Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nuclear structure study of 19,20,21N nuclei by gamma spectroscopy   The structure of neutron rich nitrogen nuclei has been studied by use of
neutron removal reaction and inelastic scattering. Mass and charge deformations
have been deduced for the first excited state of 21N, which indicates the
partial persitence of the N=14 subshell closure in nitrogen isotopes. The
spectroscopic information obtained on the structure of 19,20,21N confirms the
results from a previous experiment.

35
The categories of this paper are: mtrl-th
27
The categories of this paper are: comp-gas
1
The categories of this paper are: cs
11
The categories of this paper are: hep-lat
2
The categories of this paper are: math
28
The categories of this paper are: alg-geom
26
The categories of this paper are: bayes-an
31
The categories of this paper are: ao-sci
16
The categories of this paper are: stat
8
The categories of this paper are: hep-ex
18
The categories of this paper are: econ
37
The categories of this paper are: supr-con
5
The categories of this paper are: gr-qc
21
The categories of this paper are: adap-org
6
The categories of this paper are: astro-ph
20
The categories of this paper are: acc-phys