Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Antihydrogen and mirror-trapped antiproton discrimination:
  Discriminating between antihydrogen and mirror-trapped antiprotons in a
  minimum-B trap   Recently, antihydrogen atoms were trapped at CERN in a magnetic minimum
(minimum-B) trap formed by superconducting octupole and mirror magnet coils.
The trapped antiatoms were detected by rapidly turning off these magnets,
thereby eliminating the magnetic minimum and releasing any antiatoms contained
in the trap. Once released, these antiatoms quickly hit the trap wall,
whereupon the positrons and antiprotons in the antiatoms annihilated. The
antiproton annihilations produce easily detected signals; we used these signals
to prove that we trapped antihydrogen. However, our technique could be
confounded by mirror-trapped antiprotons, which would produce
seemingly-identical annihilation signals upon hitting the trap wall. In this
paper, we discuss possible sources of mirror-trapped antiprotons and show that
antihydrogen and antiprotons can be readily distinguished, often with the aid
of applied electric fields, by analyzing the annihilation locations and times.
We further discuss the general properties of antiproton and antihydrogen
trajectories in this magnetic geometry, and reconstruct the antihydrogen energy
distribution from the measured annihilation time history.

26
The categories of this paper are: bayes-an
32
The categories of this paper are: atom-ph
28
The categories of this paper are: alg-geom
23
The categories of this paper are: solv-int
17
The categories of this paper are: q-fin
0
The categories of this paper are: hep-ph
33
The categories of this paper are: plasm-ph
27
The categories of this paper are: comp-gas
6
The categories of this paper are: astro-ph
1
The categories of this paper are: cs
10
The categories of this paper are: q-bio
29
The categories of this paper are: funct-an
19
The categories of this paper are: eess
14
The categories of this paper are: math-ph
24
The categories of this paper are: dg-ga
18
The categories of this paper are: econ