Research On Neutrino Experiments And Analysis Of The Oscillation Parameters

In early universe,neutrinos were produced in the Big Bang.They are most ubiquitous particles in the universe.Neutrinos are elementary particles with tiny masses,electrically neutral,and weak interactions.Most of the neutrinos exist due to its small cross section.Except the neutrinos produced in the Big Bang,neutrinos are copiously produced in natural sources:in the supernova,in the burning of the stars,in the interaction of cosmic rays and in the beta decay of the matters in earth.Neutrino is hard to be detected for its weak interaction with matter.Therefore,our knowledge of neutrino is still very shallow.It is already more than seventy years since Pauli postulated the existence of neutrinos.But neutrino is still a lingering problem in the minds of scientists.Now we know that there exists three generations of neutrinos.The electron neutrino was observed at the first time in the reactor experiment in 1956.The pioneering Homestake experiment is a radiochemical experiment which detected the solar neutrinos.The first data of the Homestake experiment indicated that the solar neutrino flux on the Earth was significantly smaller than that predicted by the SSM.A series of experiments are in agreement with that measured in Homestake.One of the possible explanations is neutrino oscillation mechanism.Solar electron neutrino may be converted into other flavor neutrino on their way from the Sun to the Earth.There are also many other hypothesizes to solve this problem.Preliminary experiments could only confirm the deficit of solar electron neutrinos.But we don't know whether it is because of neutrino oscillation.A significantly progress of Solar Neutrino Problem was made since 2001.The new generation solar neutrino experiments SNO is a 1000-tonne heavy water Cherenkov detector.It can make simultaneous measurements of the flux of all active flavor neutrinos.It would provide the evidence of the disappearance of the electron neutrino and the production ofν_μ.ν_Ï„.The total flux of three active neutrinos is agreement with the prediction of SSM given by John Bahcall.The neutrino oscillation mechanism is turn out to be the most natural and reasonable solution of the SNP although other solution can't be excluded absolutely. The KamLAND reactor neutrino experiment is the first experiment that observes reactor antineutrino disappearance.There are 40 percent of the reactor neutrino disappeared.It conclusively demonstrated the neutrino flavor transformation.Now we can confirm that solar neutrino is converted to other flavor neutrinos,and neutrino oscillation occurrs.The mixing angle is large.It is important that neutrino is massive. Some modification should be made into the Standard Model.It can indicate the existence of new physics beyond the Standard Model such as lepton number violation, proton decay etc.Neutrino physics become an important direction in recent years.Neutrino is a very mysterious particle.We get more and more knowledge about neutrino since the oscillation mechanism is confirmed.To analyze the neutrino experiment data and give the estimate interval of the oscillation parameters is one of the important directions in neutrino research.We first review the neutrino mass in particle physics.We talk about the Dirac mass,Majorana mass and the general case of Dirac-Majorana mass.And we give a detailed description on neutrino oscillation.In the simple case of two flavor neutrino oscillation,we derive the survival probability in vacuum and in matter.We mainly derive the oscillation formula in the uniform matter and in the adiabatic approximation case,especial the MSW mechanism.We analyze the experiment data by the oscillation mechanism.Both the traditional least-squares analysis and the Bayesian analysis are use in our analysis.And the estimate interval in our analysis confirms the LMA MSW adiabatic solution for SNP.And we even exclude several other hypothesises on oscillation model by the special character of Bayesian analysis.This significantly proves the LMA solution.In our conclusion,the LMA solution is stable and reliable.Through.the analysis of the solar neutrino experiments and the atmospheric neutrino experiments,we have known four parameters of the total six absolute parameters in the PMNS mixing matrix.There are still two parameters unknown.One of them is the most important parameter,CP violation phase.The CP phase is always associated withθ₁₃,so the detection ofθ₁₃ is more important in the next generation experiments.We can detect the CP violation effect and study the hypostasis of CP violation only if we complete the detection ofθ₁₃.So the detection ofθ₁₃is significantly to the study of the flavor physics.An precise detection ofθ₁₃will greatly enhance our knowledge about the secondary effect of the solar,atmosphere and long base line neutrino oscillation but also will help us to study supernova neutrino oscillation problems.A practical possibility is a reactor experiment at DaYa-Bay,which is located in Guang Dong Province in southern China.We explain different methods of analysis and importantly, arrangements of the detectors' positions accompanied by our simplified simulations on the possible sensitivity regions.Furthermore we suggest a more potential setting for the Da Ya Bay experiment.In our analysis,the experiment will be able to discover a sin² 2θ₁₃greater than 0.02.The Da Ya Bay experiment is simply,has no technical difficulty and has suitable experiment circumstance.It is a very feasible reactor experiment.With improvement in technology and better budget the sensitivity can be even better.In current research,neutrino physics is the forefront of the particle physics, astrophysics and cosmology.In recent years,a series of major achievements in neutrino physics indicate the important progress in particle physics.Neutrino physics is still in a period of great development.Neutrino is the lightest elementary particle and is the final product in all particle decays.Neutrinos have small but finite masses. They may in fact be a sizable fraction of hot dark matter and are great in relevant to the formation of the universe structure.The CP violation in neutrino oscillation may play a fundamental role in understanding the matter and antimatter asymmetry in our universe.At the same time,neutrinos carry with much information of the orb. Neutrino is electrically neutral,so it would not be deflected in the magnetic field and not be blocked by matter like charged particles.Also it will not interact with the CMB like charged particle and photon.So used neutrinos to probe the depths of the universe will greatly promote the development of astronomy.The survival probability of neutrino oscillation is affected by the density of material in the trajectory.So we can measure the density of the materials where neutrinos passed through to obtain the internal information of sun and the earth.Along with the development of science,we may get more and more knowledge and understanding of neutrinos.