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From: franklinhu on 1 Jun 2010 16:25
The detection of a tau-neutrino from a muon-neutrino beam has been
described in the article:

http://press.web.cern.ch/press/PressReleases/Releases2010/PR08.10E.html

However, I have a fundamental question about whether this detection
shows that muon neutrinos convert into tau neutrinos.

I have questioned the validity of the statement that there really are
3 types of neutrinos based on the evidence from Bookhaven in 1962
where it was determined that there were at least 2 type of neutrinos
since a muon neutrino beam produced only muons and no electrons.

But how could we really determine that there are 2 neutrino types when
only 1 type of neutrino was used in the experiment? A similar
experiment using only electron neutrinos was not performed which
leaves open the possiblity that the conditions were simply not
favorable to producing electron neutrinos and that all neutrinos are
really the same. See my google groups discussion:

http://groups.google.com/group/sci.physics/msg/372392984ac87e16

http://groups.google.com/group/sci.physics/msg/b37030e0d7b6ac8b


If all neutrinos are in fact, the same, then the observation of a tau
neutrino from a muon neutrino beam would not be unexpected and would
fail to prove that muon neutrinos oscillate to tau neutrinos. One
would first have to convincingly show that muon electrons produce only
muon neutrinos and electron neutrinos only produce electron neutrinos,
preferably with the same energy range and using the same experimental
setup which allows the neutrinos to travel only a short distance
before detection.

I wasn't able to get a reference to any such experiment from my
previous posts, but I'm sure it must be out there since science is
totally convinced that there are 3 types.

So my question is what experiments have been done that conclusively
determine the different types of neutrinos besides the 1962 Brookhaven
experiment?

-fhuneutrino
From: eric gisse on 1 Jun 2010 20:14
franklinhu wrote:

> The detection of a tau-neutrino from a muon-neutrino beam has been
> described in the article:
>
> http://press.web.cern.ch/press/PressReleases/Releases2010/PR08.10E.html
>
> However, I have a fundamental question about whether this detection
> shows that muon neutrinos convert into tau neutrinos.
>
> I have questioned the validity of the statement that there really are
> 3 types of neutrinos based on the evidence from Bookhaven in 1962
> where it was determined that there were at least 2 type of neutrinos
> since a muon neutrino beam produced only muons and no electrons.
>
> But how could we really determine that there are 2 neutrino types when
> only 1 type of neutrino was used in the experiment?

Detection of two, emission of one? The reasoning doesn't strike me as
complicated.

> A similar
> experiment using only electron neutrinos was not performed which
> leaves open the possiblity that the conditions were simply not
> favorable to producing electron neutrinos and that all neutrinos are
> really the same.

Uhhh, no. If your knowledge of the subject consists only what was done in
Brookhaven in '62, you should do yourself a favor and catch up.

> See my google groups discussion:
>
> http://groups.google.com/group/sci.physics/msg/372392984ac87e16
>
> http://groups.google.com/group/sci.physics/msg/b37030e0d7b6ac8b
>
>
> If all neutrinos are in fact, the same

They aren't. Familiarize yourself with the state of the art instead of mid
20th century knowledge.

[...]
From: Tom Roberts on 3 Jun 2010 00:21
franklinhu wrote:
> The detection of a tau-neutrino from a muon-neutrino beam has been
> described in the article:
> http://press.web.cern.ch/press/PressReleases/Releases2010/PR08.10E.html
> However, I have a fundamental question about whether this detection
> shows that muon neutrinos convert into tau neutrinos.

A single event does not show that muon neutrinos oscillate into tau neutrinos.
There is a small admixture of tau neutrinos in the beam.

The measurement of neutrino oscillation depends on rates. They measure the
composition of the beam in a near detector, and measure it again in a far
detector, and compare the two energy spectra, looking for energy-dependent
differences. The oscillation at a given distance is energy dependent.

The CNGS beam is an undifferentiated broadband hadron shower focused for one
sign with magnetic horns. When setup for muon neutrinos, there are
contaminations of other neutrino types of ~7%. There will be some tau neutrinos,
but a very small fraction because:
a) the taus are not focused by the horns (ct=87 microns, horns are meters away)
b) the taus are only produced by minor processes (not pi or K decay)

I don't know the details, but the experimenters surely do.


> I have questioned the validity of the statement that there really are
> 3 types of neutrinos based on the evidence from Bookhaven in 1962
> where it was determined that there were at least 2 type of neutrinos
> since a muon neutrino beam produced only muons and no electrons.

The tau and its neutrino were not known in 1962.


> But how could we really determine that there are 2 neutrino types when
> only 1 type of neutrino was used in the experiment?

No existing neutrino beam is free of contamination by other types of neutrinos.

A neutrino factory would provide a pure muon neutrino plus
electron antineutrino beam with contamination by other types
well below 10^-9.


> A similar
> experiment using only electron neutrinos was not performed

Yes. Pure electron neutrino beams are difficult. Reactors come close, but those
are mostly anti neutrinos at rather low energy.


> If all neutrinos are in fact, the same, then the observation of a tau
> neutrino from a muon neutrino beam would not be unexpected and would
> fail to prove that muon neutrinos oscillate to tau neutrinos

But if all neutrinos are the same it is not possible to explain the many
experimental observations of their differences.

