α-decay-correlated mass measurement of 206,207g,m Ra using an α-TOF detector equipped multireflection time-of-flight mass spectrograph system

The atomic masses of the isotopes have been measured via decay-correlated mass spectroscopy using a multireflection time-of-flight mass spectrograph equipped with an -TOF detector. The Ra isotopes were produced as fusion-evaporation products in the reaction system and delivered by the gas-filled recoil ion separator GARIS-II at RIKEN. The -TOF detector provides for high-accuracy mass measurements by correlating time-of-flight signals with subsequent -decay events. The masses of and were directly measured using a multireflection time-of-flight mass spectrograph equipped with an -TOF detector. The mass excesses of and the excitation energy of were determined to be , and keV, respectively. The -decay branching ratio of , was directly determined from decay-correlated time-of-flight signals, and the reduced width of was calculated to be keV from the branching ratio. The spin-parity of was confirmed to be from decay correlated mass measurement results.