JPS5919410B2 - gas flow counter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises: an anode wire is insulated and stretched in a metal container having a radiation entrance window; a counting gas is passed through the container;
The present invention relates to a gas flow counter in which a high voltage is applied between the container and an anode wire using the container as a cathode, and radiation incident on the container through an entrance window is counted.

In this type of conventional gas flow counter, the container is made of aluminum, and the anode wire is made of gold-plated tungsten wire.The container is used as a cathode, and a voltage of, for example, 1000 to 2000 V is applied between the cathode and the anode wire. High voltage is applied.

In this case, a counting gas is passed through the container, and the radiation incident on the container through the radiation entrance window is detected in the form of pulses by the anode beam.

As the counting gas, for example, PR gas (argon gas + methane gas), Q gas (helium gas + isobutane gas), propane gas, methane gas, etc. are used.

By the way, in this type of gas flow counter, when setting the high voltage to be applied between the cathode container and the anode wire, a plateau characteristic indicating the relationship between the applied voltage and the counting rate is investigated.

This plateau characteristic depicts the counter output (count rate) obtained when a radiation source with a constant count rate N is kept close to the radiation entrance window and the applied voltage is gradually increased. The characteristic line will be as shown in Figure 1.

In FIG. 1, the applied voltage a is referred to as the discharge starting voltage.

The voltage in the section where the counter output is almost flat with respect to the set voltage and the applied voltage is recognized.

However, as a result of various experiments, in the conventional gas flow counter having the above-mentioned configuration, that is, the cathode is an aluminum base plate, it has been found that PR gas, methane gas, and propane gas are used as the counting gas. When it is allowed to flow, a plateau characteristic as shown in Figure 1 is obtained, but when Q gas is allowed to flow as a counting gas, it has been found that continuous discharge occurs, making it unusable. did.

In other words, Figure 4 shows the experimental results of plateau characteristics.
A conventional gas flow counter has a plateau characteristic as shown by characteristic line a, and there is no flat section.

By the way, when Q gas is used as a counting gas, compared to other gases, the applied voltage can be set lower and the amplification degree of the gas is greater, so there is no need to maintain a scaler on the counter output side. It has many advantages such as good.

Therefore, it is often required to use Q gas as a counting gas.

The present invention has been made in view of these points, and an object of the present invention is to provide a gas flow counter that can obtain good plateau characteristics even when Q gas is used as a counting gas.

In order to achieve this objective, the inventor of the present invention has conducted numerous studies and various experiments, and has found that good plateau characteristics can be obtained by applying a nickel film to the inner wall surface of the cathode container. I found it.

In preferred embodiments of the invention, the nickel film comprises a vapor deposited film of nickel.

In another preferred embodiment of the invention, the nickel film comprises a nickel plated film.

Next, one embodiment of the present invention will be described in detail based on the drawings.

FIG. 2 is a longitudinal cross-sectional view of one embodiment of the present invention, and FIG. 3 is a cross-sectional view thereof.

A plurality of anode wires 1 are insulated and stretched around the container 2.

This container 2 is made of aluminum and is used as a cathode.

At this time, this container 2 is grounded.

The anode wire 1 is made of a tungsten wire plated with gold, and a high voltage H (V) is applied between the anode wire 1 and the container 2.

The container 2 is provided with a radiation entrance window 3 made of a thin film.

4 is an electric field correction tube, and 5 is an insulator that insulates between the anode wire 1 and the container 2.

6 is a protection plate for the entrance window 3, and 7 is an O-ring.

A counting gas is introduced into this container 2 from a gas port 8 and is led out through a gas outlet 9.

In the present invention, a nickel film 10 is provided on the inner wall surface of the container 2.
The nickel film 10 is made of a nickel vapor deposited film or a nickel plated film.

The radiation that enters the container 2 through the entrance window 3 thus produces an electrical discharge within the container 2 and is extracted from the anode wire 1 in the form of electrical pulses.

FIG. 4 shows the experimental results of the beta ray plateau characteristic when Q gas is used as the counting gas, and the characteristic line is the plateau characteristic line of one embodiment of the present invention.

According to the experimental results shown in FIG. 4, it was found that good plateau characteristics could be obtained simply by applying a nickel film to the inner wall surface of the container 2.

At present, it is unclear why the good plateau characteristics shown by the characteristic line in Figure 4 can be obtained by simply applying a nickel film to the inner wall surface of the container 2. be.

FIG. 5 shows experimental results of plasticity when PR gas was used as the counting gas in one embodiment of the present invention.

As is clear from the experimental results shown in FIG. 5, in the present invention, not only Q gas but also other gases such as PR gas can be used as the counting gas.

As explained above, according to the present invention, by simply applying a nickel film on the inner wall surface of the cathode container, even when Q gas is used as the counting gas, all the characteristic lines in FIG. As shown, good plateau characteristics are obtained.

[Brief explanation of the drawing]

Fig. 1 is a general plateau characteristic diagram of a gas flow counter, Fig. 2 is a vertical cross-sectional view of an embodiment of the present invention, Fig. 3 is a cross-sectional view thereof, and Fig. 4 uses Q gas as the counting gas. Fig. 5 is a characteristic diagram showing the experimental results for explaining the difference in plateau characteristics between a conventional gas blow counter and an embodiment of the present invention in the case where PR gas is used as the counting gas. It is a plateau characteristic diagram of one example. 1... Anode wire, 2... Container, 3...
...Radiation entrance window, 5...Insulator, 8...
...Gas inlet, 9...Gas outlet, 10...
...Nickel film.

Claims (1)

[Claims] 1. An anode wire is insulated and stretched in a metal container having a radiation entrance window, a counting gas is passed through the container, and the container is used as a cathode between the container and the anode wire. 1. A gas flow counter for counting radiation incident into the container through the entrance window by applying a high voltage to the gas flow counter, characterized in that the inner wall surface of the container is coated with a nickel film. 2. A gas flow counter according to claim 1, wherein the nickel film is a vapor-deposited nickel film. 3. The gas flow counter according to claim 1, wherein the nickel film is a nickel plating film. 4. A gas flow counter according to any one of claims 1 to 3, characterized in that the counting gas is Q gas. 5. A gas flow counter according to any one of claims 1 to 4, wherein the container is made of aluminum. 6. A gas flow counter according to any one of claims 1 to 5, wherein the anode wire is a gold-plated tungsten wire.