Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A pair spectrometer for measuring multipolarities of energetic nuclear
  transitions   A multi-detector array has been designed and constructed for the simultaneous
measurement of energy- and angular correlations of electron-positron pairs.
Experimental results are obtained over a wide angular range for high-energy
transitions in 16O, 12C and 8Be. A comparison with GEANT simulations
demonstrates that angular correlations between 50 and 180 degrees of the
electron-positron pairs in the energy range between 6 and 18 MeV can be
determined with sufficient resolution and efficiency.

5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
1
The categories of this paper are: cs
10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph
16
The categories of this paper are: stat
13
The categories of this paper are: quant-ph
29
The categories of this paper are: funct-an
6
The categories of this paper are: astro-ph
11
The categories of this paper are: hep-lat
9
The categories of this paper are: nlin
36
The categories of this paper are: cmp-lg