Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Positron Channeling   The possibility of channeling the low-energy relativistic positrons around
separate crystallographic axes with coaxial symmetry of negative ions in some
types of crystals is shown. The process of annihilation of positrons with
electrons of medium was studied in detail.

32
The categories of this paper are: atom-ph
5
The categories of this paper are: gr-qc
27
The categories of this paper are: comp-gas
0
The categories of this paper are: hep-ph
17
The categories of this paper are: q-fin
24
The categories of this paper are: dg-ga
37
The categories of this paper are: supr-con
25
The categories of this paper are: patt-sol
7
The categories of this paper are: hep-th
1
The categories of this paper are: cs
11
The categories of this paper are: hep-lat
16
The categories of this paper are: stat
6
The categories of this paper are: astro-ph
4
The categories of this paper are: cond-mat
35
The categories of this paper are: mtrl-th
14
The categories of this paper are: math-ph