We propose a major upgrade to the existing PandaX-4T experiment at the China Jinping Underground Laboratory.The new experiment,PandaX-xT,will be a multi-ten-tonne liquid xenon,ultra-low background,and general-purpose ...We propose a major upgrade to the existing PandaX-4T experiment at the China Jinping Underground Laboratory.The new experiment,PandaX-xT,will be a multi-ten-tonne liquid xenon,ultra-low background,and general-purpose observatory.The full-scaled PandaX-xT contains a 43-t liquid xenon active target.Such an experiment will significantly advance our fundamental understanding of particle physics and astrophysics.The sensitivity of dark matter direct detection will be improved by nearly two orders of magnitude compared to the current best limits,approaching the so-called“neutrino floor”for a dark matter mass above 10 GeV/c^(2),providing a key test to the Weakly Interacting Massive Particle paradigm.By searching for the neutrinoless double beta decay of^(136)Xe isotope in the detector,the effective Majorana neutrino mass can be measured to a 10-41 meV/c^(2) sensitivity,providing a key test to the Dirac/Majorana nature of neutrinos.Astrophysical neutrinos and other ultra-rare interactions can also be measured and searched for with an unprecedented background level,opening up new windows of discovery.Depending on the findings,PandaX-xT will seek the next stage upgrade utilizing isotopic separation of natural xenon.展开更多
We report the search for neutrinoless double-beta decay of 136Xe from the PandaX-4T experiment with a 3.7-tonne natural xenon target.The data reconstruction and the background modeling are optimized in the MeV energy ...We report the search for neutrinoless double-beta decay of 136Xe from the PandaX-4T experiment with a 3.7-tonne natural xenon target.The data reconstruction and the background modeling are optimized in the MeV energy region.A blind analysis is performed with data from the commissioning run and the first science run.No significant excess of signal over the background is observed.A lower limit on the half-life of 136Xe neutrinoless double-beta decay is established to be 211024 yr at the 90%confidence level,with a 136Xe exposure of 44.6 kg yr.Our result represents the most stringent constraint from a natural xenon detector to date.展开更多
Neutrinos from core-collapse supernovae are essential for understanding neutrino physics and stellar evolution.Dual-phase xenon dark matter detectors can be used to track explosions of galactic supernovae by detecting...Neutrinos from core-collapse supernovae are essential for understanding neutrino physics and stellar evolution.Dual-phase xenon dark matter detectors can be used to track explosions of galactic supernovae by detecting neutrinos through coherent elastic neutrino-nucleus scatterings.In this study,a variation of progenitor masses and explosion models are assumed to predict neutrino fluxes and spectra,which result in the number of expected neutrino events ranging from 6.6 to 13.7 at a distance of 10 kpc over a 10-s duration with negligible backgrounds at PandaX-4T.Two specialized triggering alarms for monitoring supernova burst neutrinos are built.The efficiency of detecting supernova explosions at various distances in the Milky Way is estimated.These alarms will be implemented in the real-time supernova monitoring system at PandaX-4T in the near future,which will provide supernova early warnings for the astronomical community.展开更多
Neutron-induced nuclear recoil background is critical to dark matter searches in the PandaX-4T liquid xenon experiment.In this study,we investigate the features of neutron background in liquid xenon and evaluate its c...Neutron-induced nuclear recoil background is critical to dark matter searches in the PandaX-4T liquid xenon experiment.In this study,we investigate the features of neutron background in liquid xenon and evaluate its contribution in single scattering nuclear recoil events using three methods.The first method is fully based on Monte Carlo simulations.The last two are data-driven methods that also use multiple scattering signals and high energy signals in the data.In the PandaX-4T commissioning data with an exposure of 0.63 tonne-year,all these methods give a consistent result,i.e.,there are 1.15±0.57 neutron-induced backgrounds in the dark matter signal region within an approximated nuclear recoil energy window between 5 and 100 keV.展开更多
Signal reconstruction through software processing is a crucial component of the background and signal models in the PandaX-4T experiment,which is a multi-tonne dark matter direct search experiment.The accuracy of sign...Signal reconstruction through software processing is a crucial component of the background and signal models in the PandaX-4T experiment,which is a multi-tonne dark matter direct search experiment.The accuracy of signal reconstruction is influenced by various detector artifacts,including noise,dark count of photomultiplier,photoionization of impurities in the detector,and other relevant considerations.In this study,we presented a detailed description of a semi-data-driven approach designed to simulate a signal waveform.This work provides a reliable model for the efficiency and bias of the signal reconstruction in the data analysis of PandaX-4T.By comparing critical variables that relate to the temporal shape and hit pattern of the signals,we found good agreement between the simulation and data.展开更多
