Electron cooling tames highly charged ions in Penning trap for first time

Electron cooling tames highly charged ions in Penning trap for first time Sadie Harley Scientific Editor Robert Egan Senior Editor Researchers at Technical University of Darmstadt and the GSI Helmholtz Center for Heavy Ion Research have succeeded for the first time in decelerating highly charged ions from the GSI accelerator to low energies and subsequently storing them in a Penning trap. They were also successful in performing the first electron cooling of highly charged ions in such a trap. The results have been published in Physical Review X (PRX). Highly charged ions are typically produced at high energies and travel at high velocities. However, many experiments in atomic, nuclear and fundamental physics require these ions to be strongly decelerated, captured and cooled. The HITRAP facility at GSI was specifically developed for this purpose and will provide unique opportunities for experiments with slow highly charged ions. In the work now published, carried out in close collaboration with GSI's Decelerator Division, researchers succeeded for the first time in decelerating and trapping fully ionized argon ions from the accelerator system through several stages. "In the experiment we conducted, we used argon ions from which we had stripped away all electrons, leaving only the bare atomic nuclei," reports Dr. Simon Rausch, lead author of the publication, who earned his Ph.D. in Professor Wilfried Nörtershäuser's research group at the Department of Physics at TU Darmstadt. From near light speed to trapping "The production took place at about 30% of the speed of light, and before we could trap the ions, we first had to reduce their kinetic energy by a factor of about 10,000." This was achieved in the decelerator structure of the HITRAP facility. The ions were then stored in the HITRAP Cooling Trap for several seconds. "This marked the first time the entire path of accelerator-produced highly charged ions—all the way to their storage in a Penning trap—was demonstrated," Rausch says. Cooling opens the way for precision work The researchers also achieved the first observation of electron cooling of highly charged ions in a Penning trap. This technique reduces the ions' kinetic energy and constitutes a key prerequisite for future high-precision experiments. The newly published results establish the technological foundations for a broad range of experiments at HITRAP. Their significance was already demonstrated in the first user experiment at the facility, where slow highly charged gold ions were used for materials science studies. The milestones described in PRX provide the basis for a unique research platform for precision studies with heavy highly charged ions. Publication details S. Rausch et al, Deceleration of Accelerator-Produced and In-Trap Electron Cooling of Highly Charged Ions, Physical Review X (2026). DOI: 10.1103/961c-j3p5 Journal information: Physical Review X Provided by Technische Universitat Darmstadt