On-line commissioning of SHIPTRAP

The on-line commissioning of the Penning-trap mass spectrometer SHIPTRAP was successfully completed with a mass measurement of holmium and erbium radionuclides produced at SHIP. A large fraction of contaminant ions created in the stopping cell was identified to originate from the buffer-gas supply system. Using a liquid nitrogen cold trap they were reduced to a tolerable amount and mass measurements of Er147, Er148, and Ho147 with relative uncertainties of about 1×10−61×10−6 were performed.