Performance of the bump system for the painting injection at J-PARC

Takayanagi, Tomohiro   ; Ueno, Tomoaki; Togashi, Tomohito; Harada, Hiroyuki*; Saha, P. K.   ; Hotchi, Hideaki  ; Kinsho, Michikazu  ; Kamiya, Junichiro   ; Watanabe, Masao  ; Yoshimoto, Masahiro  ; Irie, Yoshiro*; Sato, Kenichiro*

The shift bump-magnets, which give a constant bump field in a horizontal plane during injection, comprise four magnets connected in series. However, the total integrated magnetic field over the four magnets is not zero because of the magnetic field interferences with the neighboring quadrupole magnets. So the gap of each magnet was adjusted by inserting thin insulators into the splitting plane of the side yoke so that the field integration becomes zero. The closed orbit distortion due to the field imbalances was then confirmed to be less than 1 mm. Another four paint bump-magnets are connected to their own power supplies, separately. The excitation of each magnet is calibrated by using the beam so that the created bump orbit satisfies the position and inclination at the injection point, and there are no orbit distortions outside the injection area.