Progress of beam commissioning and beam loss mitigation in the J-PARC linac after the Tohoku earthquake

Maruta, Tomofumi; Miura, Akihiko ; Sako, Hiroyuki   ; Tamura, Jun  ; Ikegami, Masanori*; Futatsukawa, Kenta*; Fang, Z.*; Miyao, Tomoaki*; Liu, Y.*

The Tohoku earthquake in March 2011 caused a significant damage to the J-PARC linac and forced us to shutdown the accelerator for nearly nine month. After significant effort for its restoration, we have resumed the beam operation of the J-PARC linac in December 2011. After the resumption of beam operation, we have been suffering from beam losses which were not observed before the earthquake. Tackling with the beam loss issues, we have been reached the same beam power for user operation as before the earthquake. In this paper, we present the experience in the beam start-up tuning after the earthquake with emphasis on the beam loss mitigation efforts.