JP2000223008A - Secondary electron multiplication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase degree of freedom for handling, improve productivity, and provide good characteristic with good reproductivity, by forming zinc oxide particles having respective independent structures on a substrate in an electrochemical method. SOLUTION: When an electrochemical method is used, for example, an electroless deposition method, an electrolytic deposition method, and a hydrothermal synthesis can be employed. Among these, the electroless deposition method is most preferably employed for forming of zinc oxide particles even if a substrate is an insulator, from aspects that the zinc oxide particles are directly easily formed, the zinc oxide particles are easily formed in independent structures, and a device used for forming the zinc oxide particles is very simple. The term 'independent structure' means a state that the zinc oxide particles formed on the substrate do not directly abut, to each other structurally or electrically. Since the zinc oxide particles have such structure, differently from a normal film structure, high resistivity can be held between the zinc oxide particles, and high voltage can be impressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a secondary electron multiplier useful for detecting charged particles such as ions and electrons.

[0002]

2. Description of the Related Art First, the principle of a secondary electron multiplier as the background of the present invention will be described. The secondary electron multiplier includes a tubular type, a parallel plate type, a channel plate type and the like. Here, a tubular type as shown in FIG. 1 will be described.

As shown in FIG. 1, a tubular secondary electron multiplier 6 comprises a ceramic semiconductor 1 having a secondary electron emission capability.
And this constitutes a continuous dynode. An appropriate voltage is applied between the input terminal 2 and the output terminal 3. Now, when one incident electron 4 enters from the input terminal 2, the incident electron 4 is pulled by an applied voltage applied between the input terminal 2 and the output terminal 3, and the dynode surface of the secondary electron multiplier 6. (The inside of the tube) and two or more secondary electrons are emitted. Then, by each of the secondary electrons repeat the same process, the secondary electrons in the so-called Nezumizan expression is multiplication, in the finally output terminal 3 is released as 10 ⁶ or so electrons, the collector 5 Complemented by

The above-described secondary electron multiplier 6 has been
Ceramic ceramic barium titanate-based semiconductor porcelain and zinc titanate-based semiconductor porcelain have been put to practical use. Among them, the secondary electron emission of the zinc titanate-based semiconductor porcelain is considered to occur by the following process. In other words, it is considered that the secondary electrons are emitted when the charged particles accelerated by the applied voltage collide with the low-resistance zinc oxide particles contained in the high-resistance zinc titanate porcelain. ing. Such ceramics have excellent characteristics such as high gain, excellent heat resistance and impact resistance, and small size.

In addition to such ceramics, a secondary electron multiplier is formed by using a lead-containing glass which is heat-treated in a reducing gas to precipitate a lead component on the glass surface. Has been This lead-containing glass has a characteristic that it can be easily formed into an arbitrary shape and can be produced by a simple manufacturing method.

[0006]

However, the above-mentioned conventional secondary electron multiplier has the following problems.

That is, in the case of using a ceramic semiconductor such as zinc titanate porcelain, since the material is ceramics, the surface and the inside have a large number of voids (pores). In general, it is difficult to produce dense ceramics having uniform crystal grains with good reproducibility. In order to improve and stabilize the characteristics of the secondary electron multiplier, the development of ceramics with a small number of pores and a uniform crystal grain size has been desired, but this has not yet been fully solved .

Further, the channel plate type secondary electron multiplier has the problem that the shape of the channel plate is complicated, the processing thereof is very difficult, and the productivity is poor.

Further, in the secondary electron multiplier formed using lead-containing glass, since lead is used, there are problems in handling during production and disposal.

Accordingly, it is an object of the present invention to provide a secondary electron multiplier which has a high degree of freedom in handling, is excellent in productivity, and can obtain good characteristics with good reproducibility.

[0011]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of the above-mentioned problems, and as a result, by forming zinc oxide particles on a substrate by an electrochemical method, the above-mentioned object has been achieved. The inventors have found that an achievable secondary electron multiplier can be obtained, and have completed the present invention.

Examples of the electrochemical technique referred to in the present invention include an electroless plating method, an electrolytic plating method, and a hydrothermal synthesis method. Among them, it is easy to form zinc oxide particles directly even when the substrate is an insulator, easy to form zinc oxide particles in an independent structure, and very simple equipment for forming zinc oxide particles is sufficient. From the viewpoint of
Most preferably, the zinc oxide particles are formed by an electroless plating method.

The term "independent structure" as used herein refers to a state where the zinc oxide particles formed on the substrate are not in direct structural or electrical contact with each other. Since the zinc oxide particles have such a structure, a high resistance can be maintained between the zinc oxide particles, unlike a normal film structure, so that a higher voltage can be applied, and as a result, a high voltage can be applied. A continuous dynode of gain can be realized.

In order to reduce the resistance of the zinc oxide particles, it is preferable that the zinc oxide particles are doped with at least one of B, Al, Ga, In and Tl. By this doping, the resistance of the zinc oxide particles is reduced, the number of secondary electrons emitted by collision of incident electrons with the continuous dynode can be increased, and the gain of the multiplier can be improved.

[0015] Examples of the doping method include an ion implantation method, a thermal diffusion method, and ion uptake when forming zinc oxide particles. Among these, in the case of forming zinc oxide particles by electroless plating, since the above-described dopant ions can be taken in simultaneously with the formation of the particles, it is preferable to use this method from the viewpoint of cost reduction and the like.

As described above, by forming zinc oxide particles by an electrochemical method, it is possible to form zinc oxide particles even on a substrate having no pores, such as glass, so that a multiplication apparatus can be used. The characteristics can be improved. Further, by keeping the composition of the plating bath uniform, it is possible to easily realize the uniformity of the characteristics of each multiplier. Further, a relatively simple apparatus is required for forming the zinc oxide particles. In addition, since lead is not used, a multiplier having a high degree of freedom in handling can be provided.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, as a preferred embodiment of the present invention, a case will be described in which a secondary electron multiplier is manufactured using zinc oxide particles deposited on an insulating substrate by electroless plating. I do.

All the chemicals used in the present embodiment use reagent grade (Nacalai Tesque, Inc.). Also,
The substrate is a hollow Pyrex glass tube (length 100 m)
m, outer diameter 3 mm, inner diameter 1.5 mm) and degreasing, etching, sensitizing, and catalyzing are performed in a conventional manner.

[0019]

[Experimental Example] An electroless plating solution for preparing zinc oxide particles having the following composition was placed in a 200 mL tall beaker, set in a thermostat, and then a sample was prepared under predetermined conditions.

Zinc nitrate 0.05 mol / L Dimethylamine borane 0.05 mol / L (adjusted to pH 6 with a 1% by weight aqueous solution of sodium hydroxide) Dip the above glass tube in the above electroless plating solution, Was maintained at 60 ° C., and electroless plating was performed for 30 minutes. As a result, transparent deposits were observed inside and outside the cylinder of the Pyrex glass tube. When the attached matter was measured by an X-ray diffraction method, a peak due to crystalline zinc oxide was observed.
Furthermore, in observation with a scanning electron microscope, 50 to 200 n
Hexagonal column-shaped particles having a diameter of about m and independent structures were observed.

As shown in FIG. 2, metal foils 21 and 22 made of aluminum are wound around both ends of the cylinder of the sample obtained under the above-mentioned conditions, and a part of the coating of the zinc oxide particles between the aluminum foils is removed. A zinc oxide particle removing unit 23 was provided by removing with a 0.1 mol / L hydrochloric acid solution, and a secondary electron multiplier 20 was manufactured.

Next, the secondary electron multiplier 20 was incorporated in a circuit as shown in FIG. 3, and the multiplication gain of the secondary electrons was measured. In the figure, 9 is a multiplier, 10 is a filament,
11 is a collector, 12 is a monitor collector, 13 is a filament power supply, 14 is a drawing power supply, 15 is an acceleration power supply, 16 is a multiplication power supply, 17 is a collector power supply, 18 is a monitor ammeter, and 19 is a load resistance. , 20 are ammeters for measuring the output current. In the circuit described above, when the incident electron energy was set to 300 eV and the power supply 16 for multiplication was set to 3 KV, and the secondary electron multiplication gain was measured, a gain of 3.5 × 10 ⁶ was confirmed. A secondary electron multiplier of the same shape made of a barium titanate-based semiconductor porcelain that has been conventionally put into practical use was fabricated, and the secondary electron multiplication gain was measured using the same circuit. With a gain of 10 ⁶ , it was confirmed that the secondary electron multiplier manufactured according to the present invention had a gain sufficient for practical use.

Although the above embodiment has been described with reference to a tubular secondary electron multiplier, the present invention is not limited to this embodiment, but may be applied to a flat plate or a channel plate type. It can be widely applied to secondary electron multipliers including the same. Further, although glass is used as a substrate for forming the secondary electron multiplier, a flexible substrate such as an insulating resin may be used.
In this case, the secondary electron multiplier can be treated as flexible, the degree of freedom in designing peripheral devices (assemblies) using the secondary electron multiplier can be increased, and the gain can be varied. It can be.

[0024]

As is clear from the above description, according to the present invention, by forming zinc oxide particles on a substrate by an electrochemical method, secondary electron emission ability can be improved even on a substrate having a complicated shape. Can form zinc oxide particles having
Moreover, the degree of freedom of handling is high, the productivity is excellent,
It is possible to provide a secondary electron multiplier capable of obtaining good characteristics with good reproducibility.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the principle of a secondary electron multiplier.

FIG. 2 is a schematic perspective view showing a secondary electron multiplier according to an embodiment of the present invention.

FIG. 3 is a circuit diagram for measuring the gain of the secondary electron multiplier obtained according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ceramic semiconductor 2 ... Input terminal 3 ... Output terminal 4 ... Incident electron 5 ... Collector

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4K022 AA03 AA33 AA41 BA15 BA25 BA33 CA02 CA03 CA05 CA06 DA01 5C038 BB02 BB06

Claims (3)

[Claims] 1. A secondary electron multiplier comprising zinc oxide particles formed on a substrate by an electrochemical method. 2. The secondary electron multiplier according to claim 1, wherein each of the zinc oxide particles formed on the base has an independent structure. 3. The zinc oxide particles include B, Al, G
3. The secondary electron multiplier according to claim 1, wherein at least one of a, In, and Tl is doped.