Search results for " Ring"
showing 10 items of 478 documents
Laser cooling of relativistic heavy-ion beams for FAIR
2015
Laser cooling is a powerful technique to reduce the longitudinal momentum spread of stored relativistic ion beams. Based on successful experiments at the experimental storage ring at GSI in Darmstadt, of which we show some important results in this paper, we present our plans for laser cooling of relativistic ion beams in the future heavy-ion synchrotron SIS100 at the Facility for Antiproton and Ion Research in Darmstadt.
Vortex diffusion and vortex-line hysteresis in radial quantum turbulence
2014
Abstract We study the influence of vortex diffusion on the evolution of inhomogeneous quantized vortex tangles. A simple hydrodynamical model to describe inhomogeneous counterflow superfluid turbulence is used. As an illustration, we obtain solutions for these effects in radial counterflow of helium II between two concentric cylinders at different temperatures. The vortex diffusion from the inner hotter cylinder to the outer colder cylinder increases the vortex length density everywhere as compared with the non-diffusive situation. The possibility of hysteresis in the vortex line density under cyclical variations of the heat flow is explored.
Observation of sequential spin flips in quantum rings
2011
We observe strong signatures of spin flips in quantum rings exposed to external magnetic fields in the Coulomb blockade regime. The signatures appear as a pattern of lines corresponding to local reduction of conductance, and they cover a large range of magnetic fields and number of electrons. The sequence of lines, as well as other features in the conductance, can be captured by many-electron calculations within density-functional theory. The calculations show that most lines in the pattern correspond to sequential spin flips between filling factors 2 and 1. We believe that the ability to probe individual spin flips provides an important step toward precise spin control in quantum ring devi…
High-precision X-ray spectroscopy of highly-charged ions at the experimental storage ring using silicon microcalorimeters
2017
Abstract X-ray spectroscopy on highly charged heavy ions provides a sensitive test of quantum electrodynamics in very strong Coulomb fields. One limitation of the current accuracy of such experiments is the energy resolution of available X-ray detectors for energies up to 100 keV. To improve this accuracy, a novel detector concept, namely the concept of microcalorimeters, is exploited for this kind of measurements. The microcalorimeters used in the present experiments consist of silicon thermometers, ensuring a high dynamic range, and of absorbers made of high-Z material to provide high X-ray absorption efficiency. Recently, besides an earlier used detector, a new compact detector design, h…
Compact Topological Quantum Groups
1995
Using vector spaces topologies we unify the different models of quantum groups. Duality and reflexivity are built in. The Drinfeld deformation can be extended to the distributions on a simple compact Lie group and dually to the infinitely differentiable functions. The topological quantum double is similarly defined and a uniqueness result is obtained.
A large-area modular electromagnetic shower detector for the CERN intersecting storage rings
1979
The authors describe the design and performances large-area (13 m/sup 2/) shower detector built for an experiment at the CERN ISR to detect electrons and gamma rays with energies up to 4 GeV. The main characteristics of the detector are: a) linearity of the energy response from 0.5 to 4 GeV; b) good energy, time and space resolutions; c) modularity of the mechanical assembly; d) low cost of construction. (3 refs).
Evidence of a Resonant Structure in the Cross Section between 4.05 and 4.60 GeV
2019
The cross section of the process e^{+}e^{-}→π^{+}D^{0}D^{*-} for center-of-mass energies from 4.05 to 4.60 GeV is measured precisely using data samples collected with the BESIII detector operating at the BEPCII storage ring. Two enhancements are clearly visible in the cross section around 4.23 and 4.40 GeV. Using several models to describe the dressed cross section yields stable parameters for the first enhancement, which has a mass of 4228.6±4.1±6.3 MeV/c^{2} and a width of 77.0±6.8±6.3 MeV, where the first uncertainties are statistical and the second ones are systematic. Our resonant mass is consistent with previous observations of the Y(4220) state and the theoretical prediction of a D…
Continuum and discrete excitation spectrum of single quantum rings
2005
Photoluminescence and excitation of the photoluminescence spectroscopy has been performed in single InGaAs self-assembled quantum rings embedded in a field effect structure device. To determine their electronic structure, bias-dependent optical transitions have been analyzed both, for individual quantum rings, and for the averaged ensemble. Our results are compared with a theoretical model, and also with results reported by other authors studying similar nanostructures.
Frontiers of Heavy - Ion Physics and Superheavy Elements
2003
This contribution will focus on three topics of GSI nuclear structure research: super heavy elements, direct mass measurements in the storage ring, and the measurement of spallation cross section in reversed kinematics. The GSI project for an extended synchrotron facility will be outlined.
Laser spectroscopy at the experimental storage ring - an overview
2012
We present an overview of laser spectroscopy experiments at the experimental storage ring of GSI in Darmstadt, which have been and will be performed in the near future.