New Beam Loss Monitor for 12 GeV Upgrade
J.Yan*, K.L.Mahoney (JLAB)
This paper describes a new VME based machine protection Beam Loss Monitor(BLM) signal processing board designed at Jefferson Lab which features high sensitivity, high resolution, and low cost per channel. Photomultiplier based BLMs are used to detect bremsstrahlung from low level beam loss during tune-up and beam operations and to provide a machine protection trip before the beam can damage accelerator components. Typically, the two functions are incompatible as the display of instantaneous low level loss requires a fast low noise, wide dynamic range signal processor while machine protection requires some form of high level integrating signal processor. The new 8-channel BLM card has linear, logarithmic, and integrating amplifiers that simultaneously provide the optimal signal processing for each application. Amplified signals are digitized and then further processed through a FPGA. Combining both the diagnostic and machine protection functions in each channel allows the operator to tune-up and monitor beam operations. Other features include extensive built-in-self-test, fast shutdown interface(FSD), and 16-Mbit buffers for beam loss transient play-back.
Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177