Experience with photomultiplier base beam loss monitors (PMBLM) at the Low Energy Demonstration Accelerator (LEDA)

LEDA is presently configured for investigating space charge induce halo formation . A total of seven PMBLM units are placed along the transport between the RFQ and the beam dump. Each PMBLM consist of a 5 cm diameter by 1.25 cm thick CsI(Tl) scintillation crystals attached to 5 cm diameter 10 or 11 stage photomultiplier (PM). The voltages to the PM's are adjustable thus giving the system a wide dynamic range. Approximately 200 ft. of cable carries the output current to a transimpedance amplifier outside the high radiation area. The system bandwidth is about 170 kHz thus allowing the observation of 1 /spl mu/s rise time constant signals. After further processing the PMBLM signals are presented to A/D's in a VXI crate for data acquisition by the EPICS control system. Beam loss fast protect signals are also generated. This paper will discuss the motivation, design and operational experience with this PMBLM system.