Octupolar excitation of ions stored in a Penning trap mass spectrometer—A study performed at SHIPTRAP

The response of ions stored in a Penning trap to excitation by an octupolar radio frequency field was investigated using the time-of-flight ion-cyclotron resonance method at the SHIPTRAP Penning trap mass spectrometer at GSI. The mass resolving power can be improved at least by an order of magnitude and the accuracy more than doubled as compared to the conventional quadrupolar excitation. It has been shown that the octupolar excitation can be used to determine the mean magnetron radius of the stored ions as well as the radius of their initial spatial distribution in the Penning trap. Along with the experimental investigation, the octupolar excitation in a cylindrical Penning trap was simulated. Excellent agreement between experiment and simulation is observed.