The sensitivity of an experiment to detect the Majorana neutrino mass via neutrinoless double-beta decay(0νββ) strongly depends on the rate of background events that can mimic this decay. One major source of this b...The sensitivity of an experiment to detect the Majorana neutrino mass via neutrinoless double-beta decay(0νββ) strongly depends on the rate of background events that can mimic this decay. One major source of this background is the radioactive emissions from the laboratory environment. In our study, we focused on assessing the background contributions from environmental gamma rays, neutrons, and underground muons to the Jinping bolometric demonstration experiment. This experiment uses an array of lithium molybdate crystal bolometers to probe the potential 0νββ decay of the100Mo isotope at the China Jinping Underground Laboratory. We also evaluated the shielding effectiveness of the experimental setup through an attenuation study. Our simulations indicate that the combined background from environmental gamma rays, neutrons, and muons in the relevant100Mo 0νββ Q-value region can be reduced to approximately 0.003 cts/kg/keV/yr.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
We emphasize that it is extremely important for future neutrinoless double-beta(0νββ)decay experiments to reach the sensitivity to the effective neutrino mass|mββ|≈1 meV.With such a sensitivity,it is highly poss...We emphasize that it is extremely important for future neutrinoless double-beta(0νββ)decay experiments to reach the sensitivity to the effective neutrino mass|mββ|≈1 meV.With such a sensitivity,it is highly possible to discover the signals of 0νββ decays.If no signal is observed at this sensitivity level,then either neutrinos are Dirac particles or stringent constraints can be placed on their Majorana masses.In this paper,assuming the sensitivity of|mββ|≈1 meV for future 0νββ decay experiments and the precisions on neutrion oscillation parameters after the JUNO experiment,we fully explore the constrained regions of the lightest neutrino mass m1 and two Majorana-type CP-violating phases{ρ,σ}.Several important conclusions in the case of normal neutrino mass ordering can be made.First,the lightest neutrino mass is severely constrained to a narrow range m1∈[0.7,8]meV,which together with the precision measurements of neutrino mass-squared differences from oscillation experiments completely determines the neutrino mass spectrum m2∈[8.6,11.7]meV ing phases is limited to ρ∈[130°,230°],which cannot be obtained from any other realistic experiments.Third,the sum of three neutrino masses is found to beΣ≡m1+m2+m3∈[59.2,72.6]meV,while the effective neutrino mass for beta decays turns out to be mβ≡(|Ue1|2m1^2+|Ue2|2m2^2+|Ue3|2m3^2)1/2∈[8.9,12.6]meV.These observations clearly set up the roadmap for future non-oscillation neutrino experiments aiming to solve the fundamental problems in neutrino physics.展开更多
The tensor force changes the nuclear shell structure and thus may result in underlying influence of the collectivity and decay properties of the nucleus.We carefully examined the impact of the monopole and multipole e...The tensor force changes the nuclear shell structure and thus may result in underlying influence of the collectivity and decay properties of the nucleus.We carefully examined the impact of the monopole and multipole effects originating from the tensor force on both the collectivity and the matrix element for the neutrinoless double-β(0νββ)decay,using the generatorcoordinate method with an effective interaction.To analyze the effect of the tensor force,we employed an effective Hamiltonian associated with the monopole-based universal interaction that explicitly consists of the central,tensor,and spin-orbit coupling terms.The interferences among the shell structure,quadrupole collectivity,nucleon occupancy,and 0νββmatrix elements were analyzed in detail.A better understanding of the tensor force would be of great importance in reducing the theoretical uncertainty in 0νββnuclear matrix element calculations.展开更多
Nuclear matrix elements(NME) and phase space factors(PSF) entering the half-life formulas of the double-beta decay(DBD) process are two key quantities whose accurate computation still represents a challenge. In this s...Nuclear matrix elements(NME) and phase space factors(PSF) entering the half-life formulas of the double-beta decay(DBD) process are two key quantities whose accurate computation still represents a challenge. In this study, we propose a new approach of calculating these, namely the direct computation of their product as an unique formula. This procedure allows a more coherent treatment of the nuclear approximations and input parameters appearing in both quantities and avoids possible confusion in the interpretation of DBD data due to different individual expressions adopted for PSF and NME(and consequently their reporting in different units) by different authors. Our calculations are performed for both two neutrino(2 vββ) and neutrinoless(0 vββ) decay modes, for five nuclei of the most experimental interest. Further, using the most recent experimental limits for 0νββ decay half-lives,we provide new constraints on the light mass neutrino parameter. Finally, by separating the factor representing the axial-vector constant to the forth power in the half-life formulas, we advance suggestions on how to reduce the errors introduced in the calculation by the uncertain value of this constant, exploiting the DBD data obtained from different isotopes and/or decay modes.展开更多
Purpose Develop a novel charge-detecting tile for future large-scale liquid xenon TPC for searching for neutrinoless doublebeta decay.Methods Use advanced microelectronic technologies to fabricate small metal pads on ...Purpose Develop a novel charge-detecting tile for future large-scale liquid xenon TPC for searching for neutrinoless doublebeta decay.Methods Use advanced microelectronic technologies to fabricate small metal pads on a fused-silica wafer.The pads are chained into orthogonal strips,and the strips are isolated at the cross sections.The size of the pads defines the pitch between parallel strips and can be flexibly tuned according to any optimized dimension from future Monte Carlo studies.Such tile also has good potential to suppress the radioactivity and control electronics noise.Furthermore,its modular design allows to easily cover a large size.Results The design and performance have been demonstrated by a prototype tile,particularly by comprehensive tests in liquid xenon.Conclusions A new design of charge detection tile and the fabrication technologies have been developed,which would be useful for future noble liquid detectors.展开更多
基金supported in part by the State Key Research Development Program in China(Nos.2022YFA1604702 and 2022YFA1604900)the National Natural Science Foundation of China(No.12025501)Strategic Priority Research Program of Chinese Academy of Science(No.XDB34030200).
