| 1. |
- Winters, D. F. A., et al.
(författare)
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Laser spectroscopy of the (1s(2)2s2p) (3)P(0)-(3)P(1) level splitting in Be-like krypton
- 2011
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Ingår i: Physica Scripta. - 0031-8949 .- 1402-4896. ; T144, s. 014013-
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Tidskriftsartikel (refereegranskat)abstract
- Heavy few-electron ions, such as He-, Li- and Be-like ions, are ideal atomic systems to study the effects of correlation, relativity and quantum electrodynamics. Very recently, theoretical and experimental studies of these species achieved a considerable improvement in accuracy. Be-like ions are interesting because their first excited state, i.e. (1s(2)2s2p) (3)P(0), has an almost infinite lifetime (tau(0)) in the absence of nuclear spin (I), as it can only decay by a two-photon E1M1 transition to the (1s(2)2s(2)) (1)S(0) ground state. In addition, the energy difference between the 3P0 and the next higher-lying (3)P(1) state is expected to remain almost completely unaffected by QED effects, and should thus be dominated by the effects of correlation and relativity. Therefore, we want to determine the (1s(2)2s2p) (3)P(0)-(3)P(1) level splitting in Be-like krypton ((84)Kr(32+)), which has I = 0, by means of laser spectroscopy at the experimental storage ring at GSI. In such an experiment, the energy splitting can be obtained with very good accuracy and can be compared with recent calculations.
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| 2. |
- Durante, M., et al.
(författare)
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All the fun of the FAIR: fundamental physics at the facility for antiproton and ion research
- 2019
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Ingår i: Physica Scripta. - : IOP Publishing. - 1402-4896 .- 0031-8949. ; 94:3
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Forskningsöversikt (refereegranskat)abstract
- The Facility for Antiproton and Ion Research (FAIR) will be the accelerator-based flagship research facility in many basic sciences and their applications in Europe for the coming decades. FAIR will open up unprecedented research opportunities in hadron and nuclear physics, in atomic physics and nuclear astrophysics as well as in applied sciences like materials research, plasma physics and radiation biophysics with applications towards novel medical treatments and space science. FAIR is currently under construction as an international facility at the campus of the GSI Helmholtzzentrum for Heavy-Ion Research in Darmstadt, Germany. While the full science potential of FAIR can only be harvested once the new suite of accelerators and storage rings is completed and operational, some of the experimental detectors and instrumentation are already available and will be used starting in summer 2018 in a dedicated research program at GSI, exploiting also the significantly upgraded GSI accelerator chain. The current manuscript summarizes how FAIR will advance our knowledge in various research fields ranging from a deeper understanding of the fundamental interactions and symmetries in nature to a better understanding of the evolution of the Universe and the objects within.
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| 3. |
- Gumberidze, A., et al.
(författare)
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Electron- and proton-impact excitation of heliumlike uranium in relativistic collisions
- 2019
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Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - 2469-9926 .- 2469-9934. ; 99:3
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the K-shell excitation of He-like uranium (U90+) in relativistic collisions with hydrogen and argon atoms. Performing measurements with different targets, as well as with different collision energies, enabled us to explore the proton- (nucleus-) impact excitation as well as the electron-impact excitation process for the heaviest He-like ion. The large fine-structure splitting in uranium allowed us to partially resolve excitation into different L-shell levels. State-of-the-art relativistic calculations which include excitation mechanisms due to the interaction with both protons (nucleus) and electrons are in good agreement with the experimental findings. Moreover, our experimental data clearly demonstrate the importance of including the generalized Breit interaction in the treatment of the electron-impact excitation process.
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| 4. |
- Gumberidze, A., et al.
(författare)
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Electron- and Proton-Impact Excitation of Hydrogenlike Uranium in Relativistic Collisions
- 2013
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 110:21, s. 213201-
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Tidskriftsartikel (refereegranskat)abstract
- The K shell excitation of H-like uranium (U91+) in relativistic collisions with different gaseous targets has been studied at the experimental storage ring at GSI Darmstadt. By performing measurements with different targets as well as with different collision energies, we were able to observe for the first time the effect of electron-impact excitation (EIE) process in the heaviest hydrogenlike ion. The large fine-structure splitting in H-like uranium allowed us to unambiguously resolve excitation into different L shell levels. State-of-the-art calculations performed within the relativistic framework which include excitation mechanisms due to both protons (nucleus) and electrons are in good agreement with the experimental findings. Moreover, our experimental data clearly demonstrate the importance of including the generalized Breit interaction in the treatment of the EIE process.
