aktualisiertes pdf - DPG-Tagungen
aktualisiertes pdf - DPG-Tagungen
aktualisiertes pdf - DPG-Tagungen
Sie wollen auch ein ePaper? Erhöhen Sie die Reichweite Ihrer Titel.
YUMPU macht aus Druck-PDFs automatisch weboptimierte ePaper, die Google liebt.
detektor mit 80mm Durchmesser ab. Dieser Detektor, der für niedere<br />
Elektronenenergien entwickelt wurde/1/, ist mit einer multihitfähigen<br />
2d ortsempfindlichen Anode versehen, die die Elektronenlawinen hinter<br />
dem Channelplate-stack nachweist. Für hochenenergetische Elektronen<br />
nimmt die Nachweiseffizienz der Channelplates jedoch stark ab. Wir haben<br />
den nutzbaren Einsatzbereich des Detektors durch eine geeignet angepasste<br />
Channelplatekonfiguration erhöht und werden erste Ergebnisse<br />
vorstellen. 1 O. Jagutzki et al. NIM A477(2002)244-249<br />
A 15.22 Do 14:00 Schellingstr. 3<br />
A high-resolution detector for charge transfer experiments involving<br />
ultracold atoms — •Wenzel Salzmann, Helmut Rathgen,<br />
Roland Wester, and Matthias Weidemüller — Physikalisches<br />
Institut, Universität Freiburg, 79104 Freiburg<br />
We are setting up a new experiment to study ion-atom collisions using<br />
lasercooled atoms as an ultracold target. Projectile ions with energies of<br />
eV - keV pass through a magneto-optical trap where rubidium atoms are<br />
stored at temperatures below 100µK[1]. Target atoms which are ionised<br />
in the collision are momentum-analysed using Recoil-Ion-Momentum-<br />
Spectroscopy (RIMS)[2]. The low target temperatures correspond to very<br />
low momentum spreads of the rubidium atoms (δp < 0.01) which ensures<br />
a high resolution measurement of the recoil ion momentum components.<br />
We use this setup to examine several aspects of charge transfer reactions,<br />
in particular dissociative charge transfer to diatomic molecular ions at<br />
eV-keV energies. By using a defined projectile beam one can extract<br />
detailed information from the recoiled ion about the internal electronic<br />
state of the neutral molecule after the collision. The dissociated states<br />
are analysed by detecting the neutral fragments and their kinetic energy.<br />
In order to prepare the ions in a defined state they are stored in a linear<br />
electrostatic ion trap at keV energies or in a Rf-trap at eV energies. The<br />
status of the experiment is presented.<br />
[1] M.v.d. Poel et al., Phys. Rev. Lett. 87, 12, 3202(2001).<br />
[2] J.Ullrich et al., J. Phys. B,30, (1997), 2917-2974.<br />
A 15.23 Do 14:00 Schellingstr. 3<br />
Fabrication of Atom Chips and their electrical properties —<br />
•Sönke Groth 1,2 , Peter Krüger 1 , Stephan Wildermuth 1 , Diana<br />
Mahalu 2 , Israel Bar-Joseph 2 , and Jörg Schmeidmayer 1 —<br />
1 Physikalisches Institut, Heidelberg, Germany — 2 Weizmann Institute of<br />
Science, Rehovot, Israel<br />
Atom Chips are used to trap neutral atoms and cool them by laser<br />
and evaporative cooling even to BEC. The advantages of atom chips are<br />
smooth surfaces for non scattered laser reflection, high current densities<br />
up to 10 7 A/cm 2 , micro shaped wires for exactly defined potentials, wire<br />
thickness from nm to µm scale and serial production.<br />
A high quality preparation process based on nanofabrication lithography<br />
capable of structures ∼ 1 µm is shown, which achieves the mentioned<br />
criteria. Electrical properties of these atom chips are investigated<br />
for measurements of wires with different aspect ratios on several substrates.<br />
The heat conductivity of the substrate is of importance for the<br />
lifetime of the wire. The technology aspects for miniaturised quantum<br />
manipulation atom optics are discussed.<br />
A 15.24 Do 14:00 Schellingstr. 3<br />
Trapping of heavy alkaline earth elements — •Umakanth<br />
Dammalapati, Gerald Ebberink, Klaus Jungmann, and Lorenz<br />
Willmann — Kernfysisch Versneller Instituut, Zernikelaan 25, 9747<br />
AA Groningen, The Netherlands<br />
We are working toward a search for a permanent electric dipole moment<br />
(edm) of a fundamental particle. An edm, which violates time reversal<br />
symmetry (T) as well as the combination of charge conjugation symmetry<br />
(C) and parity (P), is an unambiguous signal for physics beyond the standard<br />
model. Some short lived radioactive elements and the techniques for<br />
trapping and cooling of atoms offer new possibilities for edm searches. At<br />
the KVI a facility for producing short lived radioactive isotopes (TRIµP)<br />
is being set up. Here, the heavy alkaline earth element radium will be<br />
produced. Radium promises to have a high sensitivity for edm searches<br />
because of a large enhancement due to the unique level structure, which<br />
exhibits almost degenerate P and metastable D states [1]. In order to<br />
learn and develop the spectroscopic techniques and trapping tool, we are<br />
working in parallel with barium, which has a level scheme very similar<br />
