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Kisel I.,Goethe University Frankfurt | Kisel I.,FIAS Frankfurt Institute for Advanced Studies | Kisel I.,Helmholtz Center for Heavy Ion Research
EPJ Web of Conferences | Year: 2016

The future heavy-ion experiment CBM (FAIR/GSI, Darmstadt, Germany) will focus on measurement of very rare probes at interaction rates up to 10 MHz with data flow of up to 1 TB/s. The beam will provide free stream of beam particles without bunch structure. That requires full online event reconstruction and selection not only in space, but also in time, so-called 4D event building and selection. The FLES (First-Level Event Selection) reconstruction and selection package consists of several modules: track finding, track fitting, short-lived particles finding, event building and event selection. A time-slice is reconstructed in parallel between cores within a same CPU, thus minimizing the communication between CPUs. After all tracks are found and fitted in 4D, they are collected into clusters of tracks originated from common primary vertices, which then are fitted, thus identifying 4D interaction points registered within the time-slice. Secondary tracks are associated with primary vertices according to their estimated production time. After that, short-lived particles are found and the full event building process is finished. The last stage of the FLES package is the selection of events according to the requested trigger signatures. © Owned by the authors.


Fritzsche S.,Helmholtz Center for Heavy Ion Research | Fritzsche S.,FIAS Frankfurt Institute for Advanced Studies | Surzhykov A.,Helmholtz Center for Heavy Ion Research | Surzhykov A.,University of Heidelberg | And 4 more authors.
New Journal of Physics | Year: 2012

The electron emission of highly charged ions has been reanalyzed with the goal of separating the magnetic and retardation contributions to the electron-electron (e-e) interaction from the static Coulomb repulsion in strong fields. A remarkable change in the electron angular distribution due to the relativistic terms in the e-e interaction is found, especially for the autoionization of beryllium-like projectiles, following a 1s → 2p 3/2 Coulomb excitation in collision with some target nuclei. For low-energetic, high-Z projectiles with Tp < 10MeVu -1, a diminished (electron) emission in the forward direction as well as oscillations in the electron angular distribution due to the magnetic and retarded interactions are predicted for the autoionization of the 1s2s22p3/2 3P2 resonance into the 1s 22s 2S 1/2 ground and the 1s 22p 2P 1/2 excited levels of the finally lithium-like ions, and in contrast to a pure Coulomb repulsion between the bound and emitted electrons. The proposed excitation-autoionization process can be observed at existing storage rings and will provide a novel insight into the dynamics of electrons in strong fields. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.


Kellerbauer A.,Max Planck Institute for Nuclear Physics | Canali C.,Max Planck Institute for Nuclear Physics | Fischer A.,Max Planck Institute for Nuclear Physics | Warring U.,Max Planck Institute for Nuclear Physics | And 2 more authors.
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

The isotope shift of the bound-bound electric dipole transition at 1162.75 nm in the osmium anion was measured by high-precision collinear laser spectroscopy. The transition was observed in all naturally occurring isotopes, including 184Os- with a natural abundance of 0.02%. We combined the data with our prior measurements of the hyperfine structure in 187Os- and 189Os- and used them to determine experimental values for the isotope shift coefficients. The normal mass shift, specific mass shift, and field shift coefficients were found to be MNMS=141.4 GHz u, M SMS=2.4(12.6) THz u, and F=16.2(9.9) GHz fm-2, respectively. Theoretical values for the MSMS and F parameters were calculated based on a series of relativistic configuration interaction computations and a Fermi-like charge distribution and found to be in good agreement with the experimental values. © 2011 American Physical Society.


Matula O.,University of Heidelberg | Matula O.,Helmholtz Center for Heavy Ion Research | Fritzsche S.,Helmholtz Center for Heavy Ion Research | Fritzsche S.,FIAS Frankfurt Institute for Advanced Studies | And 3 more authors.
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

We investigate the angular correlations between the photons emitted in the dielectronic recombination (DR) of initially hydrogenlike heavy ions. The theoretical analysis is performed based on a density-matrix approach and Dirac's relativistic theory. Special emphasis has been placed upon the effects of the higher-order, nondipole terms in the expansion of the electron-photon interaction. To illustrate these effects, we present and discuss detailed calculations for K-LL DR of initially hydrogenlike xenon, gold, and uranium. These computations show that the angular correlations are significantly affected by interference between the leading electric-dipole (E1) and the magnetic-quadrupole (M2) transitions. © 2011 American Physical Society.


