Annual Meeting of the ErUM-FSP APPA 2026

This talk will give an overview on the federal ministry of research, technology and space and the project management agency PT.DESY. The relevant strategies and priorities, especially the funding framework ErUM and the high-tech agenda, and the current activities in the ErUM field “Particles” will be presented.

In my presentation, I report on the current status of SPARC, the Stored Particles Atomic physics Research Collaboration. First, I will give a brief overview of the FAIR facilities currently and in near future used in the SPARC experiments. Then, I will present some examples of scientific results from recent measurement campaigns at CRYRING, ESR, and HITRAP. I will also provide a brief...

The High Energy Density Science at FAIR (HED@FAIR) collaboration is continuing to prepare for the experimental program of First Science ++ in the APPA cave. Experiments at the existing GSI facilities play a vital role in preparing the experiments and in the commissioning and testing of experimental equipment. In my presentation I will give an overview of the recent experimental activities and...

During the user run 2025 essentially all operation modes of the ESR were used and highlights will be presented: electron cooling, stochastic cooling, stacking, internal experiments and extracted beam experiments with beam delivery to CryRing and HITRAP. The new LSA control system is consolidated in the sense that it offers practically all operation modes covered by the decommissioned legacy...

Electron cooling is the only means of ion-beam cooling available at CRYRING@ESR. For precision experiments on stored ions, the range of available beam parameters is thus confined by technical and physical limits of the electron cooler in addition to those of the ring itself. Since recommissioning of the cooler at GSI/FAIR, its availability has steadily improved and new technical capabilities...

The HITRAP (Highly charged Ion TRAP) facility located at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt provides the unique ability to decelerate heavy, accelerator-produced highly charged ions (HCI) down to 6 keV/nucleon and cool to eV equivalent temperature. A two-stage decelerator consisting of an interdigital H-type decelerator as well as a radio frequency quadrupole reduce...

The accuracy of optical clocks is unprecedented and the study of highly charged heavy ions in these instruments promises an exceptional robustness against external perturbations in combination with an exceptional sensitivity to fundamental, nuclear, and beyond-Standard-Model physics. To pursue this goal, we are setting up a unique spectroscopy platform at the HITRAP ion trapping facility and...

For photon energies from several tens of keV up to a few MeV, Compton polarimetry is an indispensable tool to gain insight into subtle details of fundamental radiative processes in atomic physics. Within the SPARC collaboration [1] several segmented semiconductor detectors have been developed that are well suited for application as efficient Compton polarimeters. For photon emission processes...

Study of electronic processes (ionization, excita-tion and capture) in ion-ion collisions is experimen-tally very challenging. So far, such collisions have been performed mainly in the low-energy regime (typically at center‐of‐mass energies ≾ a few 100 keV) where the charge transfer is by far the dominant process. Specific experimental conditions are required to perform absolute cross section...

The transverse electron target at the CRYRING has recently been commissioned successfully. It will allow investigating interactions between heavy ions and a collimated beam of monoenergetic electrons, including the emission of X-rays from radiative electron capture. For ions of low and medium nuclear charges, the X-ray transitions lie in the energy range of 1 – 50 keV. To determine the...

Electron-ion collision experiments in a
merged beams geometry (electron cooler) are
well established at ion storage rings. A complete
new range of experiments is possible if the geometry is changed to a crossed-beams setup in 90° angle between the electron and ion beams employing a dedicated free-electron target. The target
bridges the gap between low-collision-energy experiments in...

An active plasma lens is a device used to focus charged particle beams by means of a gas discharge initiated in a capillary aligned with the beam axis. The high current carried by the discharge plasma generates a strong azimuthal magnetic field, causing the charged particles traversing the plasma to experience a focusing Lorentz force.

Plasma lenses are particularly suited for...

Using the electron-ion crossed-beams technique, we have measured absolute cross sections for electron impact single ionization of Xe$^{12+}$ and Xe$^{13+}$ ions, and double ionization of Xe$^{12+}$, Xe$^{13+}$ and Xe$^{14+}$ ions. In addition we have performed corresponding calculations using a hybrid level-to-level and subconfiguration-average distorted wave approach. We find excellent...

