Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Near-resonance Light Scattering from a High-density, Ultracold Atomic
  $^{87}$Rb Gas   We report a combined experimental and theoretical investigation of near
resonance light scattering from a high-density and ultracold atomic $^{87}$Rb
gas. The atomic sample, having a peak density $\sim 5\cdot10^{13}$
atoms/cm$^{3}$, temperature $\sim$ 65 $\mu$K and initially prepared in the F =
1 lower energy $^{87}$Rb hyperfine component, is optically pumped to the higher
energy F = 2 hyperfine level. Measurements are made of the transient hyperfine
pumping process and of the time evolution of scattering of near resonance probe
radiation on the $F = 2 \rightarrow F' = 3$ transition. Features of the
density, detuning, and temporal dependence of the signals are attributed to the
high density and consequent large optical depth of the samples.

16
The categories of this paper are: stat
35
The categories of this paper are: mtrl-th
37
The categories of this paper are: supr-con
20
The categories of this paper are: acc-phys
15
The categories of this paper are: nucl-ex
6
The categories of this paper are: astro-ph
5
The categories of this paper are: gr-qc
33
The categories of this paper are: plasm-ph
11
The categories of this paper are: hep-lat
12
The categories of this paper are: nucl-th
2
The categories of this paper are: math
36
The categories of this paper are: cmp-lg
21
The categories of this paper are: adap-org
17
The categories of this paper are: q-fin
22
The categories of this paper are: chao-dyn
7
The categories of this paper are: hep-th