Search results for " atom"
showing 10 items of 1526 documents
On the effect of excited states in lattice calculations of the nucleon axial charge
2017
Excited-state contamination is one of the dominant uncertainties in lattice calculations of the nucleon axial-charge, $g_A$. Recently published results in leading-order chiral perturbation theory (ChPT) predict the excited-state contamination to be independent of the nucleon interpolator and positive. However, empirical results from numerical lattice calculations show negative contamination (downward curvature), indicating that present-day calculations are not in the regime where the leading-order ChPT predictions apply. In this paper we show that, under plausible assumptions, one can reproduce the behavior of lattice correlators by taking into account final-state $N \pi$ interactions, in p…
Recent progress in laser spectroscopy of the actinides
2020
The interest to perform laser spectroscopy in the heaviest elements arises from the strong impact of relativistic effects, electron correlations and quantum electrodynamics on their atomic structure. Once this atomic structure is well understood, laser spectroscopy also provides access to nuclear properties such as spins, mean square charge radii and electromagnetic moments in a nuclear-model independent way. This is of particular interest for the heaviest actinides around $N = 152$, a region of shell stabilized deformed nuclei. The experimental progress of laser spectroscopy in this region benefitted from continuous methodological and technical developments such as the introduction of buff…
Neutrino mixing and CP-violation
2000
The prospects of measuring the leptonic angles and CP-odd phases at a neutrino factory are discussed in two scenarios: 1) three active neutrinos as indicated by the present ensemble of atmospheric plus solar data; 2) three active plus one sterile neutrino when the LSND signal is also taken into account. For the latter we develop one and two mass dominance approximations. The appearance of wrong sign muons in long baseline experiments and tau leptons in short baseline ones provides the best tests of CP-violation in scenarios 1) and 2), respectively.
Longitudinal phase space reconstruction for a heavy ion accelerator
2020
At the GSI Helmholtzzentrum f\"ur Schwerionenforschung (GSI) in Darmstadt, Germany, a prototype cryomodule (advanced demonstrator) for the superconducting (SC) continuous wave (CW) Helmholtz Linear Accelerator (HELIAC) is under construction. A transport line, comprising quadrupole lenses, rebuncher cavities, beam correctors, and adequate beam instrumentation has been built to deliver the beam from the GSI 1.4 MeV/u High Charge Injector (HLI) to the advanced demonstrator, which offers a test environment for SC CW multigap cavities. In order to achieve proper phase space matching, the beam from the HLI must be characterized in detail. In a dedicated machine experiment the bunch shape has been…
Non-standard neutrino oscillations: perspective from unitarity triangles
2021
We formulate an alternative approach based on unitarity triangles to describe neutrino oscillations in presence of non-standard interactions (NSI). Using perturbation theory, we derive the expression for the oscillation probability in case of NSI and cast it in terms of the three independent parameters of the leptonic unitarity triangle (LUT). The form invariance of the probability expression (even in presence of new physics scenario as long as the mixing matrix is unitary) facilitates a neat geometric view of neutrino oscillations in terms of LUT. We examine the regime of validity of perturbative expansions in the NSI case and make comparisons with approximate expressions existing in liter…
Thousandfold improvement in the measured antiproton mass
1990
Comparisons of antiproton and proton cyclotron frequencies yield the ratio of inertial masses M(p¯)/M(p)=0.999 999 977 ±0.000 000 042. The fractional uncertainty of 4×10−8 is 1000 times more accurate than previous measurements of this ratio using exotic atoms and is the most precise test of CPT invariance with baryons. Independent comparisons to electrons yield the mass ratios M(p¯)/M(e−)=1836.152 660±0.000 083 and M(p)/M(e−) =1836.152 680±0.000 088. Cryogenic antiprotons (near 4 K) stored in a Penning trap for 2 months establish directly a lifetime greater than 3.4 months.
A Relativistic Eikonal Model for the Dissociation of One-Neutron Halo Nuclei at High Energy
2019
info:eu-repo/semantics/published
Neutrino mean free path in neutron matter with Brussels-Montreal Skyrme functionals
2016
We calculate the neutrino mean free path in cold neutron matter with some modern Brussels-Montreal functionals. The three typical functionals used in this article produce quite different results implying a possible impact on the cooling mechanism of neutron stars.
Preaccelerator concepts for an energy-recovering superconducting accelerator
2021
In this paper we compare two concepts of a preaccelerator for the energy-recovery linac MESA: a hybrid injector that combines normal conducting and superconducting technology and a fully normal conducting injector. The particle source delivers polarized electrons at 100 keV. Thus the first accelerating section has to be of a graded-β kind. The graded-β section is designed with a final energy exceeding 1 MeV so TESLA-type nine-cell resonators can be used as superconducting cavities. The final energy of the preaccelerator shall be 5 MeV to avoid neutron production in the beam dump of the energy-recovery linac.
Experiments with Exotic Atoms and Exotic Nuclei at GSI, Recent Developments and Future Prospects
2004
Results and new developments with exotic atoms and exotic nuclei are presented from recent experiments at GSI. The proposed European inflight facility at GSI will open up new fields of outstanding research and will simultaneously access unknown regions of nuclei with new properties. A new generation of precision experiments will be performed with stored exotic nuclei, whereby nuclear reactions with an internal target and electron scattering in a small electron-ion collider will be a great challenge.