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Title: Storage ring to investigate cold unidimensional atomic collisions

Abstract

In this paper we employ a circulating ring of trapped atoms, that we have named the atomotron, to study cold collisions. The atomotron is obtained from a conventional magneto-optical trap when the two pairs of normally retroreflecting Gaussian laser beams in the x-y plane are slightly offset. Circulating stable atomic orbits then form a racetrack geometry in this plane. The circulating atom flux behaves similarly to an atomic beam with an average tangential velocity much greater than the transverse components, and is therefore suitable for one-dimensional atomic collision studies. Using the atomotron, we have investigated the polarization dependence of ultracold photoassociation collisions between Rb atoms circulating in the racetrack. The ability to investigate collisions in ultracold circulating atomic rings reveals alignment and orientation properties that are averaged away in ordinary three-dimensional magneto-optical trap collision processes.

Authors:
; ; ; ; ;  [1]
  1. Instituto de Fisica de SaoCarlos, Universidade de SaoPaulo, Caixa Postal 369, 13560-970, SaoCarlos-SP (Brazil)
Publication Date:
OSTI Identifier:
20786240
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. A; Journal Volume: 72; Journal Issue: 6; Other Information: DOI: 10.1103/PhysRevA.72.060701; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; ATOM-ATOM COLLISIONS; ATOMIC BEAMS; ATOMS; COOLING; GEOMETRY; LASER RADIATION; MAGNETO-OPTICAL EFFECTS; ORBITS; ORIENTATION; PHOTON-ATOM COLLISIONS; POLARIZATION; RADIATION PRESSURE; RUBIDIUM; STORAGE RINGS; TRAPPING; TRAPS

Citation Formats

Marcassa, L. G., Caires, A. R. L., Nascimento, V. A., Dulieu, O., Weiner, J., and Bagnato, V. S. Storage ring to investigate cold unidimensional atomic collisions. United States: N. p., 2005. Web. doi:10.1103/PHYSREVA.72.0.
Marcassa, L. G., Caires, A. R. L., Nascimento, V. A., Dulieu, O., Weiner, J., & Bagnato, V. S. Storage ring to investigate cold unidimensional atomic collisions. United States. doi:10.1103/PHYSREVA.72.0.
Marcassa, L. G., Caires, A. R. L., Nascimento, V. A., Dulieu, O., Weiner, J., and Bagnato, V. S. Thu . "Storage ring to investigate cold unidimensional atomic collisions". United States. doi:10.1103/PHYSREVA.72.0.
@article{osti_20786240,
title = {Storage ring to investigate cold unidimensional atomic collisions},
author = {Marcassa, L. G. and Caires, A. R. L. and Nascimento, V. A. and Dulieu, O. and Weiner, J. and Bagnato, V. S.},
abstractNote = {In this paper we employ a circulating ring of trapped atoms, that we have named the atomotron, to study cold collisions. The atomotron is obtained from a conventional magneto-optical trap when the two pairs of normally retroreflecting Gaussian laser beams in the x-y plane are slightly offset. Circulating stable atomic orbits then form a racetrack geometry in this plane. The circulating atom flux behaves similarly to an atomic beam with an average tangential velocity much greater than the transverse components, and is therefore suitable for one-dimensional atomic collision studies. Using the atomotron, we have investigated the polarization dependence of ultracold photoassociation collisions between Rb atoms circulating in the racetrack. The ability to investigate collisions in ultracold circulating atomic rings reveals alignment and orientation properties that are averaged away in ordinary three-dimensional magneto-optical trap collision processes.},
doi = {10.1103/PHYSREVA.72.0},
journal = {Physical Review. A},
number = 6,
volume = 72,
place = {United States},
year = {Thu Dec 15 00:00:00 EST 2005},
month = {Thu Dec 15 00:00:00 EST 2005}
}
  • The dissociative recombination cross section between HD[sup +] molecules and electrons at energies between 0.3 and 40 eV has been measured for the first time in an ion storage ring. The ion beam, stored with a mean lifetime of [similar to]5 s, was observed to be vibrationally cold. In the measured cross section, theoretically predicted high-energy resonances appeared, which can be attributed to recombination via doubly excited Rydberg states of HD.
  • Envelope instability is investigated in a storage ring using particle simulation. A typical distortion pattern of the instability is observed in transverse phase planes of cold ion beams considering the storage ring both with and without ring periodicity perturbations. The dependence of the blow-up rate of the instability on the single particle phase advance of the storage ring is calculated. Typical {ital e}-folding blow-up times of the envelope instability increase from 10{sup {minus}5}s to 10{sup {minus}2}s when the single particle phase advance is smaller than 90{degree}. {copyright} {ital 1996 American Institute of Physics.}
  • Using the ORBIT code we study the sensitivity of electron cloud properties with respect to different proton beam profiles, the secondary electron yield (SEY) parameter, and the proton loss rate. Our model uses a cold proton bunch to generate primary electrons and electromagnetic field for electron cloud dynamics. We study the dependence of the prompt and swept electron signals vs the bunch charge and the recovery of electron clouds after sweeping on the beam loss rate and the SEY. The simulation results are compared with the experimental data measured at the proton storage ring at the Los Alamos National Laboratory.more » Our simulations indicate that the fractional proton loss rate in the field-free straight section may be an exponential function of proton beam charge and may also be lower than the averaged fractional proton loss rate over the whole ring.« less
  • The cross section for neutral-channel dissociative recombination of vibrationally cooled H[sub 3][sup +] at energies between 0.0025 and 30 eV has been measured by utilizing the electron cooler at the storage ring CRYRING. The molecular ions were stored at an energy of 32.6 MeV and phase-space cooled by the electron cooler for about 8 s prior to data taking. A peak in the cross section at 9.4 eV is interpreted as a direct adiabatic neutral-channel recombination through the [sup 2][ital A][sub 1] resonant state. The cross section below 1 eV is in rather good agreement with single-pass data.
  • Three-dimensional (3D) ordering of a charged-particle beams circulating in a storage ring is systematically studied with a molecular-dynamics simulation code. An ion beam can exhibit a 3D ordered configuration at ultralow temperature as a result of powerful 3D laser cooling. Various unique characteristics of the ordered beams, different from those of crystalline beams, are revealed in detail, such as the single-particle motion in the transverse and longitudinal directions, and the dependence of the tune depression and the Coulomb coupling constant on the operating points.