Design of beam optics in the proton beam transport line from synchrotron to spallation neutron target

Meigo, Shinichiro   ; Noda, Fumiaki*; Fujimori, Hiroshi*; Ikeda, Yujiro

In J-PARC project, spallation target is irradiated by 3 GeV proton beam of 1 MW. Due to hands on maintenance for the proton beam lines, loss of proton beam is limited less than 1 W/m. Since it is difficult to predict the phase space distribution of the proton beam, we decided that the beam line have to be larger acceptance for 324 mrad, which is determined by the collimator located in the synchrotron. Distortion of proton beam is caused by the by the instability of angle at the extraction of 3-GeV synchrotron, miss alignment of the magnet, and un-uniformity of the magnet field. In this study, the distortion is calculated. In order to fit the conditions, the stability of extraction angles should be kept smaller than 0.2 mrad. As for the magnetic field, it is found that the uniformity should be kept better 5x10 and 2x10 for bending and quadruple magnets, respectively. It is also found the error of alignments should be limited smaller than 1.0 mm and 1.0 mrad.