1,418 research outputs found
Atom-molecule theory of broad Feshbach resonances
We derive the atom-molecule theory for an atomic gas near a broad Feshbach
resonance, where the energy dependence of the atom-molecule coupling becomes
crucial for understanding experimental results. We show how our many-body
theory incorporates the two-atom physics exactly. In particular, we calculate
the magnetic moment of a two-component gas of ^{6}Li atoms for a wide range of
magnetic fields near the broad Feshbach resonance at about 834 Gauss. We find
excellent agreement with the experiment of Jochim et al. [Phys. Rev. Lett. 91,
240402 (2003)].Comment: 4 pages, 2 figure
Bright soliton trains of trapped Bose-Einstein condensates
We variationally determine the dynamics of bright soliton trains composed of
harmonically trapped Bose-Einstein condensates with attractive interatomic
interactions. In particular, we obtain the interaction potential between two
solitons. We also discuss the formation of soliton trains due to the quantum
mechanical phase fluctuations of a one-dimensional condensate.Comment: 4 pages, 2 figures, submitted to PR
First Results from the HDMS experiment in the Final Setup
The Heidelberg Dark Matter Search (HDMS) is an experiment designed for the
search for WIMP dark matter. It is using a special configuration of Ge
detectors, to efficiently reduce the background in the low-energy region below
100 keV. After one year of running the HDMS detector prototype in the Gran
Sasso Underground Laboratory, the inner crystal of the detector has been
replaced with a HPGe crystal of enriched Ge. The final setup started
data taking in Gran Sasso in August 2000. The performance and the first results
of the measurement with the final setup are discussed.Comment: 8 pages, revtex, 7 figures, Home Page of Heidelberg Non-Accelerator
Particle Physics Group: http://www.mpi-hd.mpg.de/non_acc
Highly Sensitive Gamma-Spectrometers of GERDA for Material Screening: Part 2
The previous article about material screening for GERDA points out the
importance of strict material screening and selection for radioimpurities as a
key to meet the aspired background levels of the GERDA experiment. This is
directly done using low-level gamma-spectroscopy. In order to provide
sufficient selective power in the mBq/kg range and below, the employed
gamma-spectrometers themselves have to meet strict material requirements, and
make use of an elaborate shielding system. This article gives an account of the
setup of two such spectrometers. Corrado is located in a depth of 15 m w.e. at
the MPI-K in Heidelberg (Germany), GeMPI III is situated at the Gran-Sasso
underground laboratory at 3500 m w.e. (Italy). The latter one aims at detecting
sample activities of the order ~0.01 mBq/kg, which is the current
state-of-the-art level. The applied techniques to meet the respective needs are
discussed and demonstrated by experimental results.Comment: Featured in: Proceedings of the XIV International Baksan School
"Particles and Cosmology" Baksan Valley, Kabardino-Balkaria, Russia, April
16-21,2007. INR RAS, Moscow 2008. ISBN 978-5-94274-055-9, pp. 233-238; (6
pages, 4 figures
Definitive chemical evidence for the constitutive ability of Candida albicans serotype A strains to synthesize β-1,2 linked oligomannosides containing up to 14 mannose residues
AbstractWe have previously reported the presence of phosphate bound β-1,2 linked oligomannosides with unusually high degrees of polymerization (DP>7) in the mannan of Candida albicans strain VW32. To confirm this observation, we have prepared these oligomannosides from the mannan of C. albicans strain NIH A 207. Gel filtration chromatography and TLC analysis revealed DP up to 14. For both strains, NMR analysis confirmed the exclusive presence of β-1,2 linkages in the pools of oligomannosides with a DP higher than 6 which presented an average DP of 10.6 (VW32) and 10.4 (NIH A 207). These results are important to consider in relation with the ability of these C. albicans derived oligomannosides to trigger TNFα synthesis according to their DP
Observation of a temperature dependent electrical resistance minimum above the magnetic ordering temperature in GdPdSi
Results on electrical resistivity, magnetoresistance, magnetic Results on
electrical resistivity, magnetoresistance, magnetic susceptibility, heat
capacity and Gd Mossbauer measurements on a Gd-based intermetallic compound,
GdPdSi are reported. A finding of interest is that the resistivity
unexpectedly shows a well-defined minimum at about 45 K, well above the long
range magnetic ordering temperature (21 K), a feature which gets suppressed by
the application of a magnetic field. This observation in a Gd alloy presents an
interesting scenario. On the basis of our results, we propose electron
localization induced by s-f (or d-f) exchange interaction prior to long range
magnetic order as a mechanism for the electrical resistance minimum.Comment: 4 pages, 4 figure
Bright matter wave solitons in Bose-Einstein condensates
We review recent experimental and theoretical work on the creation
of bright matter wave solitons in Bose–Einstein condensates. In two recent experiments,
solitons are formed from Bose–Einstein condensates of 7Li by utilizing
a Feshbach resonance to switch from repulsive to attractive interactions.
The solitons are made to propagate in a one-dimensional potential formed by a
focused laser beam. For repulsive interactions, the wavepacket undergoes dispersivewavepacket
spreading, while for attractive interactions, localized solitons are
formed. In our experiment, a multi-soliton train containing up to ten solitons is
observed to propagate without spreading for a duration of 2 s. Adjacent solitons
are found to interact repulsively, in agreement with a calculation based on the
nonlinear Schr¨odinger equation assuming that the soliton train is formed with an
alternating phase structure. The origin of this phase structure is not entirely clear
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