Estimation of secondary electron effect in the J-PARC Rapid cycling synchrotron after first study

Yamamoto, Kazami   ; Kamiya, Junichiro   ; Ogiwara, Norio; Kinsho, Michikazu  ; Hayashi, Naoki  ; Saeki, Riuji; Sato, Kenichiro*; Toyama, Takeshi*

The Japan Proton Accelerator Research Complex (J-PARC) project is a joint project of Japan Atomic Energy Agency (JAEA) and High Energy Accelerator Research Organization (KEK). The accelerator complex of J-PARC consists of a 181 MeV Linac, a 3 GeV Rapid-Cycling Synchrotron (RCS) and a 50 GeV Main Ring (MR). The RCS ring is designed to support 1 MW of beam and to deliver a 3 GeV pulsed proton beam to the spallation neutron target and the MR at a repetition rate of 25 Hz. Since the RCS finally accelerates very high intensity beam, the secondary electron cloud may affect the accelerator performance. The electron cloud effect in RCS was evaluated by simulations, but the secondary electron emission yield (SEY) of the chamber surface and beam loss point, lost proton number were assumed. In this Study we measured the SEY from the samples which was dealt with similar process of an actual chamber surface. We estimate the practical influence of the secondary electron cloud during beam operation.