China Jinping Underground Laboratory(CJPL)is ideal for studying solar,geo-,and supernova neutrinos.A precise measurement of the cosmic-ray background is essential in proceeding with R&D research for these MeV-scal...China Jinping Underground Laboratory(CJPL)is ideal for studying solar,geo-,and supernova neutrinos.A precise measurement of the cosmic-ray background is essential in proceeding with R&D research for these MeV-scale neutrino experiments.Using a 1-ton prototype detector for the Jinping Neutrino Experiment(JNE),we detected 264 high-energy muon events from a 645.2-day dataset from the first phase of CJPL(CJPL-I),reconstructed their directions,and measured the cosmic-ray muon flux to be (3.53±0.22_stat.±0.07_sys.)×-10^(-10)cm^(-2).The observed angular distributions indicate the leakage of cosmic-ray muon background and agree with simulation data accounting for Jinping mountain's terrain.A survey of muon fluxes at different laboratory locations,considering both those situated under mountains and those down mine shafts,indicates that the flux at the former is generally a factor of (4±2) larger than at the latter,with the same vertical overburden.This study provides a convenient back-of-the-envelope estimation for the muon flux of an underground experiment.展开更多
Solar,terrestrial,and supernova neutrino experiments are subject to muon-induced radioactive background.The China Jinping Underground Laboratory(CJPL),with its unique advantage of a 2400 m rock coverage and long dista...Solar,terrestrial,and supernova neutrino experiments are subject to muon-induced radioactive background.The China Jinping Underground Laboratory(CJPL),with its unique advantage of a 2400 m rock coverage and long distance from nuclear power plants,is ideal for MeV-scale neutrino experiments.Using a 1-ton prototype detector of the Jinping Neutrino Experiment(JNE),we detected 3 43 high-energy cosmic-ray muons and(7.86±3.97)muon-induced neutrons from an 820.28-day dataset at the first phase of CJPL(CJPL-I).Based on the muon-induced neutrons,we measured the corresponding muon-induced neutron yield in a liquid scintillator to be(3.44±1.86_(stat.)±0.76_(syst.))×10^(-4) μ^(-1)g^(-1)cm^(2) at an average muon energy of 340 GeV.We provided the first study for such neutron background at CJPL.A global fit including this measurement shows a power-law coefficient of(0.75±0.02) for the dependence of the neutron yield at the liquid scintillator on muon energy.展开更多
The China Jinping Underground Laboratory（CJPL）, which has the lowest cosmic-ray muon flux and the lowest reactor neutrino flux of any laboratory, is ideal to carry out low-energy neutrino experiments. With two detec...The China Jinping Underground Laboratory（CJPL）, which has the lowest cosmic-ray muon flux and the lowest reactor neutrino flux of any laboratory, is ideal to carry out low-energy neutrino experiments. With two detectors and a total fiducial mass of 2000 tons for solar neutrino physics（equivalently, 3000 tons for geo-neutrino and supernova neutrino physics）, the Jinping neutrino experiment will have the potential to identify the neutrinos from the CNO fusion cycles of the Sun, to cover the transition phase for the solar neutrino oscillation from vacuum to matter mixing, and to measure the geo-neutrino flux, including the Th/U ratio. These goals can be fulfilled with mature existing techniques. Efforts on increasing the target mass with multi-modular neutrino detectors and on developing the slow liquid scintillator will increase the Jinping discovery potential in the study of solar neutrinos,geo-neutrinos, supernova neutrinos, and dark matter.展开更多
基金Supported in part by the National Natural Science Foundation of China(11620101004,11475093)the Key Laboratory of Particle&Radiation Imaging(Tsinghua University,the CAS Center for Excellence in Particle Physics(CCEPP),and Guangdong Basic and Applied Basic Research Foundation(2019A1515012216)Portion of this work performed at Brookhaven National Laboratory is supponted in part by the United States Department of Energy(DE-SC0012704)。
文摘China Jinping Underground Laboratory(CJPL)is ideal for studying solar,geo-,and supernova neutrinos.A precise measurement of the cosmic-ray background is essential in proceeding with R&D research for these MeV-scale neutrino experiments.Using a 1-ton prototype detector for the Jinping Neutrino Experiment(JNE),we detected 264 high-energy muon events from a 645.2-day dataset from the first phase of CJPL(CJPL-I),reconstructed their directions,and measured the cosmic-ray muon flux to be (3.53±0.22_stat.±0.07_sys.)×-10^(-10)cm^(-2).The observed angular distributions indicate the leakage of cosmic-ray muon background and agree with simulation data accounting for Jinping mountain's terrain.A survey of muon fluxes at different laboratory locations,considering both those situated under mountains and those down mine shafts,indicates that the flux at the former is generally a factor of (4±2) larger than at the latter,with the same vertical overburden.This study provides a convenient back-of-the-envelope estimation for the muon flux of an underground experiment.
基金Supported in part by the National Natural Science Foundation of China (11620101004,11475093,12127808)the Key Laboratory of Particle&Radiation Imaging(Tsinghua University)+2 种基金the CAS Center for Excellence in Particle Physics (CCEPP)Guangdong Basic and Applied Basic Research Foundation(2019A1515012216)Portion of this work performed at Brookhaven National Laboratory is supported in part by the United States Department of Energy (DESC0012704)。
文摘Solar,terrestrial,and supernova neutrino experiments are subject to muon-induced radioactive background.The China Jinping Underground Laboratory(CJPL),with its unique advantage of a 2400 m rock coverage and long distance from nuclear power plants,is ideal for MeV-scale neutrino experiments.Using a 1-ton prototype detector of the Jinping Neutrino Experiment(JNE),we detected 3 43 high-energy cosmic-ray muons and(7.86±3.97)muon-induced neutrons from an 820.28-day dataset at the first phase of CJPL(CJPL-I).Based on the muon-induced neutrons,we measured the corresponding muon-induced neutron yield in a liquid scintillator to be(3.44±1.86_(stat.)±0.76_(syst.))×10^(-4) μ^(-1)g^(-1)cm^(2) at an average muon energy of 340 GeV.We provided the first study for such neutron background at CJPL.A global fit including this measurement shows a power-law coefficient of(0.75±0.02) for the dependence of the neutron yield at the liquid scintillator on muon energy.
基金Supported by the National Natural Science Foundation of China(11235006,11475093,11135009,11375065,11505301,and11620101004)the Tsinghua University Initiative Scientific Research Program(20121088035,20131089288,and 20151080432)+3 种基金the Key Laboratory of Particle&Radiation Imaging(Tsinghua University)the CAS Center for Excellence in Particle Physics(CCEPP)U.S.National Science Foundation Grant PHY-1404311(Beacom)U.S.Department of Energy under contract DE-AC02-98CH10886(Yeh)
文摘The China Jinping Underground Laboratory（CJPL）, which has the lowest cosmic-ray muon flux and the lowest reactor neutrino flux of any laboratory, is ideal to carry out low-energy neutrino experiments. With two detectors and a total fiducial mass of 2000 tons for solar neutrino physics（equivalently, 3000 tons for geo-neutrino and supernova neutrino physics）, the Jinping neutrino experiment will have the potential to identify the neutrinos from the CNO fusion cycles of the Sun, to cover the transition phase for the solar neutrino oscillation from vacuum to matter mixing, and to measure the geo-neutrino flux, including the Th/U ratio. These goals can be fulfilled with mature existing techniques. Efforts on increasing the target mass with multi-modular neutrino detectors and on developing the slow liquid scintillator will increase the Jinping discovery potential in the study of solar neutrinos,geo-neutrinos, supernova neutrinos, and dark matter.
