Noise Reduction on the LEP bunch current measurement system

The lifetimes of coasting beams in LEP are computed from the difference of the bunch currents measured during a time interval of a few seconds. The quality of these measurements is presently limited by the noise figure of the bunch to bunch aquisition system. This paper describes comparative studies on the aquisition system in order to improve the noise figure by one order of magnitude. For this purpose three different principles, i.e. integrating measurements, peak hold circuits with internal timing (autotrigger) or peak hold circuits with external timing were studied. This paper describes the results of these studies.