The 3-GeV rapid cycling synchrotron (RCS) of the Japan Proton Accelerator Research Complex was commissioned in October 2007. Via the initial beam tuning and a series of underlying beam studies with low-intensity beams, since December 2009, we have intermittently been performing beam tuning experiments with higher-intensity beams including the injection painting technique. By optimizing the injection painting parameters, we have successfully achieved a 420 kW-equivalent output intensity at a low-level intensity loss of less than 1%. Also the corresponding numerical simulation well reproduced the observed painting parameter dependence on the beam loss, and captured a characteristic behavior of the high-intensity beam in the injection painting process. In this paper, we present the experimental results obtained in the course of the RCS beam power ramp-up, especially on the beam loss reduction achieved by employing the injection painting, together with the numerical simulation results.

• Received 14 July 2011

DOI:https://doi.org/10.1103/PhysRevSTAB.15.040402

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Published by the American Physical Society