Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: KATRIN background due to surface radioimpurities   The goal of the KArlsruhe TRItrium Neutrino (KATRIN) experiment is the
determination of the effective electron antineutrino mass with a sensitivity of
0.2 eV/c$^2$ at 90% C.L. This goal can only be achieved with a very low
background level in the order of 0.01 counts per second. A possible background
source is $\alpha$-decays on the inner surface of the KATRIN Main Spectrometer.
Two $\alpha$-sources, $^{223}$Ra and $^{228}$Th, were installed at the KATRIN
Main Spectrometer with the purpose of temporarily increasing the background in
order to study $\alpha$-decay induced background processes. In this paper, we
present a possible background generation mechanism and measurements performed
with these two radioactive sources. Our results show a clear correlation
between $\alpha$-activity on the inner spectrometer surface and background from
the volume of the spectrometer. Two key characteristics of the Main
Spectrometer background -the dependency on the inner electrode offset
potential, and the radial distribution - could be reproduced with this
artificially induced background. These findings indicate a high contribution of
$\alpha$-decay induced events to the residual KATRIN background.

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The categories of this paper are: nlin
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The categories of this paper are: atom-ph
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The categories of this paper are: math-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: ao-sci
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The categories of this paper are: acc-phys
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The categories of this paper are: chao-dyn
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-th
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The categories of this paper are: math
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The categories of this paper are: supr-con
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The categories of this paper are: gr-qc
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The categories of this paper are: q-alg
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The categories of this paper are: alg-geom
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The categories of this paper are: quant-ph
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The categories of this paper are: adap-org