Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Reionization and Structure Formation with ARCADE   Structure formation in the early universe is expected to produce a
cosmological background of free-free emission. The Absolute Radiometer for
Cosmology, Astrophysics, and Diffuse Emission (ARCADE) will measure the
spectrum of the cosmic microwave background at centimeter wavelengths to detect
this signature of structure formation. I describe the ARCADE instrument and the
cryogenic engineering required to achieve mK accuracy at such long wavelengths.

13
The categories of this paper are: quant-ph
17
The categories of this paper are: q-fin
2
The categories of this paper are: math
26
The categories of this paper are: bayes-an
1
The categories of this paper are: cs
19
The categories of this paper are: eess
27
The categories of this paper are: comp-gas
4
The categories of this paper are: cond-mat
16
The categories of this paper are: stat
15
The categories of this paper are: nucl-ex
0
The categories of this paper are: hep-ph
5
The categories of this paper are: gr-qc
7
The categories of this paper are: hep-th
36
The categories of this paper are: cmp-lg
3
The categories of this paper are: physics
30
The categories of this paper are: q-alg