p¯-beam monitoring system for CP LEAR

A monitoring system has been developed for the antiproton beam used in experiments on the CP violating decays of K⁰ and anti-K⁰ by the CP LEAR collaboration at LEAR, CERN. The beam position is measured by means of two small MWPCs. In each MWPC two anode wires, 8 mm apart, provide gas amplification. The position of the beam is obtained from induced current signals on cathode strips. A small scintillator (diameter 7 mm, thickness 1 mm) gives a signal to be included in the trigger. The scintillation light is guided to a PM outside the solenoid by means of 5-m-long PMMA (plexiglass) fibers. The system is mounted on the beam pipe, close to the center of the experimental setup. The beam position resolution is better than 0.5 mm, and the time resolution is ≈100 ps