Progress on direct mass measurements of exotic nuclei with the FRS-ESR facilities at GSI

Heavy ion storage rings operated in an isochronous mode and/or equipped with the phase-shape cooling devices can be used for high-precision, high-sensitivity and high-efficiency mass measurements of stored nuclei. This has been achieved at GSI Darmstadt, where two complementary methods, Schottky Mass Spectrometry (SMS) and Isochronous Mass Spectrometry (IMS) were developed based on the combination of the fragment separator (FRS) and the storage ring (ESR). So far, the storage ring spectrometry has been successfully used in measuring about 300 unknown nuclear masses. In this contribution, I will discuss the progress on direct mass experiments of stored exotic nuclei, with emphasis on the first extension of the IMS in short-lived nuclear isomeric investigation, and the five new isotopes (²³⁶Ac, ²²⁴At, ²²¹Po, ²²²Po, and ²¹³Tl) discovered with the SMS. Preliminary results from a pilot study on the application of a new Resonant Schottky pick-up for mass and lifetime measurements of nuclei are also reported.