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MPINP:
Präzisionsexperimente - Abteilung Blaum
Abstract:
The ability to transfer the temperature of laser cooled ions to species without a suitable optical cooling transition is of vital interest for the next generation of experiments with trapped ions. For example, our experiment (BASE-Mainz) performs high-precision Penning-trap measurements of the proton magnetic moment. The currently most precise measurement is limited by the non-zero particle temperature of about 1 K. Recently, we have demonstrated the first sympathetic cooling of a single proton with laser cooled beryllium ions. Here, both species are located in macroscopically separated traps and the coupling is mediated by image currents, which are enhanced via a superconducting RLC circuit. Due to the spatial separation between the target ion and the laser-coolable species, this cooling method can be applied not only to a single proton, but to any charged particle, including exotic particles such as antiprotons or highly-charged ions. In the course of this thesis, a particle temperature of (160 ± 30)mK was reproducibly achieved for such a sympathetically cooled proton. This constitutes an improvement by a factor of 16 compared to the previous record of (2.6±2.5)K and is a factor of 55 below the environment temperature. This accomplishment was enabled by two major advancements:
First, numerical simulations of the coupled Penning-trap system were developed and carried out, which significantly progressed the understanding of the coupling and cooling mechanism.
Second, a new experimental apparatus was commissioned, which comprises among other upgrades a dedicated temperature measurement trap. In addition, the simulations were employed to establish future cooling schemes that reach temperatures of 10mK and possibly below.
