The Jiangmen Underground Neutrino Observatory(JUNO)features a 20 kt multi-purpose underground liquid scintillator sphere as its main detector.Some of JUNO's features make it an excellent location for^8B solar neut...The Jiangmen Underground Neutrino Observatory(JUNO)features a 20 kt multi-purpose underground liquid scintillator sphere as its main detector.Some of JUNO's features make it an excellent location for^8B solar neutrino measurements,such as its low-energy threshold,high energy resolution compared with water Cherenkov detectors,and much larger target mass compared with previous liquid scintillator detectors.In this paper,we present a comprehensive assessment of JUNO's potential for detecting^8B solar neutrinos via the neutrino-electron elastic scattering process.A reduced 2 MeV threshold for the recoil electron energy is found to be achievable,assuming that the intrinsic radioactive background^(238)U and^(232)Th in the liquid scintillator can be controlled to 10^(-17)g/g.With ten years of data acquisition,approximately 60,000 signal and 30,000 background events are expected.This large sample will enable an examination of the distortion of the recoil electron spectrum that is dominated by the neutrino flavor transformation in the dense solar matter,which will shed new light on the inconsistency between the measured electron spectra and the predictions of the standard three-flavor neutrino oscillation framework.IfDelta m^(2)_(21)=4.8times10^(-5);(7.5times10^(-5))eV^(2),JUNO can provide evidence of neutrino oscillation in the Earth at approximately the 3sigma(2sigma)level by measuring the non-zero signal rate variation with respect to the solar zenith angle.Moreover,JUNO can simultaneously measureDelta m^2_(21)using^8B solar neutrinos to a precision of 20% or better,depending on the central value,and to sub-percent precision using reactor antineutrinos.A comparison of these two measurements from the same detector will help understand the current mild inconsistency between the value of Delta m^2_(21)reported by solar neutrino experiments and the KamLAND experiment.展开更多
The high energy cosmic-radiation detection(HERD)facility is a space mission designed for detecting cosmic ray(CR)electrons,γ-rays up to tens of TeV and CR nuclei from proton to iron up to several PeV.The main instrum...The high energy cosmic-radiation detection(HERD)facility is a space mission designed for detecting cosmic ray(CR)electrons,γ-rays up to tens of TeV and CR nuclei from proton to iron up to several PeV.The main instrument of HERD is a 3-D imaging calorimeter(CALO)composed of nearly ten thousand lutetium yttrium orthosilicate(LYSO,with cerium doping)crystal cubes.A large dynamic range of single HERD CALO Cell(HCC)is necessary to achieve HERD’s PeV observation objectives,which means that the response of HCC should maintain a good linearity from minimum ionizing particle(MIP)calibration to PeV shower maximum.In order to study the linearity ofHCC over such a large energy range,a beam test has been implemented at the E2 and E3 beam lines of BEPC.High intensity pulsed electron beam provided by E2 line is used for producing high energy density within HCC;π^(+)/proton provided by E3 line are used forHCCcalibration.The results showthat no saturation effect occurs and the linearity ofHCCis better than 10%from 30 MeV(1MIP)to 1.1×10^(3) TeV(energy density is 93 TeV/cm^(3)),which can meet the requirement mentioned above.展开更多
Background The linear alkylbenzene has been recently used as the solvent of liquid scintillator by several neutrino experiments.The nonlinear energy response induced by the ionization quenching is critical in this kin...Background The linear alkylbenzene has been recently used as the solvent of liquid scintillator by several neutrino experiments.The nonlinear energy response induced by the ionization quenching is critical in this kind of detectors.An empirical model proposed by Birks is commonly used to describe the quenching effect;however,recently,the parameter kB in the model is found to be particle dependent.Purpose To improve the understanding of proton quenching in LS detectors.Methods A 14 MeV D–T compact neutron generator is deployed which can provide recoil protons with kinetic energies ranging from 0.5 to 13 MeV in LS.Results The parameter kB is extracted by fitting the data to the Birks’law prediction with careful examination of systematic uncertainties.Conclusion The measurement will contribute to the in-depth understanding of the energy nonlinearity in liquid scintillator detectors.展开更多
基金This work was supported by the Chinese Academy of Sciences,the National Key R&D Program of China,the CAS Center for Excellence in Particle Physics,the Joint Large Scale Scientific Facility Funds of the NSFC and CAS,Wuyi University,and the Tsung-Dao Lee Instiute of Shanghai Jiao Tong University in China,the In stiut National de Physique Nucleaire et de Physique de Particules(IN2P3)in France,the Istituto Nazionale di Fisica Nucleare(INFN)in Italy,the Fond de la Recherche Scintifique(F.R.S-FNRS)and FWO under the"Excellence of Science-EOS"in Belgium,the Conselho Nacional de Desenvolvimento Cientificoce Tecnologico in Brazil,the Agencia Nacional de Investigacion y Desrrollo in Chile,the Charles University Research Centre and the Ministry of Education,Youth,and Sports in Czech Republic,the Deutsche Forschungsgemeinschaft(DFG),the Helmholtz Association,and the Cluster of Exellence PRISMA+in Germany,the Joint Institute of Nuclear Research(JINR),Lomonosov Moscow State University,and Russian Foundation for Basic Research(RFBR)in Russia,the MOST and MOE in Taiwan,the Chu-lalongkorm University and Suranaree University of Technology in Thailand,and the University of aliformia at Irvine in USA.