The proton-proton(pp)fusion chain dominates the neutrino production in the Sun.The uncertainty of the predicted pp neutrino flux is at the sub-percent level,whereas that of the best measurement is O(10%).In this study...The proton-proton(pp)fusion chain dominates the neutrino production in the Sun.The uncertainty of the predicted pp neutrino flux is at the sub-percent level,whereas that of the best measurement is O(10%).In this study,for the first time,we measure solar pp neutrinos in the electron recoil energy range from 24 to 144 keV using the PandaX-4T commissioning data with 0.63 tonne×year exposure.The pp neutrino flux is determined as(8.0±3.9(stat)±10.0(syst))×1010 s^(-1)cm^(-2),which is consistent with the Standard Solar Model and existing measurements,corresponding to an upper flux limit of 23.3×10^(10)s^(-1)cm^(-2)at 90%C.L..展开更多
Precise measurement of two-neutrino double beta decay(DBD)half-life is an important step for the searches of Majorana neutrinos with neutrinoless double beta decay.We report the measurement of DBD half-life of 136xe u...Precise measurement of two-neutrino double beta decay(DBD)half-life is an important step for the searches of Majorana neutrinos with neutrinoless double beta decay.We report the measurement of DBD half-life of 136xe using the Pandax-4T dual-phase Time Projection Chamber(TPC)with 3.7-tonne natural xenon and the first 94.9-day physics data release.展开更多
基金supported by the Office of Science and Technology,Shanghai Municipal Government(Grant Nos.23JC1410200,and 22JCJC1410200)the Ministry of Science and Technology of China(Grant No.2023YFA1606200)+6 种基金the National Natural Science Foundation of China(Grant Nos.1209060,12005131,11905128,11925502,12222505,and 12175139)support from Double First Class Plan of the Shanghai Jiao Tong Universitythe Tsung-Dao Lee Institute Experimental Platform Development Fundthe sponsorship from the Hongwen Foundation in Hong KongTencentNew Cornerstone Science Foundation in ChinaYangyang Development Fund。
文摘We propose a major upgrade to the existing PandaX-4T experiment at the China Jinping Underground Laboratory.The new experiment,PandaX-xT,will be a multi-ten-tonne liquid xenon,ultra-low background,and general-purpose observatory.The full-scaled PandaX-xT contains a 43-t liquid xenon active target.Such an experiment will significantly advance our fundamental understanding of particle physics and astrophysics.The sensitivity of dark matter direct detection will be improved by nearly two orders of magnitude compared to the current best limits,approaching the so-called“neutrino floor”for a dark matter mass above 10 GeV/c^(2),providing a key test to the Weakly Interacting Massive Particle paradigm.By searching for the neutrinoless double beta decay of^(136)Xe isotope in the detector,the effective Majorana neutrino mass can be measured to a 10-41 meV/c^(2) sensitivity,providing a key test to the Dirac/Majorana nature of neutrinos.Astrophysical neutrinos and other ultra-rare interactions can also be measured and searched for with an unprecedented background level,opening up new windows of discovery.Depending on the findings,PandaX-xT will seek the next stage upgrade utilizing isotopic separation of natural xenon.
基金supported by the National Key R&D Program of China(2023YFA1606200 and 2023YFA1606202)the National Natural Science Foundation of China(12090060,12090062,and U23B2070)+6 种基金the Office of Science and Technology,Shanghai Municipal Government(21TQ1400218,22JC1410100,23JC1410200,and ZJ2023-ZD-003)the support by the Fundamental Research Funds for the Central Universitiesthe sponsorship from the Chinese Academy of Sciences Center for Excellence in Particle Physics(CCEPP)Hongwen Foundation in Hong KongNew Cornerstone Science FoundationTencent Foundation in ChinaYangyang Development Fund。
文摘We report the search for neutrinoless double-beta decay of 136Xe from the PandaX-4T experiment with a 3.7-tonne natural xenon target.The data reconstruction and the background modeling are optimized in the MeV energy region.A blind analysis is performed with data from the commissioning run and the first science run.No significant excess of signal over the background is observed.A lower limit on the half-life of 136Xe neutrinoless double-beta decay is established to be 211024 yr at the 90%confidence level,with a 136Xe exposure of 44.6 kg yr.Our result represents the most stringent constraint from a natural xenon detector to date.
