The JILA Penning trap mass spectrometer

A Penning-ion trap mass spectrometer which is designed to make sub ppb mass measurements on ions is described. The spectrometer incorporates an external ion source for the injection of ions to be 'weighed' into the trap. Novel features include a nonmagnetic alloy from which the trap electrodes are machined, as well as an ion detection system based on a superconducting inductor and a very low-noise amplifier incorporating a gallium-arsenide field-effect transistor (GaAs FET). Also discussed is a technique to increase the axial resistive damping constant for trapped ions using a regenerative detection circuit