文摘The sensitivity of an experiment to detect the Majorana neutrino mass via neutrinoless double-beta decay(0νββ) strongly depends on the rate of background events that can mimic this decay. One major source of this background is the radioactive emissions from the laboratory environment. In our study, we focused on assessing the background contributions from environmental gamma rays, neutrons, and underground muons to the Jinping bolometric demonstration experiment. This experiment uses an array of lithium molybdate crystal bolometers to probe the potential 0νββ decay of the100Mo isotope at the China Jinping Underground Laboratory. We also evaluated the shielding effectiveness of the experimental setup through an attenuation study. Our simulations indicate that the combined background from environmental gamma rays, neutrons, and muons in the relevant100Mo 0νββ Q-value region can be reduced to approximately 0.003 cts/kg/keV/yr.
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supported in part by the National Key R&D Program of China(2018YFA0404100)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA10010100)+1 种基金the National Natural Science Foundation of China(11605081,11775231,11775232,11835013,11820101005)the CAS Center for Excellence in Particle Physics
文摘We emphasize that it is extremely important for future neutrinoless double-beta(0νββ)decay experiments to reach the sensitivity to the effective neutrino mass|mββ|≈1 meV.With such a sensitivity,it is highly possible to discover the signals of 0νββ decays.If no signal is observed at this sensitivity level,then either neutrinos are Dirac particles or stringent constraints can be placed on their Majorana masses.In this paper,assuming the sensitivity of|mββ|≈1 meV for future 0νββ decay experiments and the precisions on neutrion oscillation parameters after the JUNO experiment,we fully explore the constrained regions of the lightest neutrino mass m1 and two Majorana-type CP-violating phases{ρ,σ}.Several important conclusions in the case of normal neutrino mass ordering can be made.First,the lightest neutrino mass is severely constrained to a narrow range m1∈[0.7,8]meV,which together with the precision measurements of neutrino mass-squared differences from oscillation experiments completely determines the neutrino mass spectrum m2∈[8.6,11.7]meV ing phases is limited to ρ∈[130°,230°],which cannot be obtained from any other realistic experiments.Third,the sum of three neutrino masses is found to beΣ≡m1+m2+m3∈[59.2,72.6]meV,while the effective neutrino mass for beta decays turns out to be mβ≡(|Ue1|2m1^2+|Ue2|2m2^2+|Ue3|2m3^2)1/2∈[8.9,12.6]meV.These observations clearly set up the roadmap for future non-oscillation neutrino experiments aiming to solve the fundamental problems in neutrino physics.
基金supported by the National Natural Science Foundation of China(No.12275369)the Fundamental Research Funds for the Central Universities,Sun Yat-sen University(No.22qntd3101)the Guangdong Major Project of Basic and Applied Basic Research(2021B0301030006)。
文摘The tensor force changes the nuclear shell structure and thus may result in underlying influence of the collectivity and decay properties of the nucleus.We carefully examined the impact of the monopole and multipole effects originating from the tensor force on both the collectivity and the matrix element for the neutrinoless double-β(0νββ)decay,using the generatorcoordinate method with an effective interaction.To analyze the effect of the tensor force,we employed an effective Hamiltonian associated with the monopole-based universal interaction that explicitly consists of the central,tensor,and spin-orbit coupling terms.The interferences among the shell structure,quadrupole collectivity,nucleon occupancy,and 0νββmatrix elements were analyzed in detail.A better understanding of the tensor force would be of great importance in reducing the theoretical uncertainty in 0νββnuclear matrix element calculations.
基金Supported by Ministry of Research and Innovation through UEFISCDI,project PCE-2016-0078,contract 198/2017
文摘Nuclear matrix elements(NME) and phase space factors(PSF) entering the half-life formulas of the double-beta decay(DBD) process are two key quantities whose accurate computation still represents a challenge. In this study, we propose a new approach of calculating these, namely the direct computation of their product as an unique formula. This procedure allows a more coherent treatment of the nuclear approximations and input parameters appearing in both quantities and avoids possible confusion in the interpretation of DBD data due to different individual expressions adopted for PSF and NME(and consequently their reporting in different units) by different authors. Our calculations are performed for both two neutrino(2 vββ) and neutrinoless(0 vββ) decay modes, for five nuclei of the most experimental interest. Further, using the most recent experimental limits for 0νββ decay half-lives,we provide new constraints on the light mass neutrino parameter. Finally, by separating the factor representing the axial-vector constant to the forth power in the half-life formulas, we advance suggestions on how to reduce the errors introduced in the calculation by the uncertain value of this constant, exploiting the DBD data obtained from different isotopes and/or decay modes.
基金Program of International S&T Cooperation of MoST(2015DFG02000)CAS-IHEP Fund for PRC-US Collaboration inHEP,CAS Center for Excellence in Particle Physics(CCEPP).
文摘Purpose Develop a novel charge-detecting tile for future large-scale liquid xenon TPC for searching for neutrinoless doublebeta decay.Methods Use advanced microelectronic technologies to fabricate small metal pads on a fused-silica wafer.The pads are chained into orthogonal strips,and the strips are isolated at the cross sections.The size of the pads defines the pitch between parallel strips and can be flexibly tuned according to any optimized dimension from future Monte Carlo studies.Such tile also has good potential to suppress the radioactivity and control electronics noise.Furthermore,its modular design allows to easily cover a large size.Results The design and performance have been demonstrated by a prototype tile,particularly by comprehensive tests in liquid xenon.Conclusions A new design of charge detection tile and the fabrication technologies have been developed,which would be useful for future noble liquid detectors.
