| The Neutrino Oscillation is the only observed phenomenon beyond the standard model of particle physics,which can be interpreted in the framework of three neutrino mixings.It is governed by three mixing angles(?12,?23,?13),two mass-squared differ-ences(?m122,?m322)and one leptonic CP-violating phase ?.Studies of the solar neutrino problem and the atmospheric neutrino anomaly confirmed the discovery of neutrino os-cilation and measured ?12,?23,?m122,|?m322|.Unknown parameters were the value of?13,the mass ordering of v2 and v3,and the value of ? before the year of 2012.As clean sources of electron antineutrinos,reactors can provide enormous antineutrinos to measure former two parametersDaya Bay Reactor Neutrino Experiment measures the disappearance probability of electron antineutrinos emitted from the daya bay nuclear power plant.Daya Bay measured a non-zero value of ?13 with a significance of 5.2 standard deviation using IBD candidates observed over 55 days of data collection.It indicates the discovery of the third oscillation mode for the first time.Daya Bay observed 3.5 million electron antineutrino signals in near detectors and 0.5 million in far detectors over 1958 days of stable operation on 30 August 2017.This is the largest data sample of reactor neutrinos in the world.This thesis analyzed neutrino data collected by the Daya Bay experiment Measured prompt spectra were obtained by selection of antineutrino signals,including time dependent accidental backgrounds,muon veto and multiplicity cut efficiency.Pre-dicted prompt spectra were calculated according to neutrino spectra from reactors and the response matrix of the detector.A ?2 function was constructed combining mea-sured and predicted prompt spectra,which incorporated the 6+8+7AD configuration of detectors.The minimization of the ?2 functions gave sin2 2?13=0.0860±0.0023(stat)±0.0016(syst),and ?m322=[2.4648±0.0472(stat)±0.0507(syst)]× 10-3 eV2 under the assumption of normal ordering.Total uncertainties are 3.4%and 2.8%,which include 60%and 50%contribution from statistics respectively.The precision of sin2 2?13 keeps to be world-leading,and that of |?m322| is comparable with the results from accelerator neutrino experimentsJiangmen Underground Neutrino Observatory measures neutrino mass ordering by the interference of two oscillation modes induced by two mass-squared differences JUNO is expected to acquire 10 thousand reactor neutrino events after 6 years oper-ation.It can determine the neutrino mass ordering at a significance of 3?4?.JUNO requires an unprecedented energy resolution to be 3%/?(MeV)in order to distin-guish the distortion of neutrino spectra caused by neutrino mass ordering.This thesis developed a new energy reconstruction algorithm with limited calibration data,which is independent of the optical model of the detector.It shows that the non-uniformity of reconstructed energies can be controlled within±1%.Then,this thesis studied the application of light concentrators in JUNO.Light concentrators can compensate the loss of photons due to the increase of PMT clearance.And they can decrease the residual non-uniformity of the detector,which is helpful to decrease the non-statistical term of energy resolution.At last,this thesis measured the characteristics of linear alkylbenzene,which is the solvent of JUNO's liquid scintillator.The Rayleigh scatter-ing length is measured with an absolute method.In a detector with 4? solid angle,Rayleigh scattering length is important to the photoelectron yield.It can affect the statistical term of energy resolution.The Rayleigh scattering length is measured to be 27.1±0.9(stat.)± 1.7(syst.)m at 432 nm wavelength and the room temperature.It indicates the transparence of liquid scintillator is good enough for achieving required energy resolution.The diffusivity and specific heat capacity of linear alkylbenzene were measured at room temperature.The conductivity,heat capacity ratio,and speed of sound were derived from our measurements based on thermodynamic relations,which are important reference data for liquid scintillator filling and the positioning of the calibration system. |
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