Timing in fission fragment detection at high alpha-background

The ionisation multiplate fission chamber working together with a fast low-noise level preamplifier, is described. Fission fragments were registered with an efficiency of about 50% at a background of 108 α/s. The timing characteristics are illustrated by the time distributions of fission events measured at the μ− beam of 680 MeV synchrocyclotron, JINR Dubna.