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- The CERN short baseline (SBL) experiments NOMAD [93]
and CHORUS [94] are appearance experiments searching
for
and, with less sensitivity, to
,
in the region of large and small
that was especially
motivated by mixed dark matter scenarios. The NOMAD limits are almost
final, and CHORUS has completed Phase I. They imply
for large .
- LSND [33] is the only oscillation experiment with a
positive appearance signal. Their final transition probability, based on
both
and
,
is
%. This is slightly lower
than their earlier results, reopening the possibility of scenarios
(Section ). KARMEN 2 [95] sees no
evidence for oscillations. However, there is a small region of parameters
(
eV,
) for which
they are consistent when analyzed the same way. The LSND, atmospheric,
and solar neutrino results imply three distinct values of , most
likely requiring
four neutrinos. Since the lineshape only allows three light active neutrinos, this
would imply the need for a light sterile neutrino mixing with the active ones.
It is therefore crucial to confirm (or not) the LSND results. The miniBoone
(or later two-detector version, Boone) at Fermilab will be sensitive to the
LSND range [33]. An additional experiment would be useful.
- The reactor long baseline experiments [81] CHOOZ and
Palo Verde exclude disappearance for
down
to
eV. They therefore excluded
as the
dominant effect in atmospheric neutrinos. (The
zenith distributions from SuperK excluded this possibility independently.)
However, could still play a subleading role.
The future Kamland experiment in Kamiokande [81]
will have a sensitivity to reactors within several hundred km.
It should be sensitive to
down to
for
eV, i.e., all of the solar LMA range. There is also a Krasnoyarsk
proposal to go down to
few
.
- Accelerator long baseline experiments are designed to search for disappearance and/or or appearance in the atmospheric neutrino range
in a cleaner laboratory environment.
The K2K (KEK to Kamiokande) experiment [42], which is already running, looks
for disappearance. It is sensitive to the upper part of the atmospheric range.
MINOS-NUMI (Fermilab-Soudan) [43] will search
for disappearance in the first phase, while the CNGS (Cern-Gran Sasso)
program (OPERA and ICARUS) [44,45,91]
will concentrate on appearance. They should cover most of the atmospheric range.
Next: More distant possibilities
Up: LOW ENERGY NEUTRINOS
Previous: Atmospheric neutrinos [,]
Paul Langacker
2001-09-27