Present design and calculation for the injection-dump line of the RCS at J-PARC

Saha, P. K.   ; Noda, Fumiaki*; Irie, Yoshiro; Hotchi, Hideaki  ; Takayanagi, Tomohiro   ; Hayashi, Naoki  ; Machida, Shinji*; Sakai, Izumi*

The RCS(rapid cycling synchrotron) of J-PARC(Japan proton accelerator research complex) acts as an injector to the main ring as well as a high-power beam for the spallation neutron source at a repetition rate of 25 Hz, where at present the injection and the extraction beam energy are chosen to be 0.181 GeV and 3.0 GeV, respectively. The present work concerns on the present design and calculations for the injection-dump line of the RCS, which includes, (1) an accurate aperture list of all elements taking into account a wide range of the betatron tune, effect of changing injection modes, multiple trajectories of different particles after the charge-exchange foil(like H0 from the H- and H- beam itself)and (2) an accurate estimation of the uncontrolled beam losses especially from the H0-excited states, multiple coulomb scattering at the charge-exchange foil and also the lorentz stripping loss at the septum magnets so as to optimize them concerning mainly the radiation issues as well as for the hands-on maintenance.