Constraints on Dirac-type neutrino magnetic moments from 37Cl and Kamiokande II solar-neutrino observations.

Abstract

The different time variations of solar-neutrino observations in the $^{37}\mathrm{Cl}$ and Kamiokande II experiments are accounted for by postulating a sizable contribution from an additional electromagnetic interaction via a neutrino magnetic moment in the Kamiokande II detector. Based on the combined effects of weak and electromagnetic interactions of neutrinos, this discrepancy in the time variation provides a range of allowed values for a Dirac-type neutrino magnetic moment, $4.0l{\ensuremath{\mu}}_{{\ensuremath{\nu}}_{e}}l7.9\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}$${\mathrm{\ensuremath{\mu}}}_{\mathit{B}}$ at 95% C.L. (in units of Bohr magneton), assuming that the solar-neutrino deficit is uniform in neutrino energy.