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RE: neutrino mass



Hi all-
Ludwik asks:
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On 04 Jun 1998 "JACK L. URETSKY forwarded an interestin message about
neutrinos.
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1)
One of the three kinds of neutrinos, the muon flavor, has
been found to and reappear as it travels hundreds of
kilometers through the Earth. The energy and flight distance,
from neutrino production in the atmosphere by cosmic
radiation to the underground instrument, provide a measure
of the difference between neutrino masses.

Why "hundreds of kilometers? See below.

... Located in a specially carved out cavity in an old zinc mine
2,000 feet under Mount Ikena near Kamioka in the Japanese alps, ..
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This particular experiment selected upward going muons.

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2)
I suppose that my background is not sufficient to understand this part.

.. the functional behavior of this deficit indicates that muon
neutrinos oscillate, thus they have mass.

The conclusion is based on a theory which relates observed oscillations
to the mass. I would be more convinced if somebody was able to show
that the maximum energy of beta particles is slightly less than what
is due to the mass difference (before and after the decay). Can mass
spectroscopic data be accurate enough for such approach? We will see
when the value of the mass is announced.
=====================================================================
Ludwik Kowalski
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IF oscillations are the correct answer, then the preferred
value of the nu-mu - nu-tau mass difference is about .07 eV. The
upper limit of the nu-tau mass (from decay kinematics) is .27 MeV.
The oscillations are presumably with nu-tau because Kamioka
measures a nu-mu deficit, but no nu-e increase.
The announcement is a bit optimistic, because oscillations
have NOT, in fact, been detected, only a loss in the nu-mu flux that
seems to correlated with distance traveled through the earth.
As for Ludwik's hope for a "direct" measurement - that may
be as far off as a direct measurement of the K_long - K_short mass difference.
Regards,
Jack

"'Is it claimed that Dr. Cook's achievement is a Fact, or is it a
miracle?'
'Why so?'
'Because if it is a Miracle, any sort of evidence will answer, but
if it is a Fact, proof is necessary'"
Mark Twain, "Official Report to the I.I.A.S. (1909)