Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Thermal diagnostic of the Optical Window on board LISA Pathfinder   Vacuum conditions inside the LTP Gravitational Reference Sensor must comply
with rather demanding requirements. The Optical Window (OW) is an interface
which seals the vacuum enclosure and, at the same time, lets the laser beam go
through for interferometric Metrology with the test masses. The OW is a
plane-parallel plate clamped in a Titanium flange, and is considerably
sensitive to thermal and stress fluctuations. It is critical for the required
precision measurements, hence its temperature will be carefully monitored in
flight. This paper reports on the results of a series of OW characterisation
laboratory runs, intended to study its response to selected thermal signals, as
well as their fit to numerical models, and the meaning of the latter. We find
that a single pole ARMA transfer function provides a consistent approximation
to the OW response to thermal excitations, and derive a relationship with the
physical processes taking place in the OW. We also show how system noise
reduction can be accomplished by means of that transfer function.

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The categories of this paper are: q-bio
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The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
27
The categories of this paper are: comp-gas
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The categories of this paper are: solv-int
32
The categories of this paper are: atom-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: hep-ex
28
The categories of this paper are: alg-geom
30
The categories of this paper are: q-alg
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The categories of this paper are: nucl-ex
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The categories of this paper are: funct-an
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The categories of this paper are: econ
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The categories of this paper are: dg-ga
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The categories of this paper are: stat
33
The categories of this paper are: plasm-ph