructed and demonstrated for the experiment.展开更多
The Jiangmen Underground Neutrino Observatory（JUNO） detector is designed to determine the neutrino mass hierarchy and precisely measure oscillation parameters. The general purpose design also allows measurements of ...The Jiangmen Underground Neutrino Observatory（JUNO） detector is designed to determine the neutrino mass hierarchy and precisely measure oscillation parameters. The general purpose design also allows measurements of neutrinos from many terrestrial and non-terrestrial sources. The JUNO Event Data Model（EDM） plays a central role in the offline software system. It describes the event data entities through all processing stages for both simulated and collected data, and provides persistency via the input/output system. Also, the EDM is designed to enable flexible event handling such as event navigation, as well as the splitting of MC IBD signals and mixing of MC backgrounds. This paper describes the design, implementation and performance of the JUNO EDM.展开更多
The flux of geoneutrinos at any point on the Earth is a function of the abundance and distribution of radioactive elements within our planet. This flux has been successfully detected by the 1-kt Kam LAND and 0.3-kt Bo...The flux of geoneutrinos at any point on the Earth is a function of the abundance and distribution of radioactive elements within our planet. This flux has been successfully detected by the 1-kt Kam LAND and 0.3-kt Borexino detectors, with these measurements being limited by their low statistics. The planned 20-kt JUNO detector will provide an exciting opportunity to obtain a high statistics measurement, which will provide data to address several questions of geological importance. This paper presents the JUNO detector design concept, the expected geo-neutrino signal and corresponding backgrounds. The precision level of geo-neutrino measurements at JUNO is obtained with the standard least-squares method. The potential of the Th/U ratio and mantle measurements is also discussed.展开更多
The Jiangmen Underground Neutrino Observatory （JUNO） is a multi-purpose neutrino experiment designed to measure the neutrino mass hierarchy using a central detector （CD）, which contains 20 kton liquid scintillator...The Jiangmen Underground Neutrino Observatory （JUNO） is a multi-purpose neutrino experiment designed to measure the neutrino mass hierarchy using a central detector （CD）, which contains 20 kton liquid scintillator （LS） surrounded by about 17000 photomultiplier tubes （PMTs）. Due to the large fiducial volume and huge number of PMTs, the simulation of a muon particle passing through the CD with the Geant4 toolkit becomes an extremely computation-intensive task. This paper presents a fast simulation implementation using a so-called voxel method： for scintillation photons generated in a certain LS voxel, the PMT＇s response is produced beforehand with Geant4 and then introduced into the simulation at runtime. This parameterisation method successfully speeds up the most CPU consuming process, the optical photon＇s propagation in the LS, by a factor of 50. In the paper, the comparison of physics performance between fast and full simulation is also given.展开更多
基金Supported by Strategic Priority Research Program A-JUNO,High Energy Physics Experiment and Detector R&DNational Natural Science Foundation of China
文摘The quality of PMT signals is crucial for large-size and high-precision neutrino experiments, but most of these experiments are affected by the overshoot of PMT signals from the positive HV-single cable scheme. Overshoot affects the trigger, dead time and charge measurement from a detector. For the JUNO prototype detector, we have performed a detailed study and calculation on PMT signal overshoot to control the ratio of overshoot to signal amplitude to;%, with no effect on other PMT parameters.
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supported by the Chinese Academy of Sciencesthe National Key R&D Program of China+22 种基金the CAS Center for Excellence in Particle PhysicsWuyi Universitythe Tsung-Dao Lee Institute of Shanghai Jiao Tong University in Chinathe Institut National de Physique Nucléaire et de Physique de Particules (IN2P3) in Francethe Istituto Nazionale di Fisica Nucleare (INFN) in Italythe Italian-Chinese collaborative research program MAECI-NSFCthe Fond de la Recherche Scientifique (F.R.S-FNRS)FWO under the "Excellence of Science-EOS" in Belgiumthe Conselho Nacional de Desenvolvimento Científico e Tecnològico in Brazilthe Agencia Nacional de Investigacion y Desarrollo in Chilethe Charles University Research Centrethe Ministry of Education,Youth,and Sports in Czech Republicthe Deutsche Forschungsgemeinschaft (DFG)the Helmholtz Associationthe Cluster of Excellence PRISMA+ in Germanythe Joint Institute of Nuclear Research (JINR)Lomonosov Moscow State University in Russiathe joint Russian Science Foundation (RSF)National Natural Science Foundation of China (NSFC) research programthe MOST and MOE in Taiwan,Chinathe Chulalongkorn UniversitySuranaree University of Technology in Thailandthe University of California at Irvine in USA
文摘The Jiangmen Underground Neutrino Observatory(JUNO)is a large liquid scintillator detector designed to explore many topics in fundamental physics.In this study,the potential of searching for proton decay in the p→νK^(+)mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification.Moreover,the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals.Based on these advantages,the detection efficiency for the proton decay via p→νK^(+)is 36.9%±4.9%with a background level of 0.2±0.05(syst)±0.2(stat)events after 10 years of data collection.The estimated sensitivity based on 200 kton-years of exposure is 9.6×1033 years,which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies.
