Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Identifying the nature of high energy Astroparticles   High energy Astroparticles include Cosmic Ray, gamma ray and neutrinos, all
of them coming from the universe. The origin and production, acceleration and
propagation mechanisms of ultrahigh-energy CR (up to $10^{20}$ eV) are still
unknown. Knowledge on particle interactions taking place at those energies,
useful for studying current theories on particle physics, can be obtained only
from measurements of high energy astroparticles. In the present document some
techniques on data analysis of mass composition of UHECR with the Pierre Auger
Observatory are described. The relevance of the muon component of air showers
produced by the primary CR, as well as some low energy simulations of that
component, are explained.

15
The categories of this paper are: nucl-ex
31
The categories of this paper are: ao-sci
30
The categories of this paper are: q-alg
5
The categories of this paper are: gr-qc
12
The categories of this paper are: nucl-th
35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn
4
The categories of this paper are: cond-mat
32
The categories of this paper are: atom-ph
1
The categories of this paper are: cs
7
The categories of this paper are: hep-th
16
The categories of this paper are: stat
28
The categories of this paper are: alg-geom
9
The categories of this paper are: nlin
11
The categories of this paper are: hep-lat
36
The categories of this paper are: cmp-lg