Abstract: An electron multiplier of the perforated sheet type includes two successive sheets constituting a dynode which has several multiplier channels in common. For controlling the gain of a given channel (A), a control electrode (30) is provided in the form of a sheet inserted between the sheets (14, 15) of a dynode (Dn) which has a grating window (33) controlling the gain of the channel (A) in question, and one (or several) aperture(s) (34) in accordance with the number of remaining channels. Another channel (B) is controlled by another electrode (31) inserted between the sheets (16, 17) of another dynode (D.sub.n+1). Also disclosed is a multi-channel photomultiplier tube which includes such an electron multiplier.

Abstract: A photomultiplier tube comprising a photocathode (10), focusing electrodes (12, 12') and a fast multiplier structure (20) having a large input surface relative to the photocathode and comprising at least one input dynode (21). According to the invention, said photomultiplier tube comprises, between the photocathode (10) and said focusing multiplier structure (20), a first multiplier stage (30) comprising, in succession and viewed from the assembly consisting of the photocathode (10) and the focusing electrodes (12, 12'), a grid (31), a first multiplier dynode (32) of the apertured-plate type, and an extracting grid (33) having the same pattern as said first multiplier dynode (32), the output of the extracting grid (33) being coupled to said input dynode (21) of the multiplier pattern by means of a focusing electrode (40).

Abstract: Photomultiplier tube 10 segmented into a plurality of elementary photomultipliers 11 comprising a photocathode 12 and a multiplier 13 of the type using sheets partitioned into a plurality of elementary multipliers 14. According to the invention the input space of the tube 10 located between the photocathode 12 and the multiplier 13 is partitioned into elementary input spaces 15 associated with the elementary photomultipliers and defining a plurality of elementary photocathodes 16, with each elementary input space 15 having a focussing electrode which causes the photo-electrons emitted by the associated elementary photocathode 16 to converge on the corresponding elementary multiplier 14.

Abstract: An electron multiplier structure comprising an electron multiplier section (11) with one or more microchannel plates and a dynode stage having secondary electron emission. This structure makes it possible to obtain an amplification which is higher than the amplification obtainable with only the electron multiplier section while maintaining the instantaneously obtained characteristics and special resolving power associated therewith.