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Abstract

The phase-imaging ion cyclotron resonance technique (PI-ICR) has been implemented at TRIGA-Trap together with a newly built five-pole cylindrical trap. In PI-ICR the total phase of trapped ions is measured by projecting the ion motion onto a position-sensitive delay-line micro-channel plate detector. The systematic uncertainties have been investigated and first mass measurements on stable Pb isotopes have been performed with PI-ICR. The new technique offers higher mass-resolving power, allows checking for the presence of contaminant ion species, and it proved useful in tuning the harmonicity of the trapping potential as well as in aligning the trap symmetry axis with respect to the magnetic field axis by visualizing the radial ion motion. This is a non-scanning technique where every detected ion contributes equally, therefore it is more sensitive than the previously used time-of-flight ion-cyclotron-resonance (ToF-ICR) technique, which is based on the scanning of the sideband-frequency of trapped ions and recording their time of flight after ejection. It will enable us to carry out high-precision mass measurements in the actinide region with uncertainties on the ppb level.