Rostock 2019 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 9: Precision Spectroscopy of atoms and ions III (joint session A/Q)
A 9.5: Vortrag
Montag, 11. März 2019, 17:30–17:45, S HS 2 Physik
Resistive cooling of highly charged ions in a Penning trap to a fluidlike state — Mohammad Sadegh Ebrahimi1, •Zhexi Guo1,2,3, Manuel Vogel1, Marco Wiesel1,4, Wolfgang Quint1,3, and Gerhard Birkl4 — 1GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt, Germany — 2Max-Planck-Institut für Kernphysik, 69117 Heidelberg, Germany — 3Physikalisches Institut, Universität Heidelberg, 69120 Heidelberg, Germany — 4Institut für Angewandte Physik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
Resistive cooling of large ensembles of highly charged ions such as Ar13+ was studied in detail in a cryogenic Penning trap. In contrast to earlier measurements by Vogel et al. [Phys. Rev. A 90, 043412 (2014)], purely exponential cooling behaviour was observed when conditions were chosen to allow collisional thermalisation of the ions. The results obtained under such conditions indicate that resistive cooling time constants and final temperatures are independent of the initial ion energy and that the cooling time constant of a thermalised ion ensemble is identical to the single-ion cooling time constant. For sufficiently high ion number densities, measurements showed discontinuities in the spectra of motional resonances which indicate a transition of the ion ensemble to a fluidlike state when cooled to temperatures below approximately 14 K. With the final ion temperature at 7.5 K, ions of the highest charge states are expected to form ion crystals solely through resistive cooling without the need for laser cooling.