From: Mike Shaevitz (shaevitz@nevis.columbia.edu)
Date: Mon Apr 24 2006 - 13:32:14 CDT
Dear All,
Here is an outline of a possible letter to Orbach (or Staffin)
Mike
Letter to Orbach (or Staffin)
- A precision measurement of sin2(2th13) below the 0.01 is
recognized as not only a key next step for understanding
neutrino masses and mixing but also a key component in the
long term neutrino program. For this to be the case, the
reactor measurement must reach this precision level; a
measurement at 3 to 4 times less precision will not be very
useful in the long term.
- We believe that the Braidwood experiment is the only
currently proposed experiment that can reach this level of
precision both due to the unique features of the Braidwood
site and of the experimental design. The flat, equal
overburden for the near and far detectors coupled with
careful attention to cross checks and redundant measurements
make the Braidwood experiment unique in the ability to make
precise measurements. In addition, extensive studies of
background sources have led to a shield/tagger (veto) design
that can be used both to measure and reduce the background.
- In contrast, the Daya Bay experiment will have reduced
precision due to the layout of the site with multiple
reactors at multiple distances, large changes in near/far
overburden shielding, and a detector/veto design that is not
adequate for the precision.
- At this time, there is general consensus in the community
that the Braidwood experiment has a better design and
prospective precison than Daya Bay. To quantify this
comparison since you may view us as biased, a technical
review of the two experiments is needed.
- In summary, we strongly feel that the Braidwood experiment
is the only proposed reactor measurement of theta13 that is
at the required precision. Support for an inferior
experiment which will likely have inadequate precision is
not a wise choice for furthering our knowledge of neutrino
oscillations. We therefore suggest that R&D funding be
given to both Braidwood and Daya Bay leading to a full
technical review and choice between the experiments in 3-4
months.
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