Plasma lenses, created by gas discharges along the beam axis of charged particle beams, provide a compact and efficient approach to magnetic focusing. High currents initiated between ring electrodes generate azimuthal magnetic fields via Ampère's law, enabling symmetric focusing in both transverse planes. Compared to conventional solenoids and quadrupoles, plasma lenses achieve substantially...

As a first completed facility of the FAIR project, the heavy ion storage ring CRYRING@ESR is in operation since 2020 and is serving as experiment platform for the SPARC collaboration. The ring is optimized for low-energy storage and beam cooling, and with access to all ion species available from the GSI accelerator chain or from a local RFQ injector. This offers a unique access to study the...

Bunched relativistic ion beams with a narrow momentum distribution are essential for precision experiments at modern accelerator facilities. Laser cooling presents a promising approach to further reduce the relative momentum distribution of such ion beams.

This work presents the two high power UV laser systems, one pulsed and one cw, for laser cooling of relativistic bunched ion beams at...

The energy deposition of ions in water generates pressure waves, known as ionoacoustic signals. Ionoacoustic detection offers EMP-resilient diagnostics for (ultra-) short ion bunches over a broad dynamic range, enabling single-shot measurements of beam energy, dose, size, and position. We present recent developments of the I-BEAT detector as an online acoustic monitor for charged-particle...

The energy-resolved merged beams recombination rate coefficient α(E) for dielectronic recombination (DR) of O2+ has been measured on an absolute scale in the energy range from 0 to 45 eV. The experimental data comprises all ∆N=0 DR series associated with 2s → 2p core excitations and the lowest ∆N=1 DR series limits associated with 2p → 3s and 2p → 3d core excitations. In addition, we have...

In recent years, Metallic Magnetic Calorimeters (MMC) have emerged as excellent single photon detectors, exhibiting a broad spectral acceptance, ranging from a few to hundreds of keV, combined with a high energy resolution of $E/\Delta E (FWHM) \approx 6000$ [J. Geist. PhD thesis, 2020]. In combination with their fast rise time, they represent a superb tool for fundamental research in atomic...

Dielectronic recombination of N-like Ne was studied using a merged-
beams setup at CRYRING@ESR for collision energies from 0 to 25
eV. The measured energy-dependent recombination rate coefficient in-
cludes all ΔN=0 DR resonances from 2s to 2p core excitations was
compared with results from theoretical calculations. The ion beam
contained roughly equal fractions of ions in the...

As the upgrades of accelerator facilities are pushing the frontiers of high-intensity and high-energy particle beams, there is a demand for reliable beam extraction techniques into high-pressurized target areas with little impact on the beam properties. A promising technique that allows the extraction of such ion beams is the plasma window [1]. It is based on a cascaded arc discharge that...

S. Schippers, C. Brandau, S. Fuchs, M. Lestinsky, S.-X. Wang, C. Y. Zhang, N. R. Badnell, A. Borovik Jr., M. Fogle, V. Hannen, Z. Harman, P.-M. Hillenbrand, E. B. Menz, Y. Zhang, Z. Andelkovic, F. Herfurth, R. Heß, A. Kalinin, C. Kozhuharov, C. Krantz, S. Litvinov, B. Lorentz, U. Spillmann, M. Steck, G. Vorobyev, D. Banas, S. Fritzsche, E. Lindroth, X. Ma, A. Müller, R. Schuch, A....

The ARTEMIS experiment at the HITRAP facility situated at GSI, Darmstadt, focuses on precision measurements of electron magnetic moments in highly charged ions as a benchmark QED test in extreme fields. The experiment utilises a homogeneous magnetic field of 7 T with a harmonic electrostatic field which enables ion densities of up to 10e6 cm−3 to be stored for several days. The trap is equipped...

The heavy-ion synchrotron SIS100 is (at) the heart of the Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany. It is designed to accelerate intense beams of heavy highly charged ions up to relativistic velocities and to deliver them to unique physics experiments, such as those planned by the APPA/SPARC collaboration. In order to cool these extreme ion beams, "bunched beam...

Transition energy measurements in heavy, few-electron ions are unique tools to test bound-state quantum electrodynamics (QED) in extremely high Coulomb fields, where perturbative methods cannot be implemented. By accurately measuring the relative energies between $2p_{3/2} \to 2s_{1/2}$ transitions (of an energy of about 4.5 keV) in two-, three-, and four-electron uranium ions, we were able,...

The interaction of swift heavy ions (SHI) with organic matter is of high relevance for applications such as cancer therapy as well as biomaterials’ development based on SHI irradiation. Furthermore, the interaction of SHI with complex molecular systems such as biomolecules is interesting from a fundamental point of view in terms of the excitation mechanisms involved and how the energy...

Understanding how nanomaterials respond to radiation is essential for their reliable use in high-dose environments. At the nanoscale, size effects play a critical role, fundamentally altering energy dissipation mechanisms and influencing both intrinsic material properties and device performance. To deepen our understanding of ion–matter interactions in confined geometries, systematic studies...

Exploring the structural response and property transformations of materials under combined extreme conditions holds enormous importance across diverse multidisciplinary and fundamental research domains. The application of extreme pressures can induce novel phases and structures with distinctive properties. In this project, we explore the effects on exposing materials to radiation conditions...

State-of-the-art laser-driven plasma accelerators are entering the Hz repetition-rate regime, delivering ion beams with cut-off energies of multiple tens of MeV. For many applications, this creates an urgent need for a precise online dose monitor that can cope with the challenges of these sources and is capable of reconstructing the full dynamic range of the exponential dose...

Efficient DLA electron and proton acceleration from near-critical density is studied experimentally and in 3D PIC simulations. The 3D PIC simulations have shown that a smoothed density increase is favourable for DLA and leads to a higher effective temperature of accelerated electrons than in the case of a constant density plasma slab

Magnetic lens-based charged particle microscopy is a unique and powerful diagnostics technique capable of resolving ultra-fast processes on the ns-scale in dense matter with unprecedented micrometer spatial resolution. Recently, the PRIOR-II proton microscope facility has been designed, constructed and commissioned at the GSI Helmholtz Centre for Heavy Ion Research, pushing the technical...

We present experimental results from the HHT experimental area at GSI, demonstrating a robust method for single-shot focal spot characterization of the SIS18 heavy ion beam (238 U73+, 300 MeV/u).
The diagnostic setup utilized a Si (444) spherically bent crystal spectrometer coupled with a CCD camera to record the Cu K-alpha emission (8.048 keV) induced by the ion interaction with a thick...

Laser cooling, unlike established cooling methods such as electron cooling, promises to efficiently produce narrow longitudinal momentum distributions in relativistic bunched ion beams, even at large gamma factors. The concept was demonstrated (e.g. at the GSI in Darmstadt) using cw and pulsed laser systems separately, while the laser cooling facility in the upcoming heavy-ion synchrotron...

We report on the first laser excitation of the ground-state hyperfine transition in lithium-like
208-Bi80+. The experiment was performed at the ESR, in May 2025. Detection of the transition
was enabled through a new measurement scheme that combines laser excitation with dielectronic
recombination (DR). In this approach, the electron cooler is set to a voltage that leads to the DR
process...

M. Looshorn$^{*1,2}$, C. Brandau$^3$, M. Fogle$^4$, J. Glorius$^3$, E.-O. Hanu$^{3,5,6}$, V. Hannen$^7$,
P.-M. Hillenbrand$^3$, C. Krantz$^3$, M. Lestinsky$^3$, E.-B. Menz$^{3,8}$, R. Schuch$^9$, U. Spillmann$^3$,
K. Ueberholz$^7$, S.-X. Wang$^{1,2}$ and S. Schippers$^{1,2}$

$^1$I. Physikalisches Institut, Justus-Liebig-Universität Gießen, Giessen, 35392, Germany
$^2$Helmholtz...

Dielectronic recombination (DR) is widely recognized as the dominant electron–ion recombination mechanism in many astrophysical and laboratory plasmas, where it plays a crucial role in determining ionization balances and level populations over a broad temperature range. Moreover, DR experiments of highly charged ions (HCIs) at the storage rings have been developed as a precision spectroscopic...

The vacuum-ultraviolet to extreme-ultraviolet (VUV–EUV) variable-line-spacing (VLS) grating
spectrometer being installed at the gas-jet target of CRYRING is a new set-up for photon spectroscopy of
ion-atom collisions. The setup enables detection of fluorescence (roughly 4–40 eV) from collision induced
excitation, charge exchange, and multiple ionization of atoms and molecules by highly...