Longitudinal beam profile measurement at J-PARC separated drift tube linac

Maruta, Tomofumi; Miura, Akihiko ; Sako, Hiroyuki   ; Wei, G.; Ikegami, Masanori*

In J-PARC linac, we have been experiencing beam losses at the beam transport line after the linac exit. There has been an argument that the longitudinal loss could be a cause of the beam loss, which motivated us to conduct an experimental investigation on the margin between the longitudinal acceptance of the linac and the actual beam distribution. In the experiment, we have introduced a "tank level scan" to measure the margin in the energy direction in addition to the conventional phase scan which has been employed to measure the margin for the phase direction. The measurement scheme and experimental results are presented in this paper.