Search results for "Trap"
showing 10 items of 2144 documents
Individual and center-of-mass resonances in the motional spectrum of an electron cloud in a Penning trap
2002
We have examined experimentally the motional spectrum of an electron cloud confined in a Penning trap. When the axial oscillation is excited by a radio frequency field the resonance exhibits a double structure. Both components depend differently on the number of trapped electrons and have different shape and width. We conclude that one of them corresponds to the excitation of the individual electrons while the other is the center-of-mass mode of the cloud. The threshold behaviour of the center-of-mass resonance suggests that it is a parametric instability of a Mathieu type equation of motion.
Strange Electromagnetic Form Factors of the Nucleon with Nf=2+1 O(a) -Improved Wilson Fermions
2019
We present results for the strange contribution to the electromagnetic form factors of the nucleon computed on the coordinated lattice simulation ensembles with N_{f}=2+1 flavors of O(a)-improved Wilson fermions and an O(a)-improved vector current. Several source-sink separations are investigated in order to estimate the excited-state contamination. We calculate the form factors on six ensembles with lattice spacings in the range of a=0.049-0.086 fm and pion masses in the range of m_{π}=200-360 MeV, which allows for a controlled chiral and continuum extrapolation. In the computation of the quark-disconnected contributions, we employ hierarchical probing as a variance-reduction technique.
Recent Developments in one and two Pion Production in Elementary Reactions and Few-Body Systems
1995
In this talk we cover several issues concerning pion production. The first one is the pp → ppπ 0 reaction where an alternative explanation based on the off shell extrapolation of the πN amplitude is offered. A recent model for the γN → ππN reaction is presented and a new kind of exchange current is constructed from it which allows one to address problems like double ∆ photoproduction from the deuteron. Finally the (γ, ππ) reaction in nuclei is studied and shown to be highly sensitive to the renormalization of the pions in nuclei.
Precise Determination of the UnperturbedB8Neutrino Spectrum
2012
A measurement of the final state distribution of the B-8 beta decay, obtained by implanting a 8B beam in a double-sided silicon strip detector, is reported here. The present spectrum is consistent with a recent independent precise measurement performed by our collaboration at the IGISOL facility, Jyvaskyla [O. S. Kirsebom et al., Phys. Rev. C 83, 065802 ( 2011)]. It shows discrepancies with previously measured spectra, leading to differences in the derived neutrino spectrum. Thanks to a low detection threshold, the neutrino spectrum is for the first time directly extracted from the measured final state distribution, thus avoiding the uncertainties related to the extrapolation of R-matrix fi…
Isotope separation by nonlinear resonances in a Paul trap
1996
Deviations from the ideal quadrupole potential in a Paul ion trap create nonlinear resonances at certain operating points inside the stability diagram, where in the absence of potential pertubations storing times are very long. In the presence of those pertubations, however, the ions are lost from the trap. Since these resonances are mass dependent and the mass resolution is of the order of 100 it can be used to separate isotopes of a given element by choosing suitable trap operating conditions. Experiments on a natural mixture of Eu+ ions of mass 151 and 153 show that in a simple way, by proper choice of the operating point, the ions can be completely separated and laser-induced optical sp…
A novel cooling scheme for antiprotons
2006
We propose a novel technique which uses laser-cooled negative osmium ions for sympathetic cooling of antiprotons. Temperatures down to the sub-millikelvin range might be achievable. These antiprotons could be used to form antihydrogen at ultra-cold temperatures, thus allowing efficient magnetic trapping of antihydrogen for high-resolution laser spectroscopy. Antihydrogen at sub-millikelvin temperatures might also enable first direct measurements of the gravitational acceleration of antimatter. Currently, no other technique exists which allows the cooling of large numbers of antiprotons to temperatures below that of the surrounding trap.
Quantum-state-selective decay spectroscopy of Ra213
2017
An experimental scheme combining the mass resolving power of a Penning trap with contemporary decay spectroscopy has been established at GSI Darmstadt. The Universal Linear Accelerator (UNILAC) at GSI Darmstadt provided a $^{48}\mathrm{Ca}$ beam impinging on a thin $^{170}\mathrm{Er}$ target foil. Subsequent to velocity filtering of reaction products in the Separator for Heavy Ion reaction Products (SHIP), the nuclear ground state of the $5n$ evaporation channel $^{213}\mathrm{Ra}$ was mass-selected in SHIPTRAP, and the $^{213}\mathrm{Ra}$ ions were finally transferred into an array of silicon strip detectors surrounded by large composite germanium detectors. Based on comprehensive geant4 s…
Nonlinear collective oscillations of an ion cloud in a Paul trap
1997
In an experiment using a Paul trap, we create a ${\mathrm{H}}_{2}^{+}$ ion cloud by electron ionization of the background gas at ${10}^{\ensuremath{-}9}$-mbar residual pressure. Exciting the ions parametrically at twice the frequency of the secular motion of ions in the $r$ or $z$ direction, we observe a narrow resonance at some distance from the motional resonance center if the amplitude of the exciting field exceeds a threshold value. The threshold value decreases with increasing ion number. Since the narrow resonance does not shift with ion number, we interpret it as a collective resonance of the center of mass of the ion cloud. The resonance shape exhibits the typical form of a driven a…
SpecTrap: precision spectroscopy of highly charged ions—status and prospects
2013
We present the status of the SpecTrap experiment currently being commissioned in the framework of the HITRAP project at GSI, Darmstadt, Germany. SpecTrap is a cryogenic Penning trap experiment dedicated to high-accuracy laser spectroscopy of highly charged ions (HCI) near rest. Determination of fine structure and hyperfine structure splittings in HCI with an expected relative spectral resolution of 10−7 will offer the possibility to test quantum electrodynamics in strong fields with unprecedented accuracy. Recently, we have demonstrated trapping and laser Doppler cooling of singly charged magnesium ions in SpecTrap. We report on the status of the experimental apparatus, measurements and pre…
Resolution of Single Spin Flips of a Single Proton
2013
The spin magnetic moment of a single proton in a cryogenic Penning trap was coupled to the particle's axial motion with a superimposed magnetic bottle. Jumps in the oscillation frequency indicate spin-flips and were identified using a Bayesian analysis.