| 1. |
- Lestinsky, M., et al.
(författare)
-
Physics book: CRYRING@ESR
- 2016
-
Ingår i: European Physical Journal: Special Topics. - : Springer Science and Business Media LLC. - 1951-6401 .- 1951-6355. ; 225:5, s. 797-882
-
Forskningsöversikt (refereegranskat)abstract
- The exploration of the unique properties of stored and cooled beams of highly-charged ions as provided by heavy-ion storage rings has opened novel and fascinating research opportunities in the realm of atomic and nuclear physics research. Since the late 1980s, pioneering work has been performed at the CRYRING at Stockholm (Abrahamsson et al. 1993) and at the Test Storage Ring (TSR) at Heidelberg (Baumann et al. 1988). For the heaviest ions in the highest charge-states, a real quantum jump was achieved in the early 1990s by the commissioning of the Experimental Storage Ring (ESR) at GSI Helmholtzzentrum für Schwerionenforschung (GSI) in Darmstadt (Franzke 1987) where challenging experiments on the electron dynamics in the strong field regime as well as nuclear physics studies on exotic nuclei and at the borderline to atomic physics were performed. Meanwhile also at Lanzhou a heavy-ion storage ring has been taken in operation, exploiting the unique research opportunities in particular for medium-heavy ions and exotic nuclei (Xia et al. 2002).
|
|
| 2. |
- Herdrich, M. O., et al.
(författare)
-
Application of a metallic-magnetic calorimeter for high-resolution x-ray spectroscopy of Fe at an EBIT
- 2024
-
Ingår i: Journal of Physics B. - 0953-4075 .- 1361-6455. ; 57:8
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, we present an experiment conducted at the S-EBIT-I ion trap of GSI. It involved the study of ion-electron collisions of Fe and Ba ions in various charge states with the electron beam. Characteristic x-ray radiation emitted during the continuous interaction was recorded utilizing an energy-dispersive maXs-30 detector based on metallic-magnetic calorimeter (MMC) technology. Optimizations to the applied sensitivity-drift correction and energy calibration procedures significantly improved the achieved energy resolution compared to previous applications of a similar detector. This made it possible to individually resolve and identify overlapping x-ray lines of iron and barium in a wide spectral range. As a demonstration of the outstanding detector performance, we used the recorded spectral data to extract an estimate of the charge state distribution of Fe ions in the trap. This experiment campaign marks an important milestone in the ongoing effort to enable the deployment of MMC detectors for future high-precision measurements in fundamental physics experiments.
|
|
| 3. |
- Maccari, Ilaria, et al.
(författare)
-
Interplay of spin waves and vortices in the two-dimensional XY model at small vortex-core energy
- 2020
-
Ingår i: Physical Review B. - : American Physical Society (APS). - 2469-9950 .- 2469-9969. ; 102:10
-
Tidskriftsartikel (refereegranskat)abstract
- The Berezinskii-Kosterlitz-Thouless (BKT) mechanism describes universal vortex unbinding in many two-dimensional systems, including the paradigmatic XY model. However, most of these systems present a complex interplay between excitations at different length scales that complicates theoretical calculations of nonuniversal thermodynamic quantities. These difficulties may be overcome by suitably modifying the initial conditions of the BKT flow equations to account for noncritical fluctuations at small length scales. In this work, we perform a systematic study of the validity and limits of this two-step approach by constructing optimised initial conditions for the BKT flow. We find that the two-step approach can accurately reproduce the results of Monte Carlo simulations of the traditional XY model. To systematically study the interplay between vortices and spin-wave excitations, we introduce a modified XY model with increased vortex fugacity. We present large-scale Monte Carlo simulations of the spin stiffness and vortex density for this modified XY model and show that even at large vortex fugacity, vortex unbinding is accurately described by the nonperturbative functional renormalization group.
|
|
| 4. |
- Maccari, Ilaria, et al.
(författare)
-
Vortex supersolid in the XY model with tunable vortex fugacity
- 2023
-
Ingår i: Journal of Physics. - 0953-8984 .- 1361-648X. ; 35:33
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we investigate the XY model in the presence of an additional potential term that independently tunes the vortex fugacity favouring their nucleation. By increasing the strength of this term and thereby the vortex chemical potential µ, we observe significant changes in the phase diagram with the emergence of a normal vortex-antivortex lattice as well as a superconducting vortex-antivortex crystal (lattice supersolid) phase. We examine the transition lines between these two phases and the conventional non-crystalline one as a function of both the temperature and the chemical potential. Our findings suggest the possibility of a peculiar tricritical point where second-order, first-order, and infinite-order transition lines meet. We discuss the differences between the present phase diagram and previous results for two-dimensional Coulomb gas models. Our study provides important insights into the behaviour of the modified XY model and opens up new possibilities for investigating the underlying physics of unconventional phase transitions.
|
|
