Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Energy Spectrum of Cosmic Rays Above $3 \times 10^{17}$ eV as
  measured with the Haverah Park Array   Air showers recorded by the Haverah Park Array during the years 1974 - 1987
have been re-analysed. For the original estimate of the energy spectrum, a
relationship between the ground parameter $\rho$(600) and the primary energy,
as determined by Hillas in the 1970s, was used. Here we describe the energy
spectrum obtained using the QGSJET98 interaction model in the CORSIKA Monte
Carlo code, together with GEANT to simulate the detailed detector response to
ground particles. A new energy spectrum in the range 3 $\times$ 10$^{17}$ eV to
4 $\times$ 10$^{18}$ eV is presented.

16
The categories of this paper are: stat
24
The categories of this paper are: dg-ga
35
The categories of this paper are: mtrl-th
15
The categories of this paper are: nucl-ex
22
The categories of this paper are: chao-dyn
11
The categories of this paper are: hep-lat
27
The categories of this paper are: comp-gas
30
The categories of this paper are: q-alg
2
The categories of this paper are: math
29
The categories of this paper are: funct-an
13
The categories of this paper are: quant-ph
12
The categories of this paper are: nucl-th
1
The categories of this paper are: cs
18
The categories of this paper are: econ
26
The categories of this paper are: bayes-an
31
The categories of this paper are: ao-sci