AAS Meeting #193 - Austin, Texas, January 1999
Session 100. The Quiet and Active Sun
Display, Saturday, January 9, 1999, 9:20am-4:00pm, Exhibit Hall 1

## [100.05] MSW Time Variations of the Solar Neutrino flux

L.M. Malyshkin, R.M. Kulsrud (Princeton University Observatory)

We consider the possibility of MSW time variations of the solar neutrino flux due to neutrino interference effects. For two types of neutrinos there are two MSW neutrino solutions, + and -. In vacuum these are the m1 and m2 (m12) mass neutrino states. These two neutrino states have propagation time delays relative to light, t+ and t-, due to nonzero rest masses. Let \sigmat\equiv\hbar/|t+-t-|. The energy difference of the two states is \sigmaa={\cal E}\,a|t+-t-|/c, where {\cal E} is the emitted neutrino energy, and a is the acceleration of the emitting nucleus.

Two necessary criteria to observe neutrino flux time variations are proposed. The first criterion, \sigma{{\lower.5ex\;\buildrel{\mbox{\footnotesize<}}\over{\mbox{\footnotesize\sim}}\;}}\sigmat, for the time variation not to be averaged to zero over the detection energy width \sigma, should be satisfied. In the case of the 0.862\,{\rm Mev} 7Be solar neutrino line this criterion gives us an upper estimate for m22-m12, the difference of neutrino mass squared, of ~ 10-9{\rm ev}2. The second criterion, \sigmaa{{\lower.5ex\;\buildrel{\mbox{\footnotesize<}}\over{\mbox{\footnotesize\sim}}\;}}\sigmat, is necessary for collisional coherence to exist. This criterion is equivalent to a plausible condition a|t+2-t-2|{{\lower.5ex\;\buildrel{\mbox{\footnotesize<}}\over{\mbox{\footnotesize\sim}}\;}} {{\!\,\lambda\!\!\!\!\!\stackrel{-}{\phantom{__}}\!\,}}. Our criterion is stronger than collisional coherence criteria formerly suggested, which are roughly equivalent to the condition a|t+2-t-2|{{\lower.5ex\;\buildrel{\mbox{\footnotesize<}}\over{\mbox{\footnotesize\sim}}\;}} l, because the neutrino De Broglie wavelength {{\!\,\lambda\!\!\!\!\!\stackrel{-}{\phantom{__}}\!\,}} is much less than the interparticle distance in the solar interior l.

Exact values for the detected neutrino flux and its variations will be presented for both the case of a solar neutrino line, and the case of a continuous neutrino spectrum with a Gaussian shape of the energy response function of the neutrino detection device.