https://doi.org/10.1140/epjs/s11734-026-02357-0
Regular Article
The CRYRING@ESR electron cooler as internal target for atomic physics experiments
1
GSI Helmholtz Centre for Heavy-Ion Research, 64291, Darmstadt, Germany
2
Johann Wolfgang Goethe-Universität Frankfurt, 60323, Frankfurt am Main, Germany
3
Helmholtz-Institut Jena, 07743, Jena, Germany
4
I. Physikalisches Institut, Justus-Liebig-Universität Gießen, 35392, Giessen, Germany
5
Helmholtz Forschungsakademie Hessen für FAIR, GSI Helmholtz Centre for Heavy-Ion Research, 64291, Darmstadt, Germany
6
Department of Physics, National Technical University of Athens, 15780, Zografou, Greece
7
European Spallation Source, 221 00, Lund, Sweden
8
Institut für Kernphysik, University of Münster, 48149, Münster, Germany
9
Institute for Nuclear Physics, University of Cologne, 50937, Cologne, Germany
10
Department of Physics, University of Stockholm, 106 91, Stockholm, Sweden
11
Karlsruhe Institute of Technology, 76344, Eggenstein-Leopoldshafen, Germany
a
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Received:
26
February
2026
Accepted:
24
April
2026
Published online:
13
May
2026
Abstract
We present developments at the electron cooler of the CRYRING@ESR storage ring aimed at improving its performance as internal target in low-energy electron–ion collision experiments. We describe recent modifications of the high-voltage and vacuum systems which lead to improved electron energy control and lower background count rates during such measurements. In a benchmark experiment on dielectronic recombination of F
, we demonstrate that a spectroscopic resolution equivalent to transverse and longitudinal thermal electron energy spreads of 
1 meV and 45 µeV, respectively, can be achieved under optimum conditions. This surpasses system performance observed previously in similar experiments.
Present address: Karlsruhe Institute of Technology, 76344, Eggenstein-Leopoldshafen, Germany
© The Author(s) 2026
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