Reasearch On Solar Neutrino Experiments And Three Flavor Analysis Of Oscillation Parameters

Neutrino is one of nature's elementary particles. The existence of neutrinos was first realized by human in 1930. In order to explain the problem of continuous beta decay spectra, Pauli proposed beta decay also released some unknown particles who take a part of energy away. This new particle was called "neutron" by Pauli. When Chadwick discovered the neutron as we know it today in 1932, Ferimi dubbed the Pauli particle the "neutrino" to distinguish it from Chadwick's heavy neutron.The knowledge of neutrino was little known by human in an early study stage. It is generally recognized that neutrinos are particles with no masses, electrically neutral and weak interactions. Therefore, the neutrinos are difficult to interact with the other particles. The experiments are very difficult to detect neutrinos. The first detection of electron anti-neutrinos from reactor was made by Frederick Reines and Clyde Cowan until the year 1956. With the improvement of experimental technique, muon neutrinos and tau neutrinos are observed in the laboratory.Neutrinos are widely distributed in nature, in which neutrinos produced by solar play an important role for researchers. The first detection of solar neutrinos was Homestake made by Davis in 1968. The neutrino flux measured by experiment corresponds to approximately one third of the SSM prediction. This means a large of neutrinos lost. This is the famous the puzzle of solar neutrino problem. This puzzle was verified by SAGE, GALLEX/GNO and Super Kamiokande later. The best explanation to this puzzle is the neutrino oscillation. Neutrinos have small masses and flavor mixing. Electron neutrino flux was less than prediction for neutrino flavor transition. SNO experiment in Canada first observed all flavors of active neutrinos and not just to electron neutrinos in 2001. This is the first direct evidence for flavor transition. The long base line reactor experiment KamLAND in Japan also observed anti-neutrinos transition. The neutrino oscillation was established finally by solar neutrino and the other type experiments.Because we only find left-handed neutrino in experiments and no right-handed neutrinos, the neutrino mass is zero by standard model. The neutrino oscillation experiments show that neutrinos have different masses and mixing which conflict to prediction of standard model. It is interesting to know how the neutrinos have masses. What actually is unknown in the physical, the next breakthrough in fundamental physics maybe arise from the neutrino field. To this aim, now task is the clear understanding of neutrino oscillation and get the precision neutrino oscillation parameters:the masses and the mixing angle obtained by experimental data.Here, we first review some basic properties of neutrinos, then give the detail of neutrino oscillation in three flavor neutrino mixing frame. In vacuum we give the three flavor survival probability. In matter this is troublesome condition. We first discuss the relatively simple two flavor oscillation to give the survival probability in constant density, not constant density but adiabaticity condition medium and the MSW resonance effect. At last we give the survival probability in three flavor frame. The survival probability of solar neutrino transmitted to Earth was presented in our analysis.In the oscillation frame, the oscillation parameters to be measured are two mass differences, three mixing angles and a CP violation phase in mixing matrix. After determining the oscillation frame in neutrino experiments, the main research aim is precision measurement of these oscillation parameters. According to experiment data in present, people have already known precisely about two mass differences and two mixing angle, only mixing angleθ13 and the CP phase coupling withθ13 remain undetermined precisely. So the first aim of next generation experiments is the determination ofθ13, such as Double CHOOZ and Daya Bay neutrino experiment in China. On the basis of precision determination onθ13, one would possible to measure CP violation phase, which has an important meaning for fundamental physics, and may be an important factor that cause asymmetry between matter and antimatter in universe.Analysis of solar neutrino experimental data is the main content in this thesis. Experimental data analysis is usually used chi-square analysis. Through the combined analysis of all solar neutrino experiments and KamLAND experiment, we give the precision values of oscillation parameters Am122 andθ12 in three flavor mixing frame. The MSW resonance effect LMA region is content. We also give the result ofθ13, our hint ofθ13>0 is at 1.2σlevel. A different analysis Bayesian Probability analysis was used in this thesis. In two flavor mixing frame the Bayesian analysis result test the LMA region of solar neutrino oscillation parameters and the LMA region is very stable. In three flavor mixing frame the Bayesian analysis uses the prior probability function from the constraint of the other type neutrino experiments. We give the Bayesian result ofθ13 interval used different prior probability functions. Neutrino physics is one rising area in particle physics, only preliminary outcomes were achieved in neutrino research at present, many problems still remain unsolved. Neutrino experiments are in progress, neutrino are in depth research, how much unknown physics hidden in neutrino physical problems on earth, we are hoping more groundbreaking research outcomes arise.