Operating characteristics of argonne's 50 μs RF particle separator beam

An RF separated beam line, Beam 10, for the 12-ft bubble chamber has been constructed at Argonne's ZGS Complex. It utilizes two copper S-band RF deflecting structures, currently separated by a drift length of 31.25 m. The structures are excited from a central high-power RF modulator station, which can provide up to 10 MW of 50 1Ls pulsed RF power to each structure. The beam is instrumented with proportional wire chambers and scintillation counters. The first use of this beam was in taking 100,000 pictures in the 12-ft bubble chamber of 7.14 GeV/c protons where the rejected Π
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contamination was 7%. Currently, tuning studies to provide a separated K-beam at 6.52 GeV/c are taking place. Some pictures of interesting K- interactions in the 12-ft chamber are included. A unique feature of this beam is the use of a fast RF diode switch to turn off the low power RF drive and, consequently, stop the beam when a maximum number of tracks (typically about 10) have entered the chamber. This feature has resulted in an improvement of the picture taking rate of the chamber by 30% o for the 7.14 GeV/c proton run.