Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Probing the helium dimer by relativistic highly-charged projectiles   We study the fragmentation of He$_2$ dimers into He$^+$ ions by relativistic
highly-charged projectiles. It is demonstrated that the interaction between an
ultrafast projectile with an extremely extended object -- the helium dimer --
possesses interesting features which are absent in collisions with "normal"
molecules. It is also shown that such projectiles, due to their enormous
interaction range, can accurately probe the ground state of the dimer and even
be used for a precise determination of its binding energy.

18
The categories of this paper are: econ
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio
20
The categories of this paper are: acc-phys
15
The categories of this paper are: nucl-ex
30
The categories of this paper are: q-alg
4
The categories of this paper are: cond-mat
19
The categories of this paper are: eess
16
The categories of this paper are: stat
17
The categories of this paper are: q-fin
0
The categories of this paper are: hep-ph
37
The categories of this paper are: supr-con
34
The categories of this paper are: chem-ph
24
The categories of this paper are: dg-ga
32
The categories of this paper are: atom-ph
5
The categories of this paper are: gr-qc