176 research outputs found
Diagnostic criterion for crystallized beams
Small ion crystals in a Paul trap are stable even in the absence of laser
cooling. Based on this theoretically and experimentally well-established fact
we propose the following diagnostic criterion for establishing the presence of
a crystallized beam: Absence of heating following the shut-down of all cooling
devices. The validity of the criterion is checked with the help of detailed
numerical simulations.Comment: REVTeX, 11 pages, 4 figures; submitted to PR
ELENA: An Upgrade to the Antiproton Decelerator
A small decelerator ring with electron cooling is proposed to produce dense antiproton beams at very low energies. The ring should be installed between the existing AD and the experimental area
Production of antihydrogen at reduced magnetic field for anti-atom trapping
We have demonstrated production of antihydrogen in a 1T solenoidal
magnetic field. This field strength is significantly smaller than that used in
the first generation experiments ATHENA (3T) and ATRAP (5T). The
motivation for using a smaller magnetic field is to facilitate trapping of
antihydrogen atoms in a neutral atom trap surrounding the production region. We
report the results of measurements with the ALPHA (Antihydrogen Laser PHysics
Apparatus) device, which can capture and cool antiprotons at 3T, and then
mix the antiprotons with positrons at 1T. We infer antihydrogen production
from the time structure of antiproton annihilations during mixing, using mixing
with heated positrons as the null experiment, as demonstrated in ATHENA.
Implications for antihydrogen trapping are discussed
Centrifugal separation and equilibration dynamics in an electron-antiproton plasma
Charges in cold, multiple-species, non-neutral plasmas separate radially by
mass, forming centrifugally-separated states. Here, we report the first
detailed measurements of such states in an electron-antiproton plasma, and the
first observations of the separation dynamics in any centrifugally-separated
system. While the observed equilibrium states are expected and in agreement
with theory, the equilibration time is approximately constant over a wide range
of parameters, a surprising and as yet unexplained result. Electron-antiproton
plasmas play a crucial role in antihydrogen trapping experiments
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.Comment: 17 figure
Compression of Antiproton Clouds for Antihydrogen Trapping
Control of the radial profile of trapped antiproton clouds is critical to
trapping antihydrogen. We report the first detailed measurements of the radial
manipulation of antiproton clouds, including areal density compressions by
factors as large as ten, by manipulating spatially overlapped electron plasmas.
We show detailed measurements of the near-axis antiproton radial profile and
its relation to that of the electron plasma
A novel antiproton radial diagnostic based on octupole induced ballistic loss
We report results from a novel diagnostic that probes the outer radial
profile of trapped antiproton clouds. The diagnostic allows us to determine the
profile by monitoring the time-history of antiproton losses that occur as an
octupole field in the antiproton confinement region is increased. We show
several examples of how this diagnostic helps us to understand the radial
dynamics of antiprotons in normal and nested Penning-Malmberg traps. Better
understanding of these dynamics may aid current attempts to trap antihydrogen
atoms
Alpha Antihydrogen Experiment
ALPHA is an experiment at CERN, whose ultimate goal is to perform a precise
test of CPT symmetry with trapped antihydrogen atoms. After reviewing the
motivations, we discuss our recent progress toward the initial goal of stable
trapping of antihydrogen, with some emphasis on particle detection techniques.Comment: Invited talk presented at the Fifth Meeting on CPT and Lorentz
Symmetry, Bloomington, Indiana, June 28-July 2, 201
Three Dimensional Annihilation Imaging of Antiprotons in a Penning Trap
We demonstrate three-dimensional annihilation imaging of antiprotons trapped
in a Penning trap. Exploiting unusual feature of antiparticles, we investigate
a previously unexplored regime in particle transport; the proximity of the trap
wall. Particle loss on the wall, the final step of radial transport, is
observed to be highly non-uniform, both radially and azimuthally. These
observations have considerable implications for the production and detection of
antihydrogen atoms.Comment: Invited Talk at NNP03, Workshop on Non-Neutral Plasmas, 200
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