Start detector based on microchannel plates

A start detector intended for investigation of the products of interaction of two compound nuclei by the time-of-flight method is described. The detector uses secondary emission of electrons registered by the microchannel plates (MCP). Secondary electrons knocked out by the interaction products from a thin foil are accelerated by the lattice up to the approiimately 1 keV energy, and then they are turned on 180 deg by the magnetic field. The MCPs are made of glass with impurity of lead oxxde and have the form of a disk of the 30-40 mm diameter and 1 mm thickness, having 10 mm open channels. A secondary electron gets into the MCP channel and excites electron multiplication on the microchannel walls covered with special material with a great yield of secondary electrons. To produce a secondary electron avalanche on the internal MCP surface the approximately 1 keV voltage is applied to the MCP. The MCP gain is 104. To increase the gain an assembly of two MCPs is used. The assembly gain is 107 - 108. The experimentally measured time resolution of the ''start detector - semiconductor detector'' system is 1 ns