Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ultra-high energy cosmic ray sources and large scale magnetic fields   Protons of energies up to 10**20 eV can be subject to significant deflection
and energy dependent time delay in lage scale extragalactic or halo magnetic
fields of strengths comparable to current upper limits. By performing
3-dimensional Monte Carlo simulations of nucleon propagation, we show how
observations of arrival direction and time distributions can be used to measure
the structure and strength of large-scale magnetic fields, and constrain the
nature of the source of ultra-high energy cosmic rays.

33
The categories of this paper are: plasm-ph
22
The categories of this paper are: chao-dyn
15
The categories of this paper are: nucl-ex
26
The categories of this paper are: bayes-an
23
The categories of this paper are: solv-int
16
The categories of this paper are: stat
29
The categories of this paper are: funct-an
5
The categories of this paper are: gr-qc
30
The categories of this paper are: q-alg
13
The categories of this paper are: quant-ph
19
The categories of this paper are: eess
1
The categories of this paper are: cs
8
The categories of this paper are: hep-ex
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
37
The categories of this paper are: supr-con