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| 5. |
- Maiorova, A. V., et al.
(författare)
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Polarization studies on the two-step radiative recombination of highly charged, heavy ions
- 2009
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Ingår i: Journal of Physics B. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 42:12
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Tidskriftsartikel (refereegranskat)abstract
- Radiative recombination of a free electron into an excited state of a bare, high-Z ion is studied, together with its subsequent decay, within the framework of the density matrix theory and Dirac's relativistic equation. Special attention is paid to the polarization and angular correlations between the recombination and the decay photons. In order to perform a systematic analysis of these correlations the general expression for the double-differential recombination cross section is obtained by making use of the resonance approximation. Based on this expression, detailed computations for the linear polarization of x-ray photons emitted in the (e, 2 gamma) two-step recombination of uranium ions U92+ are carried out for a wide range of projectile energies.
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| 6. |
- Sguazzin, M., et al.
(författare)
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Indirect measurements of neutron -induced reaction cross sections at heavy -ion storage rings
- 2023
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Ingår i: 15TH INTERNATIONAL CONFERENCE ON NUCLEAR DATA FOR SCIENCE AND TECHNOLOGY, ND2022. - 2100-014X. ; 284
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Konferensbidrag (refereegranskat)abstract
- Neutron-induced reaction cross sections of unstable nuclei are essential for understanding the synthesis of heavy elements in stars and for applications in nuclear technology. However, their measurement is very complicated due to the radioactivity of the targets involved. We propose to circumvent this problem by using the surrogate reaction method in inverse kinematics, where the nucleus formed in the neutroninduced reaction of interest is produced by a reaction involving a radioactive heavy -ion beam and a stable, light target nucleus. The probabilities as a function of the compound -nucleus excitation energy for y -ray emission, neutron emission and fission, which can be measured with the surrogate reaction, are particularly useful to constrain model parameters and to obtain more accurate predictions of the neutron-induced reaction cross sections of interest. Yet, the full development of the surrogate method is hampered by numerous longstanding target issues, which can be solved by combining surrogate reactions with the unique and largely unexplored possibilities at heavy -ion storage rings. In this contribution, we describe the developments we are carrying out to measure for the first time simultaneously y-ray emission, neutron emission and fission probabilities at the storage rings of the GSI/FAIR facility. In particular, we will present the first results of the proof of principle experiment, which we performed in June 2022 at the Experimental Storage Ring (ESR)
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| 7. |
- Stoehlker, Th., et al.
(författare)
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APPA at FAIR : From fundamental to applied research
- 2015
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 235, s. 680-685
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Tidskriftsartikel (refereegranskat)abstract
- FAIR with its intense beams of ions and antiprotons provides outstanding and worldwide unique experimental conditions for extreme matter research in atomic and plasma physics and for application oriented research in biophysics, medical physics and materials science. The associated research programs comprise interaction of matter with highest electromagnetic fields, properties of plasmas and of solid matter under extreme pressure, density, and temperature conditions, simulation of galactic cosmic radiation, research in nanoscience and charged particle radiotherapy. A broad variety of APPA-dedicated facilities including experimental stations, storage rings, and traps, equipped with most sophisticated instrumentation will allow the APPA community to tackle new challenges. The worldwide most intense source of slow antiprotons will expand the scope of APPA related research to the exciting field of antimatter.
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| 8. |
- Thorn, D. B., et al.
(författare)
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Polarization and anisotropic emission of K-shell radiation from heavy few electron ions
- 2011
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Ingår i: Canadian journal of physics (Print). - 0008-4204 .- 1208-6045. ; 89:5, s. 513-519
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Tidskriftsartikel (refereegranskat)abstract
- The population of magnetic sublevels in hydrogen-like uranium ions has been investigated in relativistic ion-atom collisions by observing the subsequent X-ray emission. Using the gas target at the experimental storage ring facility we observed the angular emission of Lyman-alpha radiation from hydrogen-like uranium ions. The alignment parameter for three different interaction energies was measured and found to agree well with theory. In addition, the use of different gas targets allowed for the electron-impact excitation process to be observed.
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