First mass measurement of short-lived nuclides at HIRFL-CSR

Recent commissioning of the HIRFL-CSR has demonstrated its ability to perform direct mass meas-urement for short-lived nuclides. Projectile fragments produced by the ⁷⁸Kr ions at 481.88 MeV/u were separated with the new radioactive beam line in Lanzhou (RIBLL2), and injected into and stored in the experimental storage ring (CSRe). By operating the CSRe as an isochronous mass spectrometry, a typical mass resolution around 2.0×10^-5 has been achieved. The masses for ⁶³Ge, ⁶⁵As and ⁶⁷Se were measured for the first time. The measured masses are compared with theoretical predictions and the location of the proton drip-line for As isotopes is discussed. The implication of the ⁶⁵As mass in the astrophysical rapid proton capture process has also been addressed.