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 aquistion system. This paper decribes comparative studies on the aquistion 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. The paper describes the results of these studies.