Atomic masses of intermediate-mass neutron-deficient nuclei with relative uncertainty down to 35-ppb via multireflection time-of-flight mass spectrograph

Abstract High-precision mass measurements of Cu 63 , Zn 64 − 66 , Ga 65 , Ge 65 − 67 , As 67 , Br 78 , 81 , Rb 80 , and Sr 79 were performed utilizing a multireflection time-of-flight mass spectrograph combined with the gas-filled recoil ion separator GARIS-II. In the case of Ga 65 , a mass uncertainty of 2.1 keV, corresponding to a relative precision of δm / m  = 3.5 × 10 −8 , was obtained and the mass value is in excellent agreement with the 2016 Atomic Mass Evaluation. For Ge 67 and Br 81 , where masses were previously deduced through indirect measurements, discrepancies with literature values were found. The feasibility of using this device for mass measurements of more neutron-deficient nuclei, which have significant impact on the rp -process pathway, is discussed.