基金the National Natural Science Foundation of China(12090060,12090063,12105052,12005131,11905128,11925502)the Office of Science and Technology,Shanghai Municipal Government,China(22JC1410100)。
文摘Neutrinos from core-collapse supernovae are essential for understanding neutrino physics and stellar evolution.Dual-phase xenon dark matter detectors can be used to track explosions of galactic supernovae by detecting neutrinos through coherent elastic neutrino-nucleus scatterings.In this study,a variation of progenitor masses and explosion models are assumed to predict neutrino fluxes and spectra,which result in the number of expected neutrino events ranging from 6.6 to 13.7 at a distance of 10 kpc over a 10-s duration with negligible backgrounds at PandaX-4T.Two specialized triggering alarms for monitoring supernova burst neutrinos are built.The efficiency of detecting supernova explosions at various distances in the Milky Way is estimated.These alarms will be implemented in the real-time supernova monitoring system at PandaX-4T in the near future,which will provide supernova early warnings for the astronomical community.
基金Supported in part by grants from National Science Foundation of China(12090061,12005131,11905128,11925502)the Ministry of Science and Technology of China(2016YFA0400301)the Office of Science and Technology,Shanghai Municipal Government(18JC1410200)。
文摘Neutron-induced nuclear recoil background is critical to dark matter searches in the PandaX-4T liquid xenon experiment.In this study,we investigate the features of neutron background in liquid xenon and evaluate its contribution in single scattering nuclear recoil events using three methods.The first method is fully based on Monte Carlo simulations.The last two are data-driven methods that also use multiple scattering signals and high energy signals in the data.In the PandaX-4T commissioning data with an exposure of 0.63 tonne-year,all these methods give a consistent result,i.e.,there are 1.15±0.57 neutron-induced backgrounds in the dark matter signal region within an approximated nuclear recoil energy window between 5 and 100 keV.
基金supported in part by the National Science Foundation of China(12090060,12090061)Ministry of Science and Technology of China(2023YFA1606200)+1 种基金Office of Science and Technology,Shanghai Municipal Government(22JC1410100)the Double First Class Plan of the Shanghai Jiao Tong University and Guangzhou Municipal Science and Technology Project(202201010991)。
文摘Signal reconstruction through software processing is a crucial component of the background and signal models in the PandaX-4T experiment,which is a multi-tonne dark matter direct search experiment.The accuracy of signal reconstruction is influenced by various detector artifacts,including noise,dark count of photomultiplier,photoionization of impurities in the detector,and other relevant considerations.In this study,we presented a detailed description of a semi-data-driven approach designed to simulate a signal waveform.This work provides a reliable model for the efficiency and bias of the signal reconstruction in the data analysis of PandaX-4T.By comparing critical variables that relate to the temporal shape and hit pattern of the signals,we found good agreement between the simulation and data.
基金supported in part by the grants from the National Science Foundation of China(12090060,12090063,12105052,12005131,11905128,11925502)the Office of Science and Technology,Shanghai Municipal Government(22JC1410100)+6 种基金the National Science Foundation of Sichuan ProvinceChina(2024NSFSC1371)the support from the Double First Class Plan of Shanghai Jiao Tong Universitythe sponsorship from the Chinese Academy of Sciences Center for Excellence in Particle Physics(CCEPP)Hongwen Foundation in Hong KongTencentNew Cornerstone Science Foundation in China。
文摘The proton-proton(pp)fusion chain dominates the neutrino production in the Sun.The uncertainty of the predicted pp neutrino flux is at the sub-percent level,whereas that of the best measurement is O(10%).In this study,for the first time,we measure solar pp neutrinos in the electron recoil energy range from 24 to 144 keV using the PandaX-4T commissioning data with 0.63 tonne×year exposure.The pp neutrino flux is determined as(8.0±3.9(stat)±10.0(syst))×1010 s^(-1)cm^(-2),which is consistent with the Standard Solar Model and existing measurements,corresponding to an upper flux limit of 23.3×10^(10)s^(-1)cm^(-2)at 90%C.L..
基金This project is supported in part by grants from the Ministry of Science and Technology of China(No.2016YFA0400301 and 2016YFA0400302)grants from National Science Foundation of China(Nos.12090061,12090062,12005131,11905128,and 11925502)by Office of Science and Technology,Shanghai Municipal Government(grant No.18JC1410200).
文摘Precise measurement of two-neutrino double beta decay(DBD)half-life is an important step for the searches of Majorana neutrinos with neutrinoless double beta decay.We report the measurement of DBD half-life of 136xe using the Pandax-4T dual-phase Time Projection Chamber(TPC)with 3.7-tonne natural xenon and the first 94.9-day physics data release.
