JPS595983A - Proportional counter - Google Patents

Abstract

PURPOSE:To widen a usable temp. range, by a method wherein two coaxial cables are attached and the central conductor of one cable is connected to an anode while the central conductor of the other one is connected to a cathode and voltage is applied to the cathode and the anode in an allotted state. CONSTITUTION:When voltage required in operating a proportional counter is set to VO and voltage with +VO/2 and voltage of -VO/2 are supplied by two DC high voltage power sources 105a, 105b, because voltage VO is applied between the cathode 1 and the anode 2 of the proportional counter, this proportional counter is normally operated while an electric pulse signal generated in the proportional counter is amplified by an amplifier. When the amplified pulse signal is counted by a counting circuit, the counting of radioactive rays can be carried out. On the other hand, because voltages +VO/2 applied to coaxial cables 6a, 6b may be the half of the operation voltage VO of the proportional counter, the possibility of the generation of a minute discharge pulse in the cable becomes extremely small and said counter can be sufficiently used even at a temp. higher than a conventional limit environmental temp.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a proportional counter for measuring radiation, particularly to a proportional counter that can be used at high temperatures.

A conventional device of this type is shown in FIG. In the figure, (1) I/line-shaped anode, (2) an anode (1
) coaxially with a cylindrical cathode electrically insulated from the anode <1), (3) an ionizing gas sealed in the space between the cathode and the anode, and (4) I or The airtight case (6) that houses the cathode and anode while being electrically insulated from them is a double-shielded coaxial cable attached to one end of the airtight case, with the center conductor (7) connected to the anode and the inner shield. The conductor (8) is electrically connected to the cathode and the outer shield conductor (9) to the airtight case.

In the figure, "(101)" is a preamplifier, inside which is an amplifier circuit (t02), a resistor (108) and a capacitor (10
4) are connected as shown in the figure. (105) is a DC high voltage power supply, and as shown in the figure, the preamplifier (101) and DC high voltage power supply (105) are connected to measure radiation.

That is, a high DC voltage is applied between the cathode and anode of a proportional counter tube using a DC high voltage power supply, and the ionized charges generated in the gas between the cathode and anode due to radiation are collected on the electrodes while amplifying the gas, resulting in an electrical pulse. After the signal is amplified by an amplifier circuit (102), it is counted by a counting circuit (not shown) to measure radiation.

By the way, when proportional counter tubes are used in environments with strong radiation or high temperatures, organic insulators that are commonly used as insulating materials for coaxial groups cannot be used because of their poor radiation resistance and heat resistance, so alumina, magnesia, etc. of inorganic insulators are used. However, the withstand voltage characteristics of this inorganic insulated cable are not very good, and when the applied voltage increases, minute pulsed discharges occur within the group. The minute discharge pulses within this cable are the signals generated by the proportional counter tube (similar to the Luss, they are amplified by an amplifier and counted by a counting circuit, so they are indistinguishable from signal pulses and can cause interference in radiation measurement. was.

Furthermore, as shown in Figure 2, the frequency of occurrence of minute discharge pulses within the cable increases as the applied voltage increases.
Furthermore, as the environmental temperature rises, the microdischarge pulse starting voltage decreases, and the frequency of microdischarge and <Russ generation also increases. For this reason, even though they can be used satisfactorily at room temperature, they have drawbacks such as being unable to be used in high-temperature environments due to the generation of minute discharges/pulses.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above.Two coaxial groups are attached, one center conductor is connected to the anode, the other center conductor is connected to the cathode, and the cathode and anode are connected. The purpose of the present invention is to provide a proportional counter that can be used over a wide temperature range by applying voltage in a divided manner.

An embodiment of the present invention will be described below.

In Figure 8, (1) is a linear anode, (2) is an anode (
A cylindrical cathode is arranged coaxially with 1) and electrically insulated from the anode (1), (3) is an ionizing gas sealed in the space between the cathode and anode, and (4) is a cylindrical cathode arranged coaxially with the anode (1). An airtight case (6a) that houses the negative and anodes while being electrically insulated from them
) (6b) is a coaxial cable attached to one end of the airtight case, with its respective center conductor (7a) and (7b)
) are electrically connected to the anode and cathode, respectively, and the outer shield conductors (9a) and (9b) are electrically connected to the airtight case. (101) is 11
It is a stationary amplifier, and inside it, an amplifier circuit (102), resistors (108a) (108b), and a capacitor (104) are installed.
are connected as shown in the figure. (105a) (10
5b) is a DC high voltage power supply with different polarity, and as shown in the figure, it is connected to the center conductor (7
a) Connected to (7b).

Now, if the voltage required to operate the proportional counter tube is Vo, then +vO/2 and -VO are generated by two DC high-voltage power supplies.
If a voltage of /2 is supplied, a voltage of vO will be applied between the cathode and anode of the proportional counter, so the proportional counter will operate normally and the electricity generated within the proportional counter, the pulse signal, will be amplified by the amplifier. After that, radiation can be measured by counting with a counting circuit. On the other hand, since the voltage t applied to the coaxial goople can be half of the operating voltage of the proportional counter, the possibility of minute discharge nozzles occurring within the goople is much smