Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A polarisation modulation scheme for measuring vacuum magnetic
  birefringence with static fields   A novel polarisation modulation scheme for polarimeters based on Fabry-Perot
cavities is presented. The application to the proposed HERA-X experiment aiming
to measuring the magnetic birefringence of vacuum with the HERA superconducting
magnets is discussed.

11
The categories of this paper are: hep-lat
27
The categories of this paper are: comp-gas
0
The categories of this paper are: hep-ph
34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int
22
The categories of this paper are: chao-dyn
14
The categories of this paper are: math-ph
37
The categories of this paper are: supr-con
31
The categories of this paper are: ao-sci
35
The categories of this paper are: mtrl-th
7
The categories of this paper are: hep-th
15
The categories of this paper are: nucl-ex
24
The categories of this paper are: dg-ga
30
The categories of this paper are: q-alg
19
The categories of this paper are: eess
16
The categories of this paper are: stat