517 research outputs found
Note about a second "evidence" for a WIMP annual modulation
This note, with its five questions, is intended to contribute to a
clarification about a claimed "evidence" by the DAMA group of an annual
modulation of the counting rate of a Dark Matter NaI(Tl) detector as due to a
neutralino (SUSY-LSP) Dark Matter candidate.Comment: LaTex, 3 pages, 2 figure
Momentum Spectroscopy of Phase Fluctuations of an Elongated Bose-Einstein Condensate
We have measured the momentum distribution of an elongated BEC (aspect ratio
of 152), for temperatures below the critical temperature. The corresponding
coherence length is significantly smaller than the condensate length in a wide
range of temperature, in quantitative agreement with theoretical predictions.
The Lorentzian shape of the momentum spectrum supports the image of a phase
fluctuating quasicondensate.Comment: Proceedings of the International Conference on Laser Spectroscopy
(ICOLS 03), Cairns, Australia, july 200
(3+1) Massive Dirac Fermions with Ultracold Atoms in Optical Lattices
We propose the experimental realization of (3+1) relativistic Dirac fermions
using ultracold atoms in a rotating optical lattice or, alternatively, in a
synthetic magnetic field. This approach has the advantage to give mass to the
Dirac fermions by coupling the ultracold atoms to a Bragg pulse. A dimensional
crossover from (3+1) to (2+1) Dirac fermions can be obtained by varying the
anisotropy of the lattice. We also discuss under which conditions the
interatomic potentials give rise to relativistically invariant interactions
among the Dirac fermions
Momentum spectroscopy of 1D phase fluctuations in Bose-Einstein condensates
We measure the axial momentum distribution of Bose-Einstein condensates with
an aspect ratio of 152 using Bragg spectroscopy. We observe the Lorentzian
momentum distribution characteristic of one-dimensional phase fluctuations. The
temperature dependence of the width of this distribution provides a
quantitative test of quasi-condensate theory. In addition, we observe a
condensate length consistent with the absence of density fluctuations, even
when phase fluctuations are large.Comment: 4 pages, 3 figures; submitted to Phys. Rev. Let
One-dimensional behavior of elongated Bose-Einstein condensates
We study the properties of elongated Bose-Einstein condensates. First, we
show that the dimensions of the condensate after expansion differs from the 3D
Thomas-Fermi regime. We also study the coherence length of such elongated
condensates.Comment: proceeding of Quantum Gases in Low Dimension, Les Houches 2003, 8
pages, 5 figure
Resonant control of spin dynamics in ultracold quantum gases by microwave dressing
We study experimentally interaction-driven spin oscillations in optical
lattices in the presence of an off-resonant microwave field. We show that the
energy shift induced by this microwave field can be used to control the spin
oscillations by tuning the system either into resonance to achieve near-unity
contrast or far away from resonance to suppress the oscillations. Finally, we
propose a scheme based on this technique to create a flat sample with either
singly- or doubly-occupied sites, starting from an inhomogeneous Mott
insulator, where singly- and doubly-occupied sites coexist.Comment: 4 pages, 5 figure
Status and preliminary results of the ANAIS experiment at Canfranc
ANAIS (Annual Modulation with NaI's) is an experiment planned to investigate
seasonal modulation effects in the signal of galactic WIMPs using up to 107 kg
of NaI(Tl) in the Canfranc Underground Laboratory (Spain). A prototype using
one single crystal (10.7 kg) is being developed before the installation of the
complete experiment; the first results presented here show an average
background level of 1.2 counts/(keV kg day) from threshold (Ethr~4 keV) up to
10 keV.Comment: 3 pages, 2 figures, talk delivered at the 7th International Workshop
on Topics in Astroparticle and Underground Physics (TAUP 2001), September
2001, Laboratori Nazionali del Gran Sasso, Italy (to appear in the Conference
Proceedings, Nucl. Phys. B (Proc. Suppl.)
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