to radium. As a first step we will measure the lifetime of the metastable<br />
D-states as well as their hyperfine structure splitting. Once radium is<br />
available at KVI we will use our experience to do this spectroscopy with<br />
radium. We report on the status of the experiment and prospects for the<br />
26<br />
future.<br />
[1] V.A. Dzuba, V.V. Flambaum, and J.S.M. Ginges, Phys. Rev. A 61,<br />
062509 (2000); V.V. Flambaum, Phys. Rev. A 60, R2611, (1999).<br />
A 15.25 Do 14:00 Schellingstr. 3<br />
Fano’s model in an external periodic perturbation: Exact analytical<br />
solution — •N.B. Sangouard, R.G. Unanyan, L. Plimak,<br />
and M Fleischhauer — Fachbereich Physik, Universität Kaiserslautern,<br />
67653, Kaiserslautern, Germany<br />
Decay of a discrete state into continuum when the amplitude of the<br />
former is inverted periodically is investigated. A decaying ”Floquetresonance”<br />
solution of the Schrödinger equation valid for times large<br />
compared to the inversion period is identified. The decay rate, i.e., the<br />
imaginary part of the quasienergy of the ”Floquet resonance,” can be<br />
controlled by changing the period of the perturbation. Interestingly, the<br />
periodic inversions result in boundedness of the decay rate which stays finite<br />
for an arbitrarily strong coupling between the discrete state and continuum.<br />
This can have interesting applications in quantum computing,<br />
interferometry, and coherent control of reaction optical memory storage,<br />
dynamics.<br />
A 15.26 Do 14:00 Schellingstr. 3<br />
Abbremsung von SO2 mit zeitabhängigen elektrischen Feldern<br />
— •Sebastian Jung, Christian Lisdat und Eberhard Tiemann<br />
— Institut für Quantenoptik, Universität Hannover, Welfengarten 1,<br />
30167 Hannover, Germany<br />
Da sich die für Atome sehr effiziente Methode der Laserkühlung nicht<br />
allgemein auf Moleküle übertragen läßt, sind andere Ansätze zu deren<br />
Erzeugung notwendig. Experimentell realisiert wurden die Bildung von<br />
Molekülen aus kalten Atomen, Puffergaskühlung und die Abbremsung<br />
von polaren Molekülen in Teilchenstrahlen mit elektrischen Feldern.<br />
In unserem Experiment sollen SO2-Moleküle mit der zuletzt genannten<br />
Technik gebremst und gefangen werden. SO2 stellt aufgrund seiner großen<br />
Masse eine Herausforderung dar, bietet aber die Möglichkeit, Photodissoziation<br />
zur Erzeugung von kaltem O und SO zu nutzen. Beide Fragmente<br />
entstehen in Triplett-Zuständen, die magnetisch gefangen werden<br />
können. Photodissoziation in externen Feldern erlaubt die Untersuchung<br />
von Feshbachresonanzen.<br />
Der Stand der Experimente in Hinblick auf die Erzeugung eines kalten<br />
Strahls wird dargestellt und Simulationen für elektrostatische Linsen und<br />
den Abbremser beschrieben.<br />
A 15.27 Do 14:00 Schellingstr. 3<br />
Quasi-one-dimensional Bose and Femi gases under external confinement<br />
— •Doerte Blume 1 , Grigori Astrakharchik 2 , Stefano<br />
Giorgini 2 , and Brian Granger 3 — 1 Department of Physics,<br />
Washington State University, Pullman, Washington 99164-2814, USA —<br />
2 Dipartimento di Fisica, Universita di Trento and BEC-INFM, I-38050,<br />
Povo, Italy — 3 Department of Physics, Santa Clara University, California<br />
95053, USA<br />
Bose gases confined in highly-elongated harmonic traps are investigated<br />
over a wide range of interaction strengths using quantum Monte<br />
Carlo techniques. We find that the properties of these gases are well reproduced<br />
by a 1d model Hamiltonian with contact interactions. We point<br />
out the existence of a unitary regime, where the properties of the quasi-<br />
1d Bose gas become independent of the actual value of the 3d scattering<br />
length. In this unitary regime, the energy of the system is well described<br />
by a hard rod equation of state. The stability of quasi-1d Boses gases with<br />
positive and negative 3d scattering length is discussed. We contrast the<br />
behaviors of quasi-1d Bose gases with those of quasi-1d two-component<br />
Fermi gases and quasi-1d spin-polarized Fermi gases.<br />
A 15.28 Do 14:00 Schellingstr. 3<br />
Experiment for the preparation of an ultracold dense gas<br />
of Rydberg atoms — •Markus Reetz-Lamour 1 , Kilian<br />
Singer 1 , Thomas Amthor 1 , Simon Fölling 2 , and Matthias<br />
Weidemüller 1 — 1 Physikalisches Institut, Universität Freiburg, 79104<br />
Freiburg — 2 Johannes-Gutenberg-Universität, 55128 Mainz<br />
We report on an experiment, which is designed to investigate manybody<br />
effects in a dense gas of cold Rydberg atoms. Our setup consists<br />
of a very compact vacuum system where 10 8 87 Rb atoms at a density<br />
of 10 10 cm −3 are confined in a magneto-optical trap. The magnetic field<br />
is provided by coils inside the vacuum, the atoms are loaded from dispensers.<br />
After trapping and cooling down to 1µK with degenerate 3D<br />
Raman sideband cooling [1] the atoms are excited via a 2-photon transi-