Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Stroboscopic Laser Diagnostics for Detection of Ordering in
  One-Dimensional Ion beam   A novel diagnostic method for detecting ordering in one-dimensional ion beams
is presented. The ions are excited by a pulsed laser at two different positions
along the beam and fluorescence is observed by a group of four
photomultipliers. Correlation in fluorescence signals is firm indication that
the ion beam has an ordered structure.

18
The categories of this paper are: econ
16
The categories of this paper are: stat
14
The categories of this paper are: math-ph
27
The categories of this paper are: comp-gas
37
The categories of this paper are: supr-con
4
The categories of this paper are: cond-mat
19
The categories of this paper are: eess
32
The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
1
The categories of this paper are: cs
13
The categories of this paper are: quant-ph
24
The categories of this paper are: dg-ga
6
The categories of this paper are: astro-ph
12
The categories of this paper are: nucl-th
9
The categories of this paper are: nlin
15
The categories of this paper are: nucl-ex