Neutrino Oscillations

This post is a followup to comments made by Bjoern Feuerbacher in another
thread. The other thread was getting terribly long - and was on another
subject (the book, The Big Bang Never Happened, and Ned Wright's webpage on
same).


Bjoern:
"Neutrino oscillations are clear evidence for neutrino masses."

greywolf42:
Neutrino 'oscillations' are postulated to explain a discrepancy between
theory and observation.

Bjoern:
When you say "theory", do you mean the standard solar model?

No. I mean the theory of the operation of the SuperK and neutrinos that
pass through the Earth.

If yes,
then you are wrong - neutrino oscillations weren't postulated only
because of the observations of solar neutrinos which contradicted this
model.

Good thing that I wasn't referring to the solar model.

And today, this discrepancy has disappeared: when measuring *all*
neutrinos (the SNO measurements), it turns out that the result agrees
well with the predictions of the solar model.

That wouldn't explain the discrepancies that *existed* in other detectors.

Got a reference for 'the SNO measurements'? My detailed information was all
design (1993, "Neutrino Astrophysics," Bahcall).

In 1997, "Unsolved Problems in Astrophysics," Bahcall and Ostriker, ed,
there are "three solar neutrino problems:"
1) Calculated versus observed chlorine rate,
2) Incompatibility of Chlorine and Water (Kamiokande) experiments,
3) Gallium experiments: No room for 7Be neutrinos.


Bjoern:
"Do you have another explanation for neutrino oscillations which fits all of
the data?"

greywolf42:
"Neutrino oscillations ARE a theoretical explanation. Not data."

Bjoern:
"O.k., then let's word it in another way: Do you have another explanation,
besides neutrino oscillations, for the
experimental facts that 1) Superkamiokande measured more atmospheric
neutrinos from above than from below, with a systematic dependence on zenith
angle, and 2) the total neutrino flux from the sun matches nicely the
predicted electron neutrino flux from the standard solar model? There are
some more experiments which show similar things, but these are the best
known."

I think you somehow garbled #2. Read it again, and let me know if you
really meant it just that way.

Let's limit the discussion to the SuperK (#1), for now.

Be advised that my understanding of the SuperK experiments on 'neutrino
oscillation' comes solely from a Scientific American article, a couple of
years back. I haven't stirred myself to more serious study of the
experiment. I'd appreciate hearing your personal favorite reference of
same, so that we can work from the same pages.

My primary recollections of the experimental problems in SuperK were as
follows:

1) The discrimination between an electron Cerenkov ring and a muon Cerenkov
right was totally subjective (qualitative, not quantitative). Narrow rings
(those with a vertex originating near the detection wall) would be almost
impossible to differentiate. The dependence of the result upon this
discrimination was quite strong. Should this human discrimination be in
error by as much as only 10% (which is easy to do) the 'effect' would have
disappeared.

2a) The dependence on zenith angle was assumed to mark a difference in
distance travelled through the Earth. But the curve did not follow the
curve that would be expected with increasing distance -- it followed an
angular dependence that indicated an instrument effect.

2b) This dependence on angle is the one that one would expect if there were
some difference in sensitivity of the detectors to angle or location in the
tank. Such as depth, or some other difference between top and bottom of the
tank. The pressure of the fluid at the top of the SuperK is several times
less than the pressure in the bottom of the tank. Which could have resulted
in bubbles messing with the discrimination between electron and muon
signatures.

In short, my current view is that the SuperK 'neutrino oscillations' are
observer or instrument artifacts.


Before we get into explaining "all the data," I want you to identify the
specific model that YOU claim explains it all. Per Bahcall (1997),

"Theoretical physicists have fertile imaginations; they have provided us
with a smorgasbord of explanations based upon new particle physics,
including vacuum neutrino oscillations, resonant oscillations in matter (the
MSW effect), resonant magnetic-moment transitions, sterile neutrinos,
neutrino decay, and violation of the equivalence principel by neutrinos.
Most of these explanations can account for the existing experimental data if
either two or three neutrinos are involved in the new physics beyond the
standard electroweak model. All thses pareticle physics explanations, and
other that I have not listed, can account for the existing data from solar
neutrino experiments without conflicting with established laws of physics or
with other experimental constraints."

"The number of proposed particle physics explanations exceeds the diagnostic
power of the existing solar neutrino experiments. I think it is unlikely
that the next generation of solar neutrinos experiments will be able to
eliminate all but one possible particle physics explanation."


I'll summarize my own explanation as simply that the central temperature of
the Sun is just a bit lower than our current simulations predict -- due to
the deposition of gravitational energy into the Sun amounting to about 1% of
the measured output (which is not included in current simulations). The
'slightly lower temperature' solution was found sufficient to explain all
differences in the past -- but no suitable mechanical explanation for the
energy source (i.e. differential rotation of the Sun) could be found. The
'low' 8B (chlorine) measurements are thus explained (due to the very strong
temperature dependence of the 8B reaction) -- simultaneously with with the
minimal change in neutrinos from other chains.

greywolf42
ubi dubium ibi libertas