Laser cooling of externally produced Mg ions in a Penning trap for sympathetic cooling of highly charged ions

Abstract

We have performed laser cooling of Mg + ions confined in a Penning trap. The externally produced ions were captured in flight, stored and laser cooled. Laser-induced fluorescence was observed perpendicular to the cooling laser axis. Optical detection down to the single ion level together with electronic detection of the ion oscillations inside the Penning trap have been used to acquire information on the ion storage time, ion number and ion temperature. Evidence for formation of ion crystals has been observed. These investigations are an important prerequisite for sympathetic cooling of simultaneously stored highly-charged ions and precision laser spectroscopy of forbidden transitions in these.

Rapid crystallization of externally produced ions in a Penning trap

“…The experiments were performed with the SpecTrap experiment [18,25] located at the HITRAP facility [26] at GSI and FAIR, Germany. The experimental setup ( Fig.…”

“…The experimental setup ( Fig. 1) has previously been described in detail [18]. Briefly, a cylindrical Penning trap is located in the homogeneous field of a superconducting magnet and is cooled to liquid-helium temperature.…”

“…It is a cylindrical open-endcap five-pole Penning trap [14] (one segmented ring and two compensation electrodes between endcap electrodes E1 and E2) with additional capture electrodes C1 and C2. The latter are used for dynamic capture [17,18] of externally produced ions by creating a potential well after incoming ions have entered the trap. The ring electrode located in the optical plane is split into four segments for radial electronic excitation and detection, with one hole of 4.8 mm diameter in each segment for optical access.…”

“…Here, we discuss laser cooling of singly charged magnesium ions in a Penning trap [14][15][16], following their dynamic capture [17,18] from an external source. In such situations, they commonly have high initial energies unsuitable for efficient laser cooling.…”

Half-open Penning trap with efficient light collection for precision laser spectroscopy of highly charged ions

“…In this design, the light collection efficiency is limited by the required ratio of diameter to length of the arrangement. Radial trap openings as used in experiments like [5,6,7] circumvent this limitation, but are likely to be unsuitable when high precision of the confining fields comparable to experiments like [8,9,10,11] is required. Also, they necessitate either complicated light collection schemes [5] or radial access to the trap [6,7].…”