Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Efficient positronium laser excitation for antihydrogen production in a
  magnetic field   Antihydrogen production by charge exchange reaction between Positronium (Ps)
atoms and antiprotons requires an efficient excitation of Ps atoms up to high-n
levels (Rydberg levels). In this study it is assumed that a Ps cloud is
produced within a relatively strong uniform magnetic field (1 Tesla) and with a
relatively high temperature (100 K). Consequently, the structure of energy
levels are deeply modified by Zeeman and motional Stark effects. A two-step
laser light excitation, the first one from ground to n=3 and the second from
this level to a Rydberg level, is proposed and the physics of the problem is
discussed. We derive a simple formula giving the absorption probability with
substantially incoherent laser pulses. A 30% population deposition in high-$n$
states can be reached with feasible lasers suitably tailored in power and
spectral bandwidth.

8
The categories of this paper are: hep-ex
14
The categories of this paper are: math-ph
1
The categories of this paper are: cs
36
The categories of this paper are: cmp-lg
23
The categories of this paper are: solv-int
37
The categories of this paper are: supr-con
17
The categories of this paper are: q-fin
34
The categories of this paper are: chem-ph
10
The categories of this paper are: q-bio
35
The categories of this paper are: mtrl-th
27
The categories of this paper are: comp-gas
32
The categories of this paper are: atom-ph
9
The categories of this paper are: nlin
2
The categories of this paper are: math
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an