Signal response of the beam loss monitor as a function of the lost beam energy

Yamamoto, Kazami   

The 3 GeV rapid cycling synchrotron of the J-PARC accelerates a proton beam up to 3 GeV and delivers it to the main ring and the material and life science facility. The main magnets (dipole and quadrupole magnets) of the synchrotron have large aperture, and thickness of yoke is larger than 200 mm. Considering the stopping power of a proton, a shielding effect of the magnets for beam loss monitor strongly depends on the lost beam energy. When the beam loss occurs during injection, the lost proton cannot penetrate the magnet yoke. But when the beam loss occurs after acceleration, lost beam easily pass the magnet. Therefore the signal response of the beam loss monitor is changed by the lost energy. We estimated the signal dependence on the lost energy by the simulation. The results indicated that the response strongly depends on the location of the lost point and lost energy. It is proportional to the lost power except the condition that the magnets become the radiation shielding.