Re: neutrino mass

[harvey.picker@mail.cc.trincoll.edu (Harvey Picker)]

> According to the front page article in The New York Times the essence
> of the neutrino experiment is in the comparison of what comes from
> above with what comes from below (after traveling through Earth). The
> orientation of light cones, from the Cerenkov effect, helps to
> distinguish one direction from another.
>
> They say that the mass of the neutrino can be as large as several eV.
> This helps to answer the question about measuring it directly. Even if
> the mass of a neutrino were 100 eV, measuring it directly would be
> impossible. The accuracy of atomic mass measurements, as far as my table
> shows, is not better than several hundreds of eV. But who knows, given
> enough motivation mass spectrometrist may be able to generate more
> accurate data.
>                     Ludwik Kowalski


What these folks are looking at, presumably, are oscillations of mu
neutrinos into tau neutrinos.  The available empirical mass limits for
those two flavors of neutrinos are fairly high (of the order of MeV for the
tau neutrino, if I remember correctly).  But there is a fairly stringent
upper limit on the mass of the electron (anti-)neutrino from studies of the
energy spectrum of electrons emitted in tritium beta decays.  It's down to
a few eV, I think, and certainly less than 14 eV.

                       Harvey Picker

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