JPS6030062B2 - Secondary electron multiplier - Google Patents

Description

[Detailed description of the invention] A planar silk made of an alloy with a high secondary electron emission ratio such as copper beryllium or silver 7 gnesium is used as a dynode, and the dynodes are stacked in parallel and spaced apart, and a higher voltage is applied in sequence. Since such a secondary electron multiplier can be formed into a uniform structure over a large incident surface, it has the characteristic of having a uniform secondary electron multiplication factor with respect to the position of the primary electron incident surface.

FIG. 1 is a diagram showing the structure of the dynode of the above-mentioned secondary electron multiplier and the trajectory of electrons.

That is, 1, 2, and 3 are silk-like dynodes, and higher potentials are applied in this order. 5 is the orbit of the electron.

Electrons emitted from the first-stage dyno collide with the second-stage dynode 2 to emit secondary electrons, but since the secondary electron surface faces the front-stage dyno, sufficient acceleration is not achieved at the time of emission. Therefore, the response speed is slow, and temporal diffusion of the output signal occurs due to the influence of the initial velocity distribution of the secondary electrons. The present invention is a secondary electron multiplier having a silk-like dynode, which does not have the above-mentioned drawbacks, that is, has a long response speed and a small temporal dispersion of the output signal.

Furthermore, the dynode of the secondary electron multiplier of the present invention can be easily manufactured. FIG. 2 is a diagram showing the longitudinal cross-sectional structure of the dynode and the electron trajectory of the secondary electron intensifier of the present invention, and FIG. 3 is a diagram showing the secondary electron multiplier of the present invention viewed from the direction of electron incidence. It is a diagram.

That is, FIG. 2 is a sectional view taken along line A-A in FIG. 10
, 20 and 30 are conductive silk, and constitute support parts for the first stage dynode 6, the second stage dynode 7 and the third stage dynode 8, respectively.

11, 12, 13, 21, 22, 23, 24, 31, 3
2 and 33 are secondary electron emitters consisting of a rotational ellipsoid or rotationally symmetrical, with one end of the axis of rotation at the intersection of silk 10, 20 or 30, and one end of the axis of rotation perpendicular to the silk. It hangs down on the side of the surface.

Also, when viewed from the direction of incidence of primary electrons, as shown in FIG. 3, the intersection point of the second stage dynode 7 should overlap with the center of the mesh of the first stage dynode 6, and as shown in FIG. , the first stage dynode 6 and the second stage dynode 7 are
They are stacked at intervals narrower than the length of the secondary electron emitters.

The third stage dynode 8 is also installed in the same manner as the relative positional relationship between the first stage dynode 6 and the second stage dynode 7 in relation to the second stage dynode 7. 40 is an electron collection electrode.

The first stage dynode 6 is added to the dynode having the structure as described above.
, the second-stage dynode 7, the third-stage dynode 8, and the collection electrode 40 are given higher voltages in this order, the electrons fly along the trajectory shown by the arrow 50, and each time they collide with each dynode, the number of electrons increases. The voltage increases several times and is finally collected at the collecting electrode, and its magnitude is detected as a voltage generated across the resistor 9.

As can be understood from the above explanation, the dynode of the secondary electron multiplier of the present invention is provided with a silk of the same potential on the front stage side, which annularly surrounds the rotating oval secondary electron emitter of the front stage dynode. , and since the dynode and the front-stage dynode face each other behind that part, it is easy to accelerate the secondary electrons emitted by the front-stage dynode.

Therefore, as a signal amplifier, the response is long and the temporal spread of the output signal is small. Moreover, although the case where the secondary electron emitter is a rotating ellipsoid or a rotationally symmetrical body has been described above, it may also be a pyramid or a polyhedron made by joining the above-mentioned pyramids at the base, with each face facing the center of the mesh.

Next, a method for easily manufacturing the dynode of the present invention will be described.

Prepare metal silk with a predetermined pitch in advance, melt a metal such as antimony or bismuth that will be the material of the secondary electron emitting surface, and then add the metal silk to the melt of the above metal. Dip it, keep it level and pull it out.

The metal melt gathers at the intersections of the mesh due to surface tension and hangs down due to gravity. Furthermore, if a voltage is applied between the metal liquid and the net, the coulombs will be dispersed, making it possible to make it hang down even more efficiently. After that, if it is rapidly cooled, it becomes a dynode shape as shown in FIG. 2, 6, 7, and 8. Therefore, if such dynodes are stacked at a predetermined interval, sealed in a vacuum container together with collecting electrodes, and the surface of antimony or bismuth is activated with an alkali metal, it becomes a secondary electron emitting surface and becomes a secondary electron multiplier. is obtained. As described above, in the present invention, a dynode in which a secondary electron emitter is suspended perpendicularly to the plane at each intersection point of conductive silk stretched in a plane is arranged such that the intersection points of the silk of one dynode are adjacent to each other. A secondary electron beam that has a uniform multiplication factor with respect to the position of the incident surface of the primary electrons stacked opposite to the mesh of the dynode and with an interval narrower than the length of the secondary electron emitter, has a long response, and has small temporal diffusion. It is a secondary electron multiplier.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional structural diagram of a conventional secondary electron multiplier having a silk-like dynode, and 4 is an electron collecting electrode. FIG. 2 is a vertical cross-sectional structural diagram of the secondary electron multiplier of the present invention, and FIG. 3 is a plan view of the secondary electron multiplier of the present invention shown in FIG. State map 2nd map

Claims (1)

[Claims] 1 At each intersection point of a conductive network stretched in a plane, a dynode with a secondary electron emitter hanging perpendicular to the plane is placed so that the intersection point of one dynode network is opposite to the network of an adjacent dynode. , and stacked at intervals narrower than the length of the secondary electron emitters.