文摘The Jiangmen Underground Neutrino Observatory(JUNO)features a 20 kt multi-purpose underground liquid scintillator sphere as its main detector.Some of JUNO's features make it an excellent location for^8B solar neutrino measurements,such as its low-energy threshold,high energy resolution compared with water Cherenkov detectors,and much larger target mass compared with previous liquid scintillator detectors.In this paper,we present a comprehensive assessment of JUNO's potential for detecting^8B solar neutrinos via the neutrino-electron elastic scattering process.A reduced 2 MeV threshold for the recoil electron energy is found to be achievable,assuming that the intrinsic radioactive background^(238)U and^(232)Th in the liquid scintillator can be controlled to 10^(-17)g/g.With ten years of data acquisition,approximately 60,000 signal and 30,000 background events are expected.This large sample will enable an examination of the distortion of the recoil electron spectrum that is dominated by the neutrino flavor transformation in the dense solar matter,which will shed new light on the inconsistency between the measured electron spectra and the predictions of the standard three-flavor neutrino oscillation framework.IfDelta m^(2)_(21)=4.8times10^(-5);(7.5times10^(-5))eV^(2),JUNO can provide evidence of neutrino oscillation in the Earth at approximately the 3sigma(2sigma)level by measuring the non-zero signal rate variation with respect to the solar zenith angle.Moreover,JUNO can simultaneously measureDelta m^2_(21)using^8B solar neutrinos to a precision of 20% or better,depending on the central value,and to sub-percent precision using reactor antineutrinos.A comparison of these two measurements from the same detector will help understand the current mild inconsistency between the value of Delta m^2_(21)reported by solar neutrino experiments and the KamLAND experiment.
基金This research was supported by National Natural Science Foundation of China,Grant No.11327303,11473028 and 11675196International Science and Technology Cooperation Program of China,Grant No.2015DFA10140+3 种基金Interdisciplinary Innovation Team Project of Chinese Academy of Sciences(Research Team of The High Energy cosmic-Radiation Detection)Qianren start-up,Grant No.292012312D1117210Strategic Pioneer Program in Space Science,Chinese Academy of Sciences,Grant No.XDA04075600Youth Innovation Promotion Association of CAS,Grant No.2014009.The authors would like to thank Dr.Sun Jianchao,Dr.Zhang Xuan,Dr.Zhang Xiaofeng and Dr.Ning Zhe for their support.
文摘The high energy cosmic-radiation detection(HERD)facility is a space mission designed for detecting cosmic ray(CR)electrons,γ-rays up to tens of TeV and CR nuclei from proton to iron up to several PeV.The main instrument of HERD is a 3-D imaging calorimeter(CALO)composed of nearly ten thousand lutetium yttrium orthosilicate(LYSO,with cerium doping)crystal cubes.A large dynamic range of single HERD CALO Cell(HCC)is necessary to achieve HERD’s PeV observation objectives,which means that the response of HCC should maintain a good linearity from minimum ionizing particle(MIP)calibration to PeV shower maximum.In order to study the linearity ofHCC over such a large energy range,a beam test has been implemented at the E2 and E3 beam lines of BEPC.High intensity pulsed electron beam provided by E2 line is used for producing high energy density within HCC;π^(+)/proton provided by E3 line are used forHCCcalibration.The results showthat no saturation effect occurs and the linearity ofHCCis better than 10%from 30 MeV(1MIP)to 1.1×10^(3) TeV(energy density is 93 TeV/cm^(3)),which can meet the requirement mentioned above.
基金National Natural Science Foundation of China(Grant Nos.11390381 and 11225525).
文摘Background The linear alkylbenzene has been recently used as the solvent of liquid scintillator by several neutrino experiments.The nonlinear energy response induced by the ionization quenching is critical in this kind of detectors.An empirical model proposed by Birks is commonly used to describe the quenching effect;however,recently,the parameter kB in the model is found to be particle dependent.Purpose To improve the understanding of proton quenching in LS detectors.Methods A 14 MeV D–T compact neutron generator is deployed which can provide recoil protons with kinetic energies ranging from 0.5 to 13 MeV in LS.Results The parameter kB is extracted by fitting the data to the Birks’law prediction with careful examination of systematic uncertainties.Conclusion The measurement will contribute to the in-depth understanding of the energy nonlinearity in liquid scintillator detectors.