基金Supported by Strategic Priority Research Program of Chinese Academy of Sciences(XDA10010900)CAS Center for Excellence in Particle Physics(CCEPP)+1 种基金Postdoctoral Science Foundation of China and Chinese Academy of Sciences(2015IHEPBSH101)Program of International S&T Cooperation of Mo ST(2015DFG02000)
文摘In the past few decades,numerous searches have been made for the neutrinoless double-beta decay（0νββ） process,aiming to establish whether neutrinos are their own antiparticles（Majorana neutrinos）,but no 0νββdecay signal has yet been observed.A number of new experiments are proposed but they ultimately suffer from a common problem： the sensitivity may not increase indefinitely with the target mass.We have performed a detailed analysis of the physics potential by using the Jiangmen Underground Neutrino Observatory（JUNO） to improve the sensitivity to 0νββ up to a few me V,a major step forward with respect to the experiments currently being planned.JUNO is a 20 kton low-background liquid scintillator（LS） detector with 3%/（E（MeV））1/2 energy resolution,now under construction.It is feasible to build a balloon filled with enriched xenon gas（with136Xe up to 80%） dissolved in LS,inserted into the central region of the JUNO LS.The energy resolution is 1.9% at the Q-value of 136Xe 0νββ decay.Ultra-low background is the key for 0νββ decay searches.Detailed studies of background rates from intrinsic 2νββ and 8B solar neutrinos,natural radioactivity,and cosmogenic radionuclides（including light isotopes and 137Xe） were performed and several muon veto schemes were developed.We find that JUNO has the potential to reach a sensitivity（at 90% C.L.） to T1/20νββof 1.8×1028yr（5.6×1027yr） with 50 tons（5 tons） of fiducial136 Xe and 5 years exposure,while in the 50-ton case the corresponding sensitivity to the effective neutrino mass,mββ,could reach（5–12） meV,covering completely the allowed region of inverted neutrino mass ordering.
基金Supported by Strategic Priority Research Program of Chinese Academy of Sciences(XDA10010500)National Natural Science Foundation of China(11390384)CAS Center for Excellence in Particle Physics(CCEPP)
文摘Liquid scintillator （LS） will be adopted as the detector material in JUNO （Jiangmen Underground Neutrino Observatory）. The energy resolution requirement of JUNO is 3%, which has never previously been reached. To achieve this energy resolution, the light yield of liquid scintillator is an important factor. PPO （the fluor） and bis-MSB （the wavelength shifter） are the two main materials dissolved in LAB. To study the influence of these two materials on the transmission of scintillation photons in LS, 25 and 12 cm-long quartz vessels were used in a light yield experiment. LS samples with different concentration of PPO and bis-MSB were tested. At these lengths, the light yield growth is not obvious when the concentration of PPO is higher than 4 g/L. The influence from bis-MSB becomes insignificant when its concentration is higher than 8 mg/L. This result could provide some useful suggestions for the JUNO LS.
基金supported by Strategic Priority Research Program of the Chinese Academy of Sciences (No. XDA10011100),Joint Institute of Nuclear Research (JINR),Russia and Lomonosov Moscow State University in Russia,joint Russian Science Foundation (RSF),DFG (Deutsche Forschungsgemeinschaft)National Natural Science Foundation of China (Nos. 12090062 and 12075087)
文摘In this study,we present the large photomultiplier tube(PMT)afterpulse measurement results obtained from the Jiangmen underground neutrino observatory(JUNO)experiment.A total of 11 dynode-PMTs(R12860)from the Hamamatsu company(Hamamatsu Photonics K.K.(HPK))and 150 micro-channel plate PMTs(MCP-PMTs,GDB-6201)from the NNVT company(North Night Vision Technology Co.,Ltd.(NNVT))were tested.Subsequently,an afterpulse model was built according to the afterpulse time distribution and the probability of occurrence for these two types of PMTs.The average ratio of the total afterpulse charge with a delay between 0.5μs and 20μs to the primary pulse charge is∼5.7%(13.2%)for the tested MCPPMTs(dynode-PMTs).The JUNO experiment will deploy 20,01220-inch PMTs;this study will benefit detector simulation,event reconstruction,and data analysis regarding the JUNO experiment.
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This work was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA100102).
