Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Electron Track Reconstruction and Improved Modulation for Photoelectric
  X-ray Polarimetry   The key to photoelectric X-ray polarimetry is the determination of the
emission direction of photoelectrons. Because of the low mass of an electron,
the ionisation trajectory is not straight and the useful information needed for
polarimetry is stored mostly in the initial part of the track where less energy
is deposited. We present a new algorithm, based on the shortest path problem in
graph theory, to reconstruct the 2D electron track from the measured image that
is blurred due to transversal diffusion along drift and multiplication in the
gas chamber. Compared with previous methods based on moment analysis, this
algorithm allows us to identify the photoelectric interaction point more
accurately and precisely for complicated tracks resulting from high energy
photons or low pressure chambers. This leads to a better position resolution
and a higher degree of modulation toward high energy X-rays. The new algorithm
is justified using simulations and measurements with the gas pixel detector
(GPD), and it should also work for other polarimetric techniques such as a time
projection chamber (TPC). As the improvement is restricted in the high energy
band, this new algorithm shows limited improvement for the sensitivity of GPD
polarimeters, but it may have a larger potential for low-pressure TPC
polarimeters.

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The categories of this paper are: eess
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The categories of this paper are: q-fin
32
The categories of this paper are: atom-ph
4
The categories of this paper are: cond-mat
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The categories of this paper are: solv-int
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The categories of this paper are: patt-sol
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The categories of this paper are: funct-an
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The categories of this paper are: hep-lat
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The categories of this paper are: q-bio
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The categories of this paper are: comp-gas
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The categories of this paper are: econ
35
The categories of this paper are: mtrl-th
2
The categories of this paper are: math
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The categories of this paper are: dg-ga
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The categories of this paper are: alg-geom
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The categories of this paper are: cmp-lg