NSLS-II beam loss control and monitoring system

Abstract

One of the most challenging issues for accelerator operations is why and where the beam is lost. This is a major concern for radiation protection at facilities with a large user base, since uncontrolled beam losses could potentially result in unwanted radiation exposures to occupied areas. For NSLS-II the tunnel radiation shield wall has increased attenuation over two lattice cells after the injection region, to shield for the possibility of higher injection losses. This raised the concern over exceeding radiation exposure limits in lesser shielded regions, if similar losses occur in those regions. To address this issue a beam loss control system was designed to limit most beam losses to the more heavily shielded (injection) region. A beam loss monitor system was also designed to verify the fraction of the beam lost in that region and thereby ensure lower levels of exposure around the rest of the ring. The design of these beam loss control and monitoring systems and the NSLS-II operational experience is presented.