文摘Background The Jiangmen underground neutrino observatory(JUNO)is a new generation of long-term operation neutrino experimental platform under construction in Jiangmen,Guangdong province of southern China.The underwater frontend and readout electronics(F&R electronics)are placed nearby the 20-inch PMTs and readout current signals from three PMTs.The electronics are sealed in a stainless-steel underwater box to keep them dry,and temperature control of the electronics plays a significant role in their reliability.Methods A conductive cooling structure based on the passive cooling method is designed for the 20-inch PMT F&R electronics.Both numerical simulation and experimental tests were performed to evaluate the cooling structures'thermal performance.Results The results show that the case temperature of the respective chip for 20-inch PMT F&R electronics is less than 30℃in ambient still water.Conclusion The case temperature of the respective chip meets the strict temperature requirement for the F&R electronics.The JUNO collaboration has adopted this cooling structure for the 20-inch PMT readout electronics.
文摘A total of 25,6003-inch PMTs will be installed in Jiangmen Underground Neutrino Observatory(JUNO)to achieve more precise energy calibration and to extend the physics detection potential.Performances of all bare PMTs have been characterized and these PMTs are being instrumented with the high voltage divider,underwater front-end cable,and connector.In this paper,we present a dedicated study on signal quality at different stages of the instrumentation.An optimized high voltage ratio was confirmed andfinalized which improved the PMT transit time spread by 25%.The signal charge was attenuated by 22.5%(13.0%)in the 10 m(5 m)cable and it required the addition of 45 V(23 V)to compensate for the loss of PMT gain.There was a 1%overshoot following the PMT signal and no sign of reflection in the connector.A group of 163-inch PMTs with the full instrumentation was installed in the JUNO prototype detector together with a few 8-inch and 20-inch PMTs,which showed good stability and demonstrated a photon detection system with multiple types of PMTs.
基金supported by the ‘‘Strategic Priority Research Program’’ of the Chinese Academy of Sciences(No.XDA10010800)the ‘‘Fundamental Research Funds for the Central Universities’’(No.3102017zy010)
文摘A thorough detector response calibration using radioactive sources is necessary for the Jiangmen Underground Neutrino Observatory. Herein, we discuss the design of a source positioning system based on ultrasonic technology, aiming for a 3-cm precision over the entire35-m diameter detector sphere. A prototype system is constructed and demonstrated for the experiment.
基金Supported by Joint Large-Scale Scientific Facility Funds of the NSFC and CAS(U1532258)the Program for New Century Excellent Talents in University(NCET-13-0342)+1 种基金the Shandong Natural Science Funds for Distinguished Young Scholar(JQ201402)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA10010900)
文摘The Jiangmen Underground Neutrino Observatory（JUNO） detector is designed to determine the neutrino mass hierarchy and precisely measure oscillation parameters. The general purpose design also allows measurements of neutrinos from many terrestrial and non-terrestrial sources. The JUNO Event Data Model（EDM） plays a central role in the offline software system. It describes the event data entities through all processing stages for both simulated and collected data, and provides persistency via the input/output system. Also, the EDM is designed to enable flexible event handling such as event navigation, as well as the splitting of MC IBD signals and mixing of MC backgrounds. This paper describes the design, implementation and performance of the JUNO EDM.
基金Supported in part by National Natural Science Foundation of China(11405056,11305193,11205176,21504063)National Science Foundation of U.S.(EAR 1067983/1068097)+1 种基金Strategic Priority Research Program of the Chinese Academy of Sciences under Grant No.XDA10010100 CAS Center for Excellence in Particle Physics(CCEPP)
文摘The flux of geoneutrinos at any point on the Earth is a function of the abundance and distribution of radioactive elements within our planet. This flux has been successfully detected by the 1-kt Kam LAND and 0.3-kt Borexino detectors, with these measurements being limited by their low statistics. The planned 20-kt JUNO detector will provide an exciting opportunity to obtain a high statistics measurement, which will provide data to address several questions of geological importance. This paper presents the JUNO detector design concept, the expected geo-neutrino signal and corresponding backgrounds. The precision level of geo-neutrino measurements at JUNO is obtained with the standard least-squares method. The potential of the Th/U ratio and mantle measurements is also discussed.
基金Supported by Strategic Priority Research Program of Chinese Academy of Sciences(XDA10010900)National Natural Science Foundation of China(11405279,11575224)
文摘The Jiangmen Underground Neutrino Observatory （JUNO） is a multi-purpose neutrino experiment designed to measure the neutrino mass hierarchy using a central detector （CD）, which contains 20 kton liquid scintillator （LS） surrounded by about 17000 photomultiplier tubes （PMTs）. Due to the large fiducial volume and huge number of PMTs, the simulation of a muon particle passing through the CD with the Geant4 toolkit becomes an extremely computation-intensive task. This paper presents a fast simulation implementation using a so-called voxel method： for scintillation photons generated in a certain LS voxel, the PMT＇s response is produced beforehand with Geant4 and then introduced into the simulation at runtime. This parameterisation method successfully speeds up the most CPU consuming process, the optical photon＇s propagation in the LS, by a factor of 50. In the paper, the comparison of physics performance between fast and full simulation is also given.
