Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Measurement of the angular correlation between the two gamma rays
  emitted in the radioactive decays of a $^{60}$Co source with two NaI(Tl)
  scintillator   We implemented a didactic experiment to study the angular correlation between
the two gamma rays emitted in typical $^{60}$Co radioactive decays. We used two
NaI(Tl) scintillators, already available in our laboratory, and a low-activity
$^{60}$Co source. The detectors were mounted on two rails, with the source at
their center. The first rail was fixed, while the second could be rotated
around the source. We performed several measurements by changing the angle
between the two scintillators in the range from $90^\circ$ to $180^\circ$.
Dedicated background runs were also performed, removing the source from the
experimental setup. We found that the signal rate increases with the angular
separation between the two scintillators, with small discrepancies from the
theoretical expectations.

9
The categories of this paper are: nlin
8
The categories of this paper are: hep-ex
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
21
The categories of this paper are: adap-org
4
The categories of this paper are: cond-mat
18
The categories of this paper are: econ
31
The categories of this paper are: ao-sci
36
The categories of this paper are: cmp-lg
27
The categories of this paper are: comp-gas
0
The categories of this paper are: hep-ph
1
The categories of this paper are: cs
29
The categories of this paper are: funct-an
37
The categories of this paper are: supr-con
25
The categories of this paper are: patt-sol
6
The categories of this paper are: astro-ph