We analyze the existed solar neutrino experiment data and show the allowed regions. The result from SNO's salt phase itself restricts quite a lot the allowed region's area. Reactor neutrinos play an important role in determining oscillation parameters. KamLAND gives decisive conclusion on the solution to the solar neutrino puzzle, in particular, the spectral distortion in the 766.3 Ty KamLAND data gives another new improvement in the constraint of solar MSW-LMA solutions. We confirm that at 99.73% C.L. the high-LMA solution is excluded. * email: qiuyu@ustc.edu.cn 1 I IntroductionThe electron neutrinos emitted from the sun disappear somewhere when they travel to the earth. This is the famous solar neutrino deficit, which is the almost forty years' "Solar Neutrino Problem".There were many attempts to solve this puzzle during the years. Some of them were tried to modify the solar model in order to give a lower original neutrino flux, which conflict the energy spectrum provided by the 4 first-generation experiments: Homestake, Sage, Gallex and Kamiokande [1,2,3,4]. Recent experiments have shown that the solar neutrino oscillate by ν e → ν µ,τ inside the sun via MSW conversions. This was proven by the Sudbury Neutrino Observatory (SNO) [5], and it was confirmed by the reactor experiment KamLAND [6]. The former experiment detects ν e , ν e + ν µ + ν τ and ν e + 15%(ν µ + ν τ ) three quantities on earth, which correspond to CC, NC and ES interactions respectively; KamLAND observes II Solar neutrinosThe solar neutrino puzzle was solved by the neutrino oscillations ν e → ν µ,τ inside the sun via MSW conversions. This was proved by the Sudbury Neutrino Observatory (SNO) in Canada. And it was confirmed by the laboratory base line experiment KamLAND in Japan.SNO is a 1000 ton heavy water Cerenkov detector mainly measuring 8 B solar neutrinos. It consists of nearly 9450 photon-multiplier tubes and light concentrator units arrayed on a geodesic support structure, with light water surrounding the spherical acrylic vessel containing the D 2 O.The first phase of SNO data is from the pure D 2 O. After that the experimenters add up N aCl (salt) 2 to enhance the NC events rates. This is called the second phase or "salt phase".In analysis of the solar oscillation data [7], we use the χ 2 defined as:where χ 2 1gen stands for Chlorine and Gallium experiments. To calculate each individual chi square in the right hand side of eq. (2.1), we use the so called covariance approach:Here R exp n and R theo n correspond to experimental result and theoretical value for the n-th data point. N=2,34,44 are for χ 2 1gen , χ 2 SK , χ 2 SN O respectively. For getting a R theo n , the important step is to calculate the ν e survival probability. We have used three methods to check its consistency:the Parke formula [8]; the modified semi-analytic formula in [9]; and the completely numerical propagation. We found that the second way is the best, considering both the calculation precision and the computer CPU hour.The covariant matrix of squared ...
Reactor neutrinos play an important role in determining parameter θ 13 in the lepton mixing (PMNS) matrix. A next important step on measuring PMNS matrix could be to build another reactor neutrino experiment, for example, DaYa Bay in China, to search the possible oscillations via sin 2 2θ 13 and ∆m 2 13 . We consider 4 different schemes for positions of three 8-ton detectors of this experiment, and simulate the results with respect to an array of assumed "true" values of physics parameters. Using three kinds of analysis methods, we suggest a best scheme for this experiment which is to place a detector 2200m ∼ 2500m symmetrically away from two reactors, and to put the other two detectors closer to their corresponding reactors respectively, almost at a 100m ∼ 200m distance. Moreover, with conservative assumption on the experimental technique, we construct series of allowed regions from our simulation results, and give detailed explanations therein. * email: qiuyu@ustc.edu.cn 1 I IntroductionAn next step in the exciting field of neutrino physics would be to improve current measurements and to measure some of the remaining unknown parameters in the full 3 × 3 leptonic flavor mixing, which is called the PMNS mixing matrix. There are important differences between the PMNS and quark CKM matrices. Which may be essential for our understanding the underlying physics.In addition to three masses m i , there are 6 free parameters in the matrix. We may parameterize U P M N S [1] as follows:(1.1) The CHOOZ experiment [7,8] only gives an upper limit on the mixing angle θ 13 (sin 2 2θ 13 < 0.10 at 90% confidence level). There are attempts to find this mixing angle in LBL accelerator experiments [5,6], or in three neutrino analysis of solar neutrino [6,9,10], but the precision is very difficult to achieve. Since ∆m 2 12 ≪ ∆m 2 23 , it must happen that ∆m 2 13 ≈ ∆m 2 23 . A new generation of reactor experiments has been proposed to search forν e disappearance at baselines of 1 ∼ 2 km corresponding to this value of ∆m 2 . To improve on the mixing angle sensitivity achieved by PaloVerde and CHOOZ, proposals for reactor θ 13 experiments include a large detector to reduce the statistical error, and also a second detector positioned very close (∼ 100 m) to the reactor. The near detector would precisely measure the incident flux, providing to drop out many systematic uncertainties in the flux calculation. This also requires the detectors to be made identical and/or movable. Sensitivity down to sin 2 2θ 13 ≈ 10 −2 seems within grasp. Such experiments were discussed in literature [11,12]. A practical possibility is a reactor experiment at DaYa-Bay, which is located near a special economic zone in Guang-Dong Province in southern China. There are nuclear power plants in that area.The knowledge we have about neutrino mixing is powerful to judge Grand Unified models, such as the most inspiring SO(10) GUT. Starting from the lepton quark symmetry in this model, one is able to obtain a bi-large neutrino mixing pattern via see-saw mechani...
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