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<font color="#000099"><b><font color="#3333ff">Physics Seminar<br>
Friday, May 4, 2011<br>
11:00AM<br>
L102/104<br>
<font color="#3333ff">Cookies & Coffee at 10:45AM<br>
<font color="#990000"><br>
</font></font></font></b></font><b><font color="#ff0000"> "Nab,
a new precise study of neutron beta decay at SNS"</font><br>
<br>
<font color="#ff0000">Dinko Pocanic<br>
Univ. of Virginia</font></b><br>
<br>
<br>
Neutron beta decay, one of the most fundamental processes in nuclear
<br>
physics, provides a highly sensitive means for exploring details and
<br>
limits of our understanding of the weak interaction. Thanks to an <br>
uncommonly precise theoretical description, neutron decay is
sensitive <br>
to tiny contributions from processes not included in the standard
model <br>
of particles and interactions. However, even after eight decades of
<br>
study, experimental knowledge of neutron beta decay significantly
lags <br>
in precision behind theory. To make matters worse, there are
serious <br>
inconsistencies in the world data set. Nab, a new experimental
program <br>
at the SNS, aims to measure precisely the poorly known
electron-neutrino <br>
correlation, "a", as well as the yet unmeasured Fierz interference
term, <br>
"b", both in unpolarized neutron decay. Nab will be followed by a <br>
program of polarized neutron decay studies. After a review of the <br>
present status of the field, this talk will describe the proposed
methods <br>
of measurement, the attendant challenges, and the goal uncertainty
limits. <br>
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