Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: To the measurement of the radius via an electron scattering   We propose an experiment for an accurate measurement of the proton radius. A
key feature of our proposal is an iron-free magnetic spectrometer. Projected
systematics uncertainties will allow a 1% level accuracy for the $r_p$ value.

20
The categories of this paper are: acc-phys
10
The categories of this paper are: q-bio
18
The categories of this paper are: econ
13
The categories of this paper are: quant-ph
28
The categories of this paper are: alg-geom
14
The categories of this paper are: math-ph
30
The categories of this paper are: q-alg
17
The categories of this paper are: q-fin
6
The categories of this paper are: astro-ph
25
The categories of this paper are: patt-sol
8
The categories of this paper are: hep-ex
27
The categories of this paper are: comp-gas
11
The categories of this paper are: hep-lat
5
The categories of this paper are: gr-qc
37
The categories of this paper are: supr-con
32
The categories of this paper are: atom-ph