CVD Diamonds in the BaBar Radiation Monitoring System

To prevent excessive radiation damage to its Silicon Vertex Tracker, the BaBar experiment at SLAC uses a radiation monitoring and protection system that triggers a beam abort whenever radiation levels are anomalously high. The existing system, which employs large area Si PIN diodes as radiation sensors, has become increasingly difficult to operate due to radiation damage. We have studied CVD diamond sensors as a potential alternative for these silicon sensors. Two diamond sensors have been routinely used since their installation in the Vertex Tracker in August 2002. The experience with these sensors and a variety of tests in the laboratory have shown CVD diamonds to be a viable solution for dosimetry in high radiation environments. However, our studies have also revealed surprising side-effects.