Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Measurement of Secondary Muon Angular Distributions   Project GRAND is an array of proportional wire chambers composed of 64
stations with each station containing eight proportional wire planes and a 50
mm steel plate. The proportional wire planes together with the steel absorber
allow a measurement of the angle and identity of single muon tracks. Of the two
data-taking triggers, one is for single tracks. Since the rate of single muon
tracks at sea level above the muon energy threshold of the experiment (0.1 GeV)
is substantial, good statistics are available by accumulating several years of
data. A map in sidereal right ascension and declination is obtained as well as
one in a sun-centered coordinate system in order to study the sidereal and
solar effects separately.

14
The categories of this paper are: math-ph
11
The categories of this paper are: hep-lat
4
The categories of this paper are: cond-mat
36
The categories of this paper are: cmp-lg
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The categories of this paper are: dg-ga
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The categories of this paper are: eess
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The categories of this paper are: nucl-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: alg-geom
22
The categories of this paper are: chao-dyn
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The categories of this paper are: q-fin
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The categories of this paper are: q-alg
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The categories of this paper are: comp-gas
1
The categories of this paper are: cs
23
The categories of this paper are: solv-int
13
The categories of this paper are: quant-ph