Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: First measurements of the index of refraction of gases for lithium
  atomic waves   We report here the first measurements of the index of refraction of gases for
lithium waves. Using an atom interferometer, we have measured the real and
imaginary part of the index of refraction $n$ for argon, krypton and xenon, as
a function of the gas density for several velocities of the lithium beam. The
linear dependence of $(n-1)$ with the gas density is well verified. The total
collision cross-section deduced from the imaginary part is in very good
agreement with traditional measurements of this quantity. Finally, as predicted
by theory, the real and imaginary parts of $(n-1)$ and their ratio $\rho$
exhibit glory oscillations.

25
The categories of this paper are: patt-sol
15
The categories of this paper are: nucl-ex
4
The categories of this paper are: cond-mat
37
The categories of this paper are: supr-con
18
The categories of this paper are: econ
20
The categories of this paper are: acc-phys
26
The categories of this paper are: bayes-an
12
The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc
23
The categories of this paper are: solv-int
9
The categories of this paper are: nlin
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The categories of this paper are: eess
0
The categories of this paper are: hep-ph
8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg
35
The categories of this paper are: mtrl-th