Fratini F.,University of Heidelberg | Fratini F.,Helmholtz Center for Heavy Ion Research | Tichy M.C.,Albert Ludwigs University of Freiburg | Jahrsetz T.,University of Heidelberg | And 6 more authors.
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

A theoretical study of the polarization entanglement of two photons emitted in the decay of metastable ionic states is performed within the framework of density-matrix theory and second-order perturbative approach. Particular attention is paid to relativistic and nondipole effects that become important for medium- and high-Z ions. To analyze these effects, the degree of entanglement is evaluated both in the dipole approximation and within rigorous relativistic theory. Detailed calculations are performed for the two-photon 2s1/2→1s1/2 transition in hydrogenlike ions as well as for the 1s1/22s1/21S0→1s1/221S 0, 1s1/22s1/23S1→1s1/221S 0, and 1s1/22p1/23P0→1s1/ 221S0 transitions in heliumlike ions. © 2011 American Physical Society.


Li J.,Free University of Colombia | Naze C.,Free University of Colombia | Godefroid M.,Free University of Colombia | Fritzsche S.,Helmholtz Center for Heavy Ion Research | And 4 more authors.
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

It was recently shown that dielectronic recombination measurements can be used for accurately inferring changes in the nuclear mean-square charge radii of highly charged lithiumlike neodymium. To make use of this method to derive information about the nuclear charge distribution for other elements and isotopes, accurate electronic isotope shift parameters are required. In this work, we calculate and discuss the relativistic mass- and field-shift factors for the two 2s2S 1/2-2p2P1/2,3/2o transitions along the lithium isoelectronic sequence. Based on the multiconfiguration Dirac-Hartree-Fock method, the electron correlation and the Breit interaction are taken into account systematically. The analysis of the isotope shifts for these two transitions along the isoelectronic sequence demonstrates the importance and competition between the mass shifts and the field shifts. © 2012 American Physical Society.


Fritzsche S.,Helmholtz Center for Heavy Ion Research | Fritzsche S.,FIAS Frankfurt Institute for Advanced Studies | Fritzsche S.,University of Oulu
Computer Physics Communications | Year: 2012

During the past decade, the Ratip program has been developed to calculate the electronic structure and properties of atoms and ions. This code, which is now organized as a suite of programs, provides a powerful platform today to generate and evaluate atomic data for open-shell atoms, including level energies and energy shifts, transition probabilities, Auger parameters as well as a variety of excitation, ionization and recombination amplitudes and cross sections. Although the Ratip program focus on properties with just one electron within the continuum, recent emphasis was placed also on second-order processes as well as on the combination of different types of transition amplitudes in order to explore more complex spectra. Here, I present and discuss the (design of the) Ratip program and make available a major part of the code for public use. Selected examples show a few of its possible applications, while reference is made to a much wider range of computations as supported by the program. The Ratip program has been developed as a scalar Fortran 90/95 code and provides a simple make feature which help port the code to different platforms and architectures. © 2012 Elsevier B.V. All rights reserved.


Cheal B.,University of Manchester | Cocolios T.E.,CERN | Fritzsche S.,Helmholtz Center for Heavy Ion Research | Fritzsche S.,FIAS Frankfurt Institute for Advanced Studies
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

Nuclear mean-square charge radii of radioactive isotopes are obtained from isotope-shift measurements using laser spectroscopy. To extract the values of δr2 the atomic field and mass shift factors need to be evaluated. We here summarize the currently available experimental and theoretical techniques for calculating the atomic field and mass shift factors for complex, open-shell atoms, including the 5s21S 0-4d5p1P 1 and 4d5s3D 2-4d5p3P 1 transitions for singly charged yttrium (Z=39). © 2012 American Physical Society.


Kisel I.,Goethe University Frankfurt | Kisel I.,FIAS Frankfurt Institute for Advanced Studies | Kisel I.,Helmholtz Center for Heavy Ion Research
EPJ Web of Conferences | Year: 2015

Future FAIR experiments have to deal with very high input rates, large track multiplicities, make full event reconstruction and selection on-line on a large dedicated computer farm equipped with heterogeneous many-core CPU/GPU compute nodes. To develop efficient and fast algorithms, which are optimized for parallel computations, is a challenge for the groups of experts dealing with the HPC computing. Here we present and discuss the status and perspectives of the data reconstruction and physics analysis software of one of the future FAIR experiments, namely, the CBM experiment. © Owned by the authors, published by EDP Sciences, 2015.


Gumberidze A.,Helmholtz Center for Heavy Ion Research | Gumberidze A.,FIAS Frankfurt Institute for Advanced Studies
Physica Scripta | Year: 2013

The new international accelerator Facility for Antiproton and Ion Research (FAIR) which is currently under construction in Darmstadt has key features that offer a wide range of exciting new opportunities in the field of atomic physics and related fields. The facility will provide highest intensities of relativistic beams of both stable and unstable heavy nuclei, in combination with the strong electromagnetic fields generated by high-power lasers, thus allowing to widen atomic physics research into completely new domains. In the current contribution, a short overview of the SPARC (Stored Particle Atomic physics Research Collaboration) research programme at the FAIR facility is given. Furthermore, we present the current strategy for the realization of the envisioned SPARC physics programme at the modularized start version of the FAIR facility. © 2013 The Royal Swedish Academy of Sciences.

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