Beam Dynamics and Commissioning of the J-PARC Linac

At the first stage of J‐PARC (Japan Proton Accelerator Research Complex), the linac will accelerate a H− beam to 181 MeV with a peak current of 30mA. A normalized transverse emittance of less than 4πmm⋅mrad and a momentum spread of less than ±0.1% are required at the injection point of the the rapid cycling synchrotron (RCS) following the linac. In order to find out operating points satisfying the above requirements and develop commissioning strategies, intense simulation studies of the linac have been performed. The beam commissioning of the drift‐tube linac tank‐1 (DTL1) has been performed at KEK. Transverse emittances at the DTL1 exit, phase scan property of the DTL1, and so on have been measured to confirm the validity of the simulations and commissioning strategies.