Report of the APS Neutrino Study Reactor Working Group

Abouzaid, E. ; Anderson, K. ; Barenboim, G. ; Berger, B. ; Blucher, E. ; Bolton, T. ; Choubey, S. ; Conrad, J. ; Formaggio, J. ; Freedman, S. ; Finely, D. ; Fisher, P. ; Fujikawa, B. ; Gai, M. ; Goodman, M. ; de Goueva, A. ; Hadley, N. ; Hahn, R. ; Horton-Smith, G. ; Kadel, R. ; Kayser, B. ; Heeger, K. ; Klein, J. ; Learned, J. ; Lindner, M. ; Link, J. ; Luk, K.-B. ; McKeown, R. ; Mocioiu, I. ; Mohapatra, R. ; Naples, D. ; Peng, J. ; Petcov, S. ; Pilcher, J. ; Rapidis, P. ; Reyna, D. ; Shaevitz, M. ; Shrock, R. ; Stanton, N. ; Stefanski, R. ; Yamamoto, R. ; Worcester, M.

Lawrence Berkeley National Laboratory

关键词: Magnetic Moments;    43 Particle Accelerators;    Neutrino Reactor Oscillation Experiment Theta13 Aps;    Sensitivity;    Neutrinos;   

DOI  :  10.2172/834324
RP-ID  :  LBNL--56599
RP-ID  :  AC03-76SF00098
RP-ID  :  834324

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来源: UNT Digital Library

【 摘 要 】

The worldwide program to understand neutrino oscillations and determine the neutrino mixing parameters, CP violating effects, and mass hierarchy will require a broad combination of measurements. The group believes that a key element of this future neutrino program is a multi-detector neutrino experiment (with baselines of {approx} 200 m and {approx} 1.5 km) with a sensitivity of sin{sup 2} 2{theta}{sub 13} = 0.01. In addition to oscillation physics, the reactor experiment may provide interesting measurements of sin{sup 2} {theta}{sub W} at Q{sup 2} = 0, neutrino couplings, magnetic moments, and mixing with sterile neutrino states. {theta}{sub 13} is one of the twenty-six parameters of the standard model, the best model of electroweak interactions for energies below 100 GeV and, as such, is worthy of a precision measurement independent of other considerations. A reactor experiment of the proposed sensitivity will allow a measurement of {theta}{sub 13} with no ambiguities and significantly better precision than any other proposed experiment, or will set limits indicating the scale of future experiments required to make progress. Figure 1 shows a comparison of the sensitivity of reactor experiments of different scales with accelerator experiments for setting limits on sin{sup 2} 2{theta}{sub 13} if the mixing angle is very small, or for making a measurement of sin{sup 2} 2{theta}{sub 13} if the angle is observable. A reactor experiment with a 1% precision may also resolve the degeneracy in the {theta}{sub 23} parameter when combined with long-baseline accelerator experiments. In combination with long-baseline measurements, a reactor experiment may give early indications of CP violation and the mass hierarchy. The combination of the T2K and Nova long-baseline experiments will be able to make significant measurements of these effects if sin{sup 2} 2{theta}{sub 13} > 0.05 and with enhanced beam rates can improve their reach to the sin{sup 2} 2{theta}{sub 13} > 0.02 level. If {theta}{sub 13} turns out to be smaller than these values, one will need other strategies for getting to the physics. Thus, an unambiguous reactor measurement of {theta}{sub 13} is an important ingredient in planning the strategy for the future neutrino program.