Investigation of solenoid fringe field based on change in 3-Gev proton beam orbit and the orbit correction

Yamaguchi, Yuji   ; Meigo, Shinichiro   ; Yamazaki, Takayuki*

Fringe field of a secondary-particle capture solenoid magnet with three coils has been experimentally investigated placed at muon science facility in materials and life science experimental facility (MLF), J-PARC. To clarify relationship between the fringe field and excitation current of each coil and interference of fields by the coils, proton beam position changes in vertical direction were measured for 125(= 5) combinations of excitation currents using a multi-wire profile monitor located in front of the final target of MLF. The measured position changes show that the field by the most upstream coil is non-linear with its current while the fields by other coils are linear and that the field can be enhanced by excitation of multiple coils. The non-linearity of the filed by the most upstream coil has been introduced to the proton beam orbit correction, which has been demonstrated.