DE1539957C - Photo electron multiplier system - Google Patents

Description

If electrons stay in a certain channel, the angle of inclination β and the arrangement of the dynodes must be carefully designed from an electron-optical point of view. In order to achieve the desired guidance of the electrons, N + 1 electrodes must be available for 2V channels.

FIG. 3 shows a practical example of a photoelectron multiplier according to the scheme of FIG. 1, but with three stages of dynode sheets. Exact construction dimensions are given here instead of the reference symbols. The distances and lengths are relative specifications, which can all be multiplied by any common factor. 37 ° was specified for the angle λ and 15 ° for β. Additional amplifier dynodes can be switched in for higher gains.

1 sheet of drawings

Claims (2)

1 2 solved by the fact that the photocathode from a multitude of claims: number of blind-like arranged 'sheets consists of a material with an emissive surface, 1. Photoelectron multiplier system, the depth and inclination of which are such that their to which the 5 projections emerging from the photocathode onto the plane of incidence of light are closed Particles are focused, thereby representing its surface, and that this photocathode denotes, that the photocathode from the blind is a known multiplier system consisting of a large number of sheets arranged in the manner of a blind in one or more rows in the manner of a blind (1) made of a material with emissive neter dynodes is connected downstream, the single surface exists whose depth and inclination are dynodes in length, inclination, shape and spacing are sized so that their projection on the light. are dimensioned so that they are electronically closed all plane represents a closed surface, represent its channels, and that at the end .this and that this photocathode blind (1) is electrically isolated from one another by channels "known multiplier system from one or suction anodes are arranged, which are made by several elements Rows (2, 3) arranged like blinds- 15 electrodes are shielded from each other. As a layer ter dynodes is connected downstream, the single for the surface of the photocathode sheets is CsTe nen dynodes in length, inclination, shape and ab- or an alkali halide are particularly suitable. stand are dimensioned so that they are electronically optically In the drawing is an embodiment of the represent closed channels (8, Sa ... Sc) , system according to the invention shown schematically, and that at the end of these channels separate from 20 Fig. 1 shows the system in its basic mutually electrically isolated suction anodes (4) structure ^ are arranged, which are opposed by electrodes (5) F i g. 2 the geometric arrangement of a photo are shielded from each other. cathode sheet, 2. Photoelectron multiplier system according to FIG. 3 shows a practical embodiment.
Claim 1, characterized in that the 25 On the sheets 1 of the photocathode is an emis sheet (1) of the photocathode a surface of sionable layer, for. B. CsTe, an alkali halo-CsTe or an alkali halide. genid or an alkali-antimony compound is applied. The photoelectrons released by the incident light become the dy- 30 node plates 2, which are at a positive potential located opposite the metal sheets 1, accelerated and trigger secondary electrons there. These are ;; '■■ · ■ to the dynode plates 3 of the next row The invention is a photoelectron accelerated, which in turn is positive compared to the Multiplier system in which the sheets from the photo 35 are loaded and again generate seconds Charged particles emerging from the cathode focus the electrons etc. in front of the photocathode sheets 1 will. lies in the plane of incidence of light, a network 6 higher There are numerous embodiments of such transparency, the potential of which is chosen so that the Multiplier systems are known in which the photoelectrons as completely as possible for amplification stronger dynodes are guided into one another in the shape of a shovel. telt or blind-like are arranged one behind the other. . . ... The dynode sheets of the individual rows 2, 3 etc. The amplifier system is basically in an eva-forming electron-optically closed channels 8, 8a, accomodated vessel. Should photocurrents 86, 8 c etc. At the end of these channels, i.e. at the exit With such a system reinforced, the entire system's gang is each separate In addition to the amplifier, there is also a photocathode in 45 anodes 4 to take the amplified currents. built into the same vacuum vessel. This photo-sorted. These anodes are covered with shielding plates 5 cathode is usually provided on a carrier plate, which is an undesirable transition of the made of translucent material. Which prevent electrons from going from one anode to the other Photo- The anodes 4 can be thin wires, the off- Electrons enter the reinforcing plate as a diffuse bundle. The shielding plates 5 are concave and can core system and are used as an amplified photocurrent at a correspondingly selected potential with be used on an electrode that serves as an anode men. 'Between the individual rows of dynodes are The object of the invention is to arrange photoelectrons, suction nets 7 of high transparency, which receive the potential of the following row from individual juxtaposed 55.
Surface elements of the photocathode emerge, to The carrier plates 1 of the photocathode are reinforced and placed individually on the respective surfaces that they - from the direction of incidence of light from the elements assigned to anodes. seen - form a closed surface. this To solve this problem, as shown in FIG known arrangements are not suitable, since they have a length L of L = D / cos, α. D is the one Systems inadequate separation of the individual distance between the individual channels and α the Enable signal streams. The photo angle of inclination of the electrode, electrons on the way from the photocathode to The blind-like multiplier system with the to the entrance of the system are strongly distracted between suction nets is known per se, and in addition, the light that generates the photocurrent 65 These systems have so far only been used to amplify generated, already used in the carrier plate for photocopying in the single-channel system. There is so- cathode scattered. probably the angle of inclination β and the arrangement of the According to the invention, the task set for the individual dynode levels is not critical. But should they