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
nd Photon detection efficiency is a key parameter of PMTs in high-precision neutrino and dark matter experiments,while normally the quantum efficiency is used with a normalization factor and angular response as the de...nd Photon detection efficiency is a key parameter of PMTs in high-precision neutrino and dark matter experiments,while normally the quantum efficiency is used with a normalization factor and angular response as the detection efficiency,where it is always coupled with detector response from the calibration normalization.Here,the absolute photon detection efficiency of 20′′PMTs in photon-counting level is further considered rather than the combination of quantum efficiency and normalization factors.Purpose and method In order to have a good understanding of photon detection efficiency of the large-area PMT,we conduct a detailed comparison of relative collection efficiencies of a series of PMTs with spotlight.This study is based on the tests of relative quantum efficiency and relative detection efficiency,checked with several light intensities.Conclusion All the results are consistent in relative QE and DE measurement with different light intensities,and the error of each parameter is coupled in our studies.Based on the measurements,Hamamatsu R12860 shows the maximum collection efficiency with spotlight at PMT center,and Hamamatsu R12199,R1355 and HZC XP72B22 have the same level of CE within the uncertainty.Discussion Following the configuration on incident light and DE definition,we can further define the DE of a large-area PMT with similar algorithms,which will also be used for detector simulation in JUNO.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
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
为确定500 m口径球面射电望远镜(Five-hundred-meter Aperture Spherical radio Telescope,FAST)与其周边公众移动通信(Public Mobile Telecommunications,PMT)系统的电磁兼容(electromagnetic compatibility,EMC)特性,本文综合论述了F...为确定500 m口径球面射电望远镜(Five-hundred-meter Aperture Spherical radio Telescope,FAST)与其周边公众移动通信(Public Mobile Telecommunications,PMT)系统的电磁兼容(electromagnetic compatibility,EMC)特性,本文综合论述了FAST宁静区内中国移动、中国联通和中国电信三大运营商所属PMT基站对其产生的电磁干扰。首先,从射电天文业务的频谱划分谈起,论述了射电天文业务干扰源类型,引出了其运行保护标准,进而针对FAST详细说明了FAST宁静区的用频法规和保护要求;其次,分析了ITU-R建议电波传播预测与干扰分析方法,并通过实地测量验证了该方法的适用性,进一步针对性地分析了PMT基站的电磁辐射传播特性,综合评估了FAST宁静区内PMT基站的干扰情况:FAST宁静区域90.24%的PMT基站在一定程度上均会对FAST产生干扰,而在所选分析条件下,仅有43.14%的数据符合FAST保护要求;最后,针对PMT基站干扰信号的抑制和消除,分析了常用的射电天文射频干扰抑制方法,同时为保障FAST免受PMT基站干扰,从FAST和PMT基站的角度出发论述了可行的用频防护措施,并基于实施难度、经济成本、策略收益和通信质量4类指标建立了防护方法的评估体系,对所提防护方法进行了实例说明。上述研究成果可为保障FAST的安全观测提供技术基础。展开更多
利用惩罚最大T检验(Penalized Maximal T test,PMT)方法,选取均一的邻近气象站为参考站,基于月平均地面气温(SAT)资料,利用相关系数权重平均方法构建参考序列,同时结合元数据信息,对1960-2011年中国沿海27个海洋观测站月平均海表温度(S...利用惩罚最大T检验(Penalized Maximal T test,PMT)方法,选取均一的邻近气象站为参考站,基于月平均地面气温(SAT)资料,利用相关系数权重平均方法构建参考序列,同时结合元数据信息,对1960-2011年中国沿海27个海洋观测站月平均海表温度(SST)进行了均一性检验与订正,并分析了造成海表温度序列非均一的主要原因。结果表明,中国沿海海洋台站海表温度资料存在较为严重的非均一性问题,几乎所有的台站都存在断点,仪器变更(包括人工观测转自动观测)(占总断点数的52.4%)和迁站(占总断点数的33.3%)是造成序列非均一的主要原因。整套资料负订正量所占比例较高,这种负订正量与人工转自动观测后海表温度观测值偏低有密切关系。这也使得订正后中国沿海平均海表温度趋势与订正前存在明显差异,订正后中国沿海海表温度呈明显的加速上升趋势。展开更多
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.