There are confirming experiments at e+e- colliders that indicate there are 3
types of neutrinos. These are related to the Z decay width and the total
cross-section. The PDG lists two values for the number of neutrino types:
2.984 +- 0.008
2.92 +- -.05


> So my question is what experiments have been done that conclusively
> determine the different types of neutrinos besides the 1962 Brookhaven
> experiment?

A perusal of http://pdg.lbl.gov ought to provide references.


Tom Roberts
From: Old Wolf on 3 Jun 2010 03:20
I had a thought on this topic too. is it possible that
the neutrinos have no rest mass,
but by the energy-time uncertainty principle the mass value
of zero can be subject to uncertainty for a small time period,
so there is a very small amplitude for a neutrino to interact
with the Higgs field and have a 'zag' phase (which means it
also has an amplitude to oscillate).
From: franklinhu on 4 Jun 2010 14:29
On Jun 2, 9:21 pm, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote:
> franklinhu wrote:
> > The detection of a tau-neutrino from a muon-neutrino beam has been
> > described in the article:
> >http://press.web.cern.ch/press/PressReleases/Releases2010/PR08.10E.html
> > However, I have a fundamental question about whether this detection
> > shows that muon neutrinos convert into tau neutrinos.
>
> A single event does not show that muon neutrinos oscillate into tau neutrinos.
> There is a small admixture of tau neutrinos in the beam.
>
> The measurement of neutrino oscillation depends on rates. They measure the
> composition of the beam in a near detector, and measure it again in a far
> detector, and compare the two energy spectra, looking for energy-dependent
> differences. The oscillation at a given distance is energy dependent.
>
> The CNGS beam is an undifferentiated broadband hadron shower focused for one
> sign with magnetic horns. When setup for muon neutrinos, there are
> contaminations of other neutrino types of ~7%. There will be some tau neutrinos,
> but a very small fraction because:
>   a) the taus are not focused by the horns (ct=87 microns, horns are meters away)
>   b) the taus are only produced by minor processes (not pi or K decay)
>
> I don't know the details, but the experimenters surely do.
>
> > I have questioned the validity of the statement that there really are
> > 3 types of neutrinos based on the evidence from Bookhaven in 1962
> > where it was determined that there were at least 2 type of neutrinos
> > since a muon neutrino beam produced only muons and no electrons.
>
> The tau and its neutrino were not known in 1962.
>
> > But how could we really determine that there are 2 neutrino types when
> > only 1 type of neutrino was used in the experiment?
>
> No existing neutrino beam is free of contamination by other types of neutrinos.
>
>         A neutrino factory would provide a pure muon neutrino plus
>         electron antineutrino beam with contamination by other types
>         well below 10^-9.
>
> > A similar
> > experiment using only electron neutrinos was not performed
>
> Yes. Pure electron neutrino beams are difficult. Reactors come close, but those
> are mostly anti neutrinos at rather low energy.
>
> > If all neutrinos are in fact, the same, then the observation of a tau
> > neutrino from a muon neutrino beam would not be unexpected and would
> > fail to prove that muon neutrinos oscillate to tau neutrinos
>
> But if all neutrinos are the same it is not possible to explain the many
> experimental observations of their differences.
>
You know, I have been searching for such experimental obervation of
their differences and have found none. If you search, I think you
won't find any either. All we have are observations of taus, muons,
and electrons which we track down to neutrinos. I find nothing that
says electron neutrinos do something measurably different from muon
neutrinos. From the pdg, you can find lists of neutrino properties,
all of which place limits on the mass and these appear different, but
it is a limit which is still all consistent with zero or all being the
same mass. What we seem to be finding is that any neutrino can produce
any of the tau, muon, or electron neutrinos. Which either means they
can change into each other, OR, that there is only one neutrino which
can manifest istelf by producing either an electron, muon or tau.

So really, what are the observational differences?

> There are confirming experiments at e+e- colliders that indicate there are 3
> types of neutrinos. These are related to the Z decay width and the total
> cross-section. The PDG lists two values for the number of neutrino types:
>         2.984 +- 0.008
>         2.92 +- -.05

You mean this reference:
http://pdg.lbl.gov/2009/reviews/rpp2009-rev-light-neutrino-types.pdf

Well, this makes a pile of assumptions to come up with a "Limit" for
the number of neutrinos based on all of these assumptions, where there
are presumptions about the behavior of Z particles based upon the
Standard Model. "The invisible width is assumed to be due to Nν light
neutrino" doesn't sound much like the line is definitely attributed to
the neutrino species - at best, it is a guess.

So the number they come upo with is 2.92 - isn't that a little like
having 2.92 children? This is kinda denying that there can be 3
neutrinos as the experiment says there must be less than 3. In my
opinion, this throws into question the whole validity of this approach
since it approaches the question in a most indirect fashion. Neither
can it distinguish between the types of supposed neutrinos involved. I
find this kind of evidence less than convincing.

>
> > So my question is what experiments have been done that conclusively
> > determine the different types of neutrinos besides the 1962 Brookhaven
> > experiment?
>
> A perusal ofhttp://pdg.lbl.govought to provide references.

I've perused, still looking....

As far as I can see, the concept of multiple neutrinos came out of the
1962 experiment which was never replicated or questioned. (unless
someone can prove differently with a reference).

>
> Tom Roberts

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