Precise mass measurement of nuclides

The mass of atomic nuclides reflects directly the sum effect of the strong, weak and electromagnetic interactions among the participating nucleons. A brief description of the importance, history and current status of nuclear mass measurements is given. With the recent commissioning of a cooler storage ring at the Heavy Ion Research Facility in Lanzhou, the masses of 63Ge, 65As, 67Se and 71Kr have been measured for the first time. The values have been compared with the theoretical predictions, and the implication of the 65As mass in the astrophysical rapid proton capture process has been addressed. Future research plans are presented. In the light mass region, precise mass measurements of the neutron-rich isotopes from Ne to Ca will be carried out, and the evolution of the N=20 and 28 shell closures studied while changing the neutron or proton numbers. In the proton-rich mass region, measurements will focus on the nuclei located in the path of the rapid proton capture process in stellar nucleosynthesis, and this can improve our understanding of explosive astrophysical phenomena, such as Type I X-ray bursts. In the medium-heavy neutron-rich mass region, systematic mass measurements will be performed, and the experimental data willserve as important input in the theoretical simulation of the rapid neutron capture process in the explosion of supernova.