文摘nd Photon detection efficiency is a key parameter of PMTs in high-precision neutrino and dark matter experiments,while normally the quantum efficiency is used with a normalization factor and angular response as the detection efficiency,where it is always coupled with detector response from the calibration normalization.Here,the absolute photon detection efficiency of 20′′PMTs in photon-counting level is further considered rather than the combination of quantum efficiency and normalization factors.Purpose and method In order to have a good understanding of photon detection efficiency of the large-area PMT,we conduct a detailed comparison of relative collection efficiencies of a series of PMTs with spotlight.This study is based on the tests of relative quantum efficiency and relative detection efficiency,checked with several light intensities.Conclusion All the results are consistent in relative QE and DE measurement with different light intensities,and the error of each parameter is coupled in our studies.Based on the measurements,Hamamatsu R12860 shows the maximum collection efficiency with spotlight at PMT center,and Hamamatsu R12199,R1355 and HZC XP72B22 have the same level of CE within the uncertainty.Discussion Following the configuration on incident light and DE definition,we can further define the DE of a large-area PMT with similar algorithms,which will also be used for detector simulation in JUNO.
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.
文摘为确定500 m口径球面射电望远镜(Five-hundred-meter Aperture Spherical radio Telescope,FAST)与其周边公众移动通信(Public Mobile Telecommunications,PMT)系统的电磁兼容(electromagnetic compatibility,EMC)特性,本文综合论述了FAST宁静区内中国移动、中国联通和中国电信三大运营商所属PMT基站对其产生的电磁干扰。首先,从射电天文业务的频谱划分谈起,论述了射电天文业务干扰源类型,引出了其运行保护标准,进而针对FAST详细说明了FAST宁静区的用频法规和保护要求;其次,分析了ITU-R建议电波传播预测与干扰分析方法,并通过实地测量验证了该方法的适用性,进一步针对性地分析了PMT基站的电磁辐射传播特性,综合评估了FAST宁静区内PMT基站的干扰情况:FAST宁静区域90.24%的PMT基站在一定程度上均会对FAST产生干扰,而在所选分析条件下,仅有43.14%的数据符合FAST保护要求;最后,针对PMT基站干扰信号的抑制和消除,分析了常用的射电天文射频干扰抑制方法,同时为保障FAST免受PMT基站干扰,从FAST和PMT基站的角度出发论述了可行的用频防护措施,并基于实施难度、经济成本、策略收益和通信质量4类指标建立了防护方法的评估体系,对所提防护方法进行了实例说明。上述研究成果可为保障FAST的安全观测提供技术基础。
文摘利用惩罚最大T检验(Penalized Maximal T test,PMT)方法,选取均一的邻近气象站为参考站,基于月平均地面气温(SAT)资料,利用相关系数权重平均方法构建参考序列,同时结合元数据信息,对1960-2011年中国沿海27个海洋观测站月平均海表温度(SST)进行了均一性检验与订正,并分析了造成海表温度序列非均一的主要原因。结果表明,中国沿海海洋台站海表温度资料存在较为严重的非均一性问题,几乎所有的台站都存在断点,仪器变更(包括人工观测转自动观测)(占总断点数的52.4%)和迁站(占总断点数的33.3%)是造成序列非均一的主要原因。整套资料负订正量所占比例较高,这种负订正量与人工转自动观测后海表温度观测值偏低有密切关系。这也使得订正后中国沿海平均海表温度趋势与订正前存在明显差异,订正后中国沿海海表温度呈明显的加速上升趋势。
