Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Device for measurement of thermal emissivity at cryogenic temperatures   In the described device, the thermal emissivity or absorptivity of the sample
is measured by substitution of the radiative heat flow between two parallel
surfaces by thermal output of a heater. Fast measurements of the mutual
emissivity for the range of the temperature of the radiating surface 25 K-150 K
are possible. The absorbing surface has a temperature between 5 K and 10 K when
LHe is used as cryoliquid. The desired measurement sensitivity is 1 mK for
temperature and 0.1 {\mu}W for heat power, respectively. The diameter of the
whole device is 50 mm and so it is possible to use a commercial dewar can for
the cooling. The form of the sample is a round plate 40 mm in diameter and 1 mm
in thickness with one tested side. The emissivity and its temperature
dependency for various surface treatments can be checked immediately before
application in a cryogenic system.

14
The categories of this paper are: math-ph
34
The categories of this paper are: chem-ph
2
The categories of this paper are: math
22
The categories of this paper are: chao-dyn
8
The categories of this paper are: hep-ex
17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
32
The categories of this paper are: atom-ph
24
The categories of this paper are: dg-ga
27
The categories of this paper are: comp-gas
18
The categories of this paper are: econ
16
The categories of this paper are: stat
31
The categories of this paper are: ao-sci
13
The categories of this paper are: quant-ph
15
The categories of this paper are: nucl-ex
37
The categories of this paper are: supr-con