Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Lifetime and hyperfine splitting measurements on the 7s and 6p levels in
  rubidium   We present lifetime measurements of the 7S1/2 level and the 6p manifold of
rubidium. We use a timecorrelated single-photon counting technique on a sample
of 85Rb atoms confined and cooled in a magneto-optic trap. The upper state of
the 5P1/2 repumping transition serves as the resonant intermediate level for
twophoton excitation of the 7s level. A probe laser provides the second step of
the excitation, and we detect the decay of atomic fluorescence to the 5P3/2
level at 741 nm. The decay process feeds the 6p manifold that decays to the 5s
ground state emitting UV photons. We measure lifetimes of 88.07 +- 0.40 and
120.7 +- 1.2 ns for the 7S1/2 level and 6p manifold, respectively; the
hyperfine splitting of the 7S1/2 level is 282.6 +- 1.6 MHz. The agreement with
theoretical calculations confirms the understanding of the wave functions
involved and provides confidence on the possibility of extracting weak
interaction constants from a parity nonconservation measurement.

35
The categories of this paper are: mtrl-th
2
The categories of this paper are: math
25
The categories of this paper are: patt-sol
6
The categories of this paper are: astro-ph
29
The categories of this paper are: funct-an
18
The categories of this paper are: econ
15
The categories of this paper are: nucl-ex
10
The categories of this paper are: q-bio
37
The categories of this paper are: supr-con
12
The categories of this paper are: nucl-th
34
The categories of this paper are: chem-ph
9
The categories of this paper are: nlin
21
The categories of this paper are: adap-org
13
The categories of this paper are: quant-ph
0
The categories of this paper are: hep-ph
8
The categories of this paper are: hep-ex