JPH0644474B2 - Electron multiplier - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electron multiplying device utilizing secondary electron emission characteristics used as an electron multiplying device such as a photomultiplier tube.

(Prior Art) A Venetian blind type dynode is known as a device for multiplying electrons by closely disposing dynodes in a relatively narrow space.

FIG. 11 is a sectional view showing a part of an electron multiplying device using a Venetian blind dynode.

The figure mainly shows the i-th stage and the i + 1-th stage, which are mainly taken out, of the multiplication device which is composed of a stack of meshes and dynodes of a large number of stages.

In the figure, Mi is i arranged at right angles to the incident direction of electrons.
The th mesh, Dyi is the i th dynode,
Similarly, Mi + 1 is the i + 1th mesh, and Dyi + 1 is the i + 1th dynode.

The inclination of each plate of the (i + 1) th dynode is opposite to that of the ith dynode, and dynodes having different inclinations are alternately arranged with the mesh in between.

Each of the meshes is manufactured by making holes by masking and photoetching a material metal plate.

Further, each dynode group is processed into a so-called Venetian blind type by press shaping, and is made to function as a secondary electron emission electrode.

The mesh Mi and the dynode Dyi are connected and the potential Vi
, The mesh Mi + 1 and the dynode Dyi
+1 is connected to the potential Vi + 1 (> Vi).

Secondary electrons generated by the electrons incident on the i-th dynode Dyi are incident on the slope of the lower dynode Dyi + 1 via the mesh Mi + 1 and are further multiplied.

(Problems to be Solved by the Invention) In the electron multiplying apparatus using the Venetian blind type dynode, it is possible to provide a certain level of incident position resolution performance by increasing the number of slopes forming each dynode. You can

Secondary electrons from the dynode Dyi are once decelerated on the back surface of the adjacent slope, accelerated by the next mesh Mi + 1, and incident on the dynode Dyi + 1. The deceleration of electrons in this process causes an increase in the electron transit time and the spread of the electron transit time.

Further, since there is a proportional relationship between the electrode size (distance) and the electron transit time and the spread of the electron transit time, it is necessary to reduce the shape and interval of the dynodes in order to reduce this.

However, the accuracy of metal processing of the dynode is limited, and it is difficult to further reduce the electron transit time and the electron strike time spread and improve the position resolution performance.

An object of the present invention is to provide an electron multiplying device which can solve the above-mentioned problems.

(Means for Solving the Problems) In order to achieve the above object, an electron multiplying device according to the present invention includes an insulating substrate having a first surface and a second surface parallel to each other, and A plurality of through holes formed in the substrate having a first hole surface that maintains an obtuse angle with respect to the first surface and a second hole surface that faces the first hole surface, and the first holes of each of the through holes. The secondary electron emission layer formed on the surface from the first surface side of the substrate, and the secondary electron emission layer on the surface of the second hole of each of the through holes are separated from the secondary electron emission layer to the second surface side. The formed conductive layer, first connecting means for connecting the secondary electron emission layers on the first surface of the substrate, and second connecting means for connecting the conductive layers on the second surface of the substrate. Electrons that enter the connection means and one of the through holes from the first surface side of the substrate are connected to the secondary electron emission layer. It is composed of means for applying a voltage between the first and second connection means so as to accelerate the multiplied electrons in the direction of the second surface of the substrate.

(Example) Hereinafter, the present invention will be described in more detail with reference to the drawings.

FIG. 1 is a plan view of a first embodiment of an electron multiplying element according to the present invention, FIG. 2 is a side view showing a state of use of the element of the first embodiment, and FIG. 3 is a drawing of the first embodiment. It is the perspective view which expanded and showed a part of element.

A flat insulating substrate 1 made of glass (SiO ₂ ) is provided with a large number of through holes 2 each having a substantially circular opening.

The through hole 2 is provided with an inclination on the surface on which electrons are incident.

This through hole 2 is processed by the photoetching method as follows.

A latent image corresponding to the shape of the hole is formed in the glass by irradiating the insulating substrate 1 with ultraviolet rays obliquely through a negative in which the pattern of the opening and the separation groove is formed.

Then, heat treatment is performed to crystallize the latent image portion.

Further, by acid treatment, only the crystal part is dissolved and a through hole having a shape corresponding to the negative shape is obtained.

By vacuum-depositing antimony (Sb) on the slope of the through-hole 2 that maintains an acute angle with the surface of the substrate 1,
The secondary electron emission layer 5 is formed.

The secondary electron emission layer 5 is formed so as not to reach the lower opening of the through hole, and is insulated from the lower surface of the substrate 1.

Also, aluminum (Al) is vacuum-deposited on the slope of the through hole 2 which maintains an obtuse angle with the surface of the substrate 1 and is separated from the secondary electron emission layer 5 by the separation groove 7. Thus, the acceleration electrode layer 6 is formed.

The acceleration electrode layer 6 is formed so as not to reach the upper opening of the through hole, and is insulated from the upper surface of the substrate 1.

On the first surface of the insulating substrate 1, connecting means 3 for connecting a large number of secondary electron emission layers 5 formed as described above to a power source, and on the second surface (back surface) of the insulating substrate 1 are many. Connection means 4 for connecting the individual acceleration electrode layers 6 to a power source are formed.

Next, the electron multiplying function of the device of this embodiment will be described mainly with reference to FIG.

The example element is placed in a vacuum, and the connecting means 3 and the connecting means 4 are connected to the power supplies 10a and 10b, respectively. Power supply 1
The voltage of 0b is larger than the voltage of the power supply 10a (V ₂ > V
₁ ).

Therefore, an acceleration electric field is formed from the secondary electron emission layer 5 toward the acceleration electrode layer 6.

The electrons that have entered from the first surface of the embodiment element enter the secondary electron emission layer 5 and are multiplied.

Normally, the element of this embodiment is not used alone as described above but is used by stacking a plurality of elements as described later.

FIG. 4 is a sectional end view of an electron multiplying device constructed by using the three elements of the embodiment.

The first electron multiplication element I and the second electron multiplication element II are
The electron multiplying element II is fixed so that the inclination of the through hole is opposite to the inclination of the first electron multiplying element I.

In the second electron multiplying element II and the third electron multiplying element III, the direction of the inclination of the through hole of the third electron multiplying element III is opposite to that of the second electron multiplying element II and the first electron multiplying element II is used. It is fixed so as to be in the same direction as the inclination of the multiplication element I. Connect the power 10a~10d the connection portion of the electron multiplying device _{(V 3> V 2> V} 1> V 0).

As a result, the acceleration electrode layer 6 of the first electron multiplying element I and the secondary electron multiplying layer 5 of the second electron multiplying element II have the same potential (V ₁ ). Accelerating electrode layer 6 of the first electron multiplying element I
Serves as an electrode for accelerating the electrons multiplied by the secondary electron multiplication layer 5 of the first electron multiplication element I to the secondary electron multiplication layer 5 of the second electron multiplication element II.

This relationship is common with the structure in which the Venetian blind type dynode is provided with a mesh electrode for acceleration of the same potential on the front surface of the dynode.

Further, the acceleration electrode layer 6 of the second electron multiplying element II and the secondary electron multiplying layer 5 of the third electron multiplying element III have the same potential (V ₂ ).

In the electron multiplying device, the electrons (60) incident on the electron multiplying layer 5 of the first electron multiplying element I from above are multiplied by the electron multiplying layer 5 and the second electron multiplying element II It is incident on the electron multiplication layer 5 to be multiplied. The electrons multiplied by the electron multiplication layer 5 of the second electron multiplication element II are the third electron multiplication element III.
Is multiplied by the electron multiplication layer 5.

In this way, the light is multiplied by the second and third multiplication elements and emitted from the corresponding output aperture.

A small number of electrons generated near the entrance aperture are
The secondary electrons may be trapped by the acceleration electrode layer 6 of the first electron multiplication element I before reaching the multiplication layer 5 of the next stage.

However, most of the electrons reach the multiplication layer 5 in the next stage and are multiplied. There is no problem if a very small number of electrons are trapped in the acceleration electrode layer 6 of the first electron multiplying element I. If the accelerating electrode layer 6 is not provided, a very small number of charges may adhere to the wall surface of the hole and disturb the electric field in the vicinity thereof, so that a very small number of electrons are generated in the first electron multiplier I. It is considered that the operation is more stable if the accelerating electrode layer is provided even if it is captured by the accelerating electrode layer 6.

FIG. 5 is a sectional view showing an embodiment of a photomultiplier tube constructed by mounting the above-mentioned multiplication device in a vacuum container.

A photocathode 14 is formed on the inner surface of the entrance window of the vacuum container 9.

The anode 15 corresponding to the output opening of the third electron multiplying element III
Is provided.

The operating power supply is connected to each electron multiplier element as described above, and the anode 15 is operated by applying the highest voltage.

FIG. 6 is a plan view of a second embodiment of the electron multiplying device according to the present invention. In this embodiment, the shape of the opening of the through hole 2 is substantially square.

The mask pattern becomes simpler, and the aperture area for incident electrons can be made larger than in the first embodiment described above.

FIG. 7 is a plan view of a third embodiment of the electron multiplying device according to the present invention. In this embodiment, the shape of the opening of the through hole 2 is square.

Two-dimensional information cannot be obtained with the electron multiplier having such a shape, but there is an advantage that sufficient sensitivity can be secured.

FIG. 8 is a plan view of a fourth embodiment of the electron multiplying device according to the present invention. In this embodiment, the shape of the opening of the through hole 2 is 6
It has a square shape.

Two-dimensional information cannot be obtained with the electron multiplier having such a shape, but there is an advantage that sufficient sensitivity can be secured.

FIG. 9 is a sectional view showing another embodiment of the photomultiplier tube constructed by using the above-mentioned electron multiplier. The photocathode 14 of the vacuum container 9 is arranged so that the input surface (first surface) of the electron multiplication element at the forefront faces, and the multiplied output multiplied in multiple stages is collected by the anode 15.

FIG. 10 is a sectional view showing still another embodiment of the photomultiplier tube constructed by using the above-mentioned electron multiplier.

This embodiment is used in combination with a conventionally known box type dynode 17. The input aperture 16 of the photomultiplier is fixed toward the box-shaped dynode 17. Reference numeral 15 is an anode for collecting the multiplied electrons.

(Effects of the Invention) As described in detail above, the electron multiplying device according to the present invention includes an insulating substrate having a first surface and a second surface which are parallel to each other and a first surface of the substrate. A plurality of through holes formed in the substrate having a first hole surface that maintains an obtuse angle and a second hole surface facing the first hole surface, and a first hole surface of the substrate on the first hole surface of each of the through holes. 1. A secondary electron emission layer formed from the surface side of No. 1 and a conductive layer formed on the surface of the second hole of each through hole and separated from the secondary electron emission layer on the second surface side. A first connection means for connecting the respective secondary electron emission layers on the first surface of the substrate, a second connection means for connecting the respective conductive layers on the second surface of the substrate, and the substrate The electrons that have entered one of the through holes from the first surface side of are multiplied by the secondary electron emission layer and are multiplied. And a means for applying a voltage between the first and second connecting means so as to accelerate the electrons in the second surface direction of the substrate.

That is, since the electron multiplying element according to the present invention is constructed as described above, a small electron multiplying device can be formed by using this.

When the electron multiplying device is made smaller, the electron transit time and the spread of the electron transit time can be reduced, so that the multiplier device excellent in time resolution can be obtained.

Also, as described above, various photomultiplier tubes can be manufactured using the electron multiplier.

Since these photomultiplier tubes are excellent in position resolution and time resolution, they can be widely used for various measurements.

Generally in order to obtain the electron multiplication factor (output Electronic / incident electron) 10 ⁶ of the electron multiplier device is required, the electron multiplication device of the present invention may Stacking 10 sheets. Since the thickness of one electron multiplier described above can be set to about 0.5 mm,
An electron multiplying device can be constructed with about 5 mm.

This thickness is ⅛ as compared with the thickness required for the same multiplication with the conventional electron multiplier.

[Brief description of drawings]

FIG. 1 is a plan view of a first embodiment of the electron multiplying device according to the present invention. FIG. 2 is an end view of the first embodiment. FIG. 3 is an enlarged perspective view showing a part of the device of the first embodiment. FIG. 4 is an end view showing an embodiment of a multiplication device constructed by using a plurality of the first electron multiplication elements. FIG. 5 is a sectional view showing an embodiment of a photomultiplier tube constructed by mounting the above-mentioned multiplication device in a vacuum container. FIG. 6 is a plan view of a second embodiment of the electron multiplying device according to the present invention. FIG. 7 is a plan view of a third embodiment of the electron multiplying device according to the present invention. FIG. 8 is a plan view of a fourth embodiment of the electron multiplying device according to the present invention. FIG. 9 is a cross-sectional view showing another embodiment of the photomultiplier tube constructed by mounting the electron multiplier element in the vacuum container. FIG. 10 is a cross-sectional view showing still another embodiment of the photomultiplier tube configured by mounting the electron multiplier in the vacuum container. FIG. 11 is a sectional view showing a conventional Venetian blind type dynode. DESCRIPTION OF SYMBOLS 1 ... Insulating substrate, 2 ... Through hole 3 ... Connecting means formed on the first surface of the insulating substrate 4 ... Connecting means formed on the second surface of the insulating substrate 5 ... Secondary electron emission layer 6 ... Accelerating electrode layer 7 ... Separation groove 9 ... Vacuum container 10a to 10d ... Power supply 14 ... Photocathode, 15 ... Anode 17 ... Box-shaped dynode 70 ... Electron multiplier

Claims (4)

[Claims] 1. An insulating substrate having a first surface and a second surface parallel to each other, a first hole surface that maintains an obtuse angle with respect to the first surface of the substrate, and a surface facing the first hole surface. Second
A plurality of through holes formed in the substrate having a hole surface, a secondary electron emission layer formed on the first hole surface of each of the through holes from the first surface side of the substrate, and the through holes A conductive layer separated from the secondary electron emission layer on the surface of the second hole and formed on the second surface side is connected to each of the secondary electron emission layers on the first surface of the substrate. The first connecting means, the second connecting means for connecting the conductive layers on the second surface of the substrate, and the electron incident on one of the through holes from the first surface side of the substrate Electron multiplication comprising means for applying a voltage between the first and second connection means so as to multiply by the next electron emission layer and accelerate the multiplied electrons in the direction of the second surface of the substrate. element. 2. The shape of the openings on the first surface of the substrate of the through holes is circular, square, or hexagonal, and the openings are densely and regularly arranged.
An electron multiplying element according to the item. 3. The electron multiplying device according to claim 1, wherein the insulating substrate has SiO ₂ as a main component, and the through hole is processed by photoetching. 4. The electron multiplying device according to claim 1, wherein a groove is provided between the secondary electron emitting layer and the conductive layer.