Floor deformation and vibration measurements of the J-PARC Linac

Morishita, Takatoshi  

The displacement of the accelerator components induces the beam losses so that the precise alignment is important for the stable beam operation of the high-intensity hadron accelerates. The J-PARC linac has finalized its precise alignment at the end of summer 2006. Since then, the deformation of the accelerator tunnel was small enough to maintain the alignment accuracy for five years without re-alignment. However, the long-term stability of the floor height became worth after that earthquake in March 11th, 2011. Since then, accelerator components in the linac are re-aligned every few years. During the precise survey, sometimes the measured data has significant fluctuation, which is considered due to the vibration of the tunnel floor. Then, the floor vibration was measured using the seismometer and the vibration meters. The long-term deformation of the accelerator tunnel and the property of the floor vibration are described with the relation between the environmental factors.