Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Precision measurement of the nuclear polarization in laser-cooled,
  optically pumped $^{37}\mathrm{K}$   We report a measurement of the nuclear polarization of laser-cooled,
optically-pumped $^{37}\mathrm{K}$ atoms which will allow us to precisely
measure angular correlation parameters in the beta-decay of the same atoms.
These results will be used to test the $V-A$ framework of the weak interaction
at high precision. At the TRIUMF Neutral Atom Trap (TRINAT), a magneto-optical
trap (MOT) confines and cools neutral $^{37}\mathrm{K}$ atoms and optical
pumping spin-polarizes them. We monitor the nuclear polarization of the same
atoms that are decaying in situ by photoionizing a small fraction of the
partially polarized atoms and then use the standard optical Bloch equations to
model their population distribution. We obtain an average nuclear polarization
of $P = 0.9913\pm0.0008$, which is significantly more precise than previous
measurements with this technique. Since our current measurement of the
beta-asymmetry has $0.2\%$ statistical uncertainty, the polarization
measurement reported here will not limit its overall uncertainty. This result
also demonstrates the capability to measure the polarization to $<0.1\%$,
allowing for a measurement of angular correlation parameters to this level of
precision, which would be competitive in searches for new physics.

11
The categories of this paper are: hep-lat
36
The categories of this paper are: cmp-lg
37
The categories of this paper are: supr-con
32
The categories of this paper are: atom-ph
6
The categories of this paper are: astro-ph
27
The categories of this paper are: comp-gas
25
The categories of this paper are: patt-sol
14
The categories of this paper are: math-ph
4
The categories of this paper are: cond-mat
18
The categories of this paper are: econ
12
The categories of this paper are: nucl-th
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The categories of this paper are: nlin
10
The categories of this paper are: q-bio
24
The categories of this paper are: dg-ga
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom