Sprecher
Beschreibung
C. Brandau$^{1,2}$, A. Borovik Jr.$^{1}$, B. M. Döhring$^{1,3}$, D. Banas$^{4}$, J. Glorius$^{2}$, A. Gumberidze$^{2}$, E. O. Hanu$^{2,5,6}$, P.-M. Hillenbrand$^{1,2}$, P. Jagodzinski$^{4,7}$, A. Kalinin$^{2}$, A. Krishnan$^{2,8}$, M. Lestinsky$^{2}$, M. Looshorn$^{1,3}$, E. B. Menz$^{2}$, U. Spillmann$^{2}$, K. Szary$^{4}$, R. Tyagi$^{9}$, J. Viehmann$^{9}$, S.-X. Wang$^{1,3}$, S. Schippers$^{1,3}$
$^{1}$I. Physikalisches Institut, Justus-Liebig-Universität Gießen, Germany
$^{2}$GSI-Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany
$^{3}$Helmholtz Forschungsakademie Hessen für FAIR (HFHF), Germany
$^{4}$Institute of Physics, Jan Kochanowski University, Kielce, Poland
$^{5}$Helmholtz-Institut Jena, Germany
$^{6}$Institut für Kernphysik, Goethe-Universität Frankfurt, Germany
$^{7}$Central Office of Measures, Warszawa, Poland.
$^{8}$Institut für Angewandte Physics, Technische Universität Darmstadt, Germany
$^{9}$Institut für Physik, Universität Kassel, Germany
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 electron coolers and those employing quasi-free electrons of gas-jet targets. Compared to the latter, the absence of a target nucleus enables unambiguous studies of processes, which are otherwise masked by competing reactions with the target nucleus. As compared to an electron cooler, the interaction region of a transverse target is spatially well localized. This facilitates X-ray and electron spectroscopy with relatively large solid angles. Over the last years, a specially tailored electron-target for heavy-ion storage rings was developed and built at the University of Giessen in cooperation with GSI. Its scientific prospects have been outlined in the CRYRING@ESR Physics Book [1]. The project benefits from decades-long experience of single-pass electron-ion-collision experiments [2–4]. The target is equipped with a versatile electron gun that is optimized for an operation in storage rings. The electron gun can be fully retracted from the storage ring to a position behind a gate valve. One of the specific design criteria was a rather large opening for the ion beam in order to accommodate ion injection into the storage ring on different orbits. First electron-ion beam experiments showed that in total only up to 20% of ions are lost due to the electron target which is a great success. The electron target creates a ribbon-shaped high-intensity electron beam with energies up to 12.5 keV (lab system). The multi-electrode assembly offers a decoupling of electron energy and electron density, which is beneficial for the ultrahigh vacuum conditions in the ring. It also offers a quasi-constant electron density over large energy ranges. We report on the latest achievements during the commissioning beamtimes of the electron target at the CRYRING@ESR. The evaluation of the performance and operation behaviour is ongoing.
[1] M. Lestinsky et al., Eur. Phys. J Spec. Top. 225, 797 (2016).
[2] B. Ebinger et al., Nucl. Instrum. Methods B 408, 317 (2017).
[3] F. Jin et al., Eur. Phys. J. D 78, 68 (2024).
[4] B. M. Döhring et al., Atoms 13, 14 (2025)
