A Penning trap for g-factor measurements in highly charged ions by laser-microwave double-resonance spectroscopy

Abstract

Precise determination of bound-electron g-factors in heavy highly-charged ions (e.g. Bi 82+ , U 91+ ) provides a stringent test of bound-state QED in extreme fields. With a laser-microwave double-resonance technique we will probe the microwave transitions between the Zeeman sub-levels of the hyperfine structure in highly charged ions. From this the bound electron g-factor g J can be determined. We present the experimental progress of this novel method to measure the g-factor of the bound electron in highly charged ions.

Could the electron’s orbital g-factor be anomalous?

“…For example, to determine the correction δs of electrons bound in atomic systems, Sturm, Werth and Blaum [13], were able to measure, using microwave spectroscopy, the g J values in the l=0 states of highly charged ions to an accuracy of about 1.1×10 −9 ; however, experiments have reached a level of precision where effects depending on the size of the trap limit further progress, although high resolution microwave/optical spectroscopy measurements that can be performed simultaneously on ions and atoms, could extend the precision. Brantjes et al [14] have recently described a new technique called the laser-microwave double resonance, with which g J values of bound systems may be determined to an accuracy in the range of 1×10 −9 . Measurements could (in principle) be made on l ≠ 0 states of ions in order to determine the influence of a possible anomaly on the measured g J .…”

"Experiments with heavy, highly charged ions - Status of the HITRAP project

“…The superconducting magnet for the g-factor trap has been installed and the trap design is finished. A number of electronic components like the detection circuit have been tested offline [17]. The spectroscopy trap will contain a small electron source to produce in trap test ions as for instance argon that is fed by a purpose designed cryogenic gas valve [18].…”