A Coaxial Cable Beam Loss Monitor Ion Chamber System for High Power Multi-bunch Beams

Gas filled coaxial cable beam loss monitors are a proven diagnostic in short pulse linacs and transport lines. At the SLAC linear collider (SLC), where the bunch length ({sigma}{sub Z}) is {approx}1 mm, monitor cables with lengths ranging from 1m to 3 km are used to locate beam losses of 5 x 10{sup 8} particles (1.5% of the nominal intensity) with a resolution of {+-}1 m. The monitor is effective because of the simplicity of its installation and signal interpretation. Future linear colliders (LC) will use beams made up of trains of many closely spaced bunches and will therefore require more careful signal processing in order to locate losses. Typical collider operation will involve the use of pilot pulses, made up of only one bunch, to test subsystem performance prior to full power operation. A simple signal processor will be able to locate losses by comparing the evolution of the loss monitor signal as the number of bunches is increased. The monitor must have 10 times greater sensitivity than the SLC monitors in order to provide a prediction of the expected beam loss at full power using only the signal from the pilot pulse. This paper describes the proposed linearmore » collider loss monitor system.« less