Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Data Analysis for a Balloon Borne Compton Polarimeter   The Gamma RAy Polarimeter Experiment (GRAPE), a balloon borne Compton
polarimeter for 50-500 keV gamma rays, was successfully flown for the second
time in 2014. GRAPE consists of 24 collimated polarimeter modules. Each module
is made up of 64 rectangular scintillators elements in a grid of 8 $\times$ 8
(36 plastic scintillators surrounded by 28 CsI scintillators). GRAPE uses
photon scattered events between 2 detector elements to measure the polarization
of the measured photons. GRAPE was flown from Fort Sumner, New Mexico on the
morning of September 26$^{\text{th}}$ 2014. GRAPE was at float altitude for
14.4 hours and the Crab (primary target) was observed for 1.8 hours (initially
planned for 8 hours). Background dominates the observations at flight
altitudes, which depends on many flight and instrument parameters (altitude,
instrument pointing, temperatures, etc). A technique based on the Principle
Component Analysis (PCA) was implemented which used the varying parameters to
estimate the background for the Crab. Our instrument design allows for an
optical crosstalk (a known issue) that arises from light exiting the
scintillator element and spilling to neighboring anodes. A model was developed
to represent the crosstalk, which was incorporated in our simulations and the
instrument response. The analysis was focused on the phase-integrated data (due
to limited statistics of the shortened observation period). A power-law
spectrum with photon index of 1.70$\pm$0.24 and a normalization of
1.01$\pm$1.35 ph/keV/s/cm$^2$ was measured. A polarization fraction of
0.43$\pm$0.4 and a polarization angle of 56$^\circ \pm$30$^\circ$ was measured
for the phase integrated Crab observation in the 70-200 keV energy range. This
result was not sufficiently significant enough to further our understanding of
the emission mechanism.

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The categories of this paper are: dg-ga
30
The categories of this paper are: q-alg
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
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The categories of this paper are: solv-int
28
The categories of this paper are: alg-geom
12
The categories of this paper are: nucl-th
2
The categories of this paper are: math
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
29
The categories of this paper are: funct-an
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The categories of this paper are: acc-phys
7
The categories of this paper are: hep-th
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The categories of this paper are: bayes-an
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The categories of this paper are: stat
11
The categories of this paper are: hep-lat