Ultra high speed microchannel photomultiplier

Investigations to improve the response speed of photomultipliers as applied to the study, of very short light phenomena, results in a new tube design. The classic array of dynodes is replaced by a microchannel wafer inner diameter of each channel (≃ 40 µm). The small thickness (≃ 2 mm) of this electron multiplier leads to an important reduction of the electron transit time and, consequently, of the time spread. Electronic coupling between the photocathode and the microchannel plate is obtained by using proximity focussing. The distance between these two electrodes is about one millimeter. The applied electric TM field, (∼5,000 V.cm^-1), makes the electron flight time spread in this stage negligible ( s) compared to the transit time spread in the multiplier ( s).