1,477 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
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Evolution of the flow field in decaying active regions II. Converging flows at the periphery of naked spots
Context. In a previous work, we investigated the evolution of the flow field around sunspots during sunspot decay and compared it with the flow field of supergranular cells. The decay of a sunspot proceeds as it interacts with its surroundings. This is manifested by the changes observed in the flow field surrounding the decaying spot. Aims. We now investigate in detail the evolution of the flow field in the direct periphery of the sunspots of the same sample and aim to provide a complete picture of the role of large-scale flows present in sunspot cells. Methods. We analyse the horizontal velocity profiles of sunspots obtained from observations by the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO). We follow their evolution across the solar disc from their stable phase to their decay and their final disappearance. Results.We find two different scenarios for the evolution of the flow region surrounding a spot in the final stage of its decay: (i) either the flow cell implodes and disappears under the action of the surrounding supergranules or (ii) it outlives the spot. In the later case, an inwards flow towards the remaining naked spot develops in the vicinity closest to the spot followed by an outflow further out. These findings provide observational evidence to theoretical predictions by realistic magnetohydrodynamic (MHD) sunspot and moat region simulations. Conclusions. The Evershed flow and the moat flow, both connected to the presence of fully fledged sunspots in a spot cell, vanish when penumbrae decay. Moat flows decline into supergranular flows. The final fate of a spot cell depends on its interaction with the surrounding supergranular cells. In the case of non-imploding spot cells, the remaining naked spot develops a converging inflow driven by radiative cooling and a geometrical alignment of granules in its periphery which is similar to that observed in pores
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
Die Attraktivität von Handelsmarken-Käufern : eine empirische Analyse und strategische Empfehlungen zur Vermarktung von Handelsmarken
Im internationalen Vergleich ist der Marktanteil von Handelsmarken (bzw. Eigenmarken) im deutschen Lebensmitteleinzelhandel extrem hoch. Dies wird zwar stark durch den Erfolg des Discounters Aldi beeinflusst, doch auch im übrigen Einzelhandel weisen Handelsmarken zum Teil ein beträchtliches Wachstum auf. Dieser Trend wird sich aller Erwartung nach fortsetzen. Als Motiv des Handelmarkeneinsatzes wird häufig - neben dem Preiskampf gegen Discounter - die Profilierung der eigenen Geschäftsstelle genannt, die zur Stärkung der Kundenbindung führen soll. Aber sind Handelsmarkenkäufer tatsächlich geschäftstreuer? Dies ist eine von vielen Fragen, denen in der vorliegenden Studie nachgegangen wird. In dieser Untersuchung wird der deutsche Handelsmarkenkäufer anhand marketing-relevanter Merkmale analysiert. So lässt sich ein Eindruck gewinnen, ob Handelsmarkenkäufer aufgrund ihrer spezifischen Charakteristika ein attraktives Kundensegment darstellen. Hierzu werden Verbraucher auf Grundlage von Kassenzetteldaten - ergänzt durch eine schriftliche Befragung - zunächst in drei Gruppen mit unterschiedlicher Handelsmarken-Kaufintensität eingeteilt und anschießend mit einander verglichen. Die analysierten Größen umfassen u.a. die Qualitätsbeurteilung von Handelsmarken, die Treue gegenüber Marken und Einkaufsstätten, die Bedeutung von Preis und Qualität bei der Kaufentscheidung sowie die soziodemographischen Merkmale Alter, Geschlecht, Familiengröße, Bildung und Einkommen. Im Ergebnis kann ein sehr präzises und stimmiges Bild des deutschen Handelsmarkenkäufers gezeichnet werden. Hieraus werden strategische Empfehlungen zum Umgang mit Handelsmarken abgeleitet
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
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
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