Commissioning of the Rare-RI Ring at RIKEN RI Beam Factory

The Rare-RI Ring (R3) is an isochronous storage ring to measure masses of short-lived rare nuclei by using a TOF method*. The expected precision of the measured mass will be of the order of ppm. A commissioning run using a 78Kr beam was performed in June 2015 and basic performances of R3 were verified. We succeeded in injecting a particle, which was randomly produced from a DC beam from cyclotrons, into the R3 individually** with a fast kicker system***, and in extracting the particle from the R3 1 ms after the injection. We measured TOF of the 78Kr particles between the entrance and the exit of the R3 to check the isochronism. Through the first-order adjustment with trim-coils imbedded on the dipole magnets of the R3, the isochronism on the 10-ppm order was achieved for the momentum spread of ±0.2 %. Higher-order adjustment employed in future will lead us to the isochronism on the order of ppm. In addition, we confirmed that a resonance-type Schottky pick-up successfully acquired the revolution frequency information of one particle in a storage mode. In this conference, the technical aspects of the R3 and prospects from the results of the beam commissioning will be discussed.