Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Direct time domain sampling of sub-THz coherent acoustic phonon spectra
  in SrTiO$_3$ using ultrafast X-ray diffraction
2
The categories of this paper are: math
25
The categories of this paper are: patt-sol
36
The categories of this paper are: cmp-lg
32
The categories of this paper are: atom-ph
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
10
The categories of this paper are: q-bio
5
The categories of this paper are: gr-qc
13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
6
The categories of this paper are: astro-ph
33
The categories of this paper are: plasm-ph
15
The categories of this paper are: nucl-ex
21
The categories of this paper are: adap-org
34
The categories of this paper are: chem-ph
29
The categories of this paper are: funct-an