Interlock of beam loss at low-energy part of J-PARC linac

The output beam power of the J-PARC linac has been improved by increasing the acceleration energy and peak beam current. The beam loss is getting serious along with increasing output beam power; however, the beam loss in the front-end region is difficult to detect because of the low energy of the radioactive emission. An interlock system using the beam current monitors has been developed to prevent significant material activation. In this system, an electrical circuit measures the beam transmission between the two beam current monitors. This study describes the design and performance of this electrical circuit and introduces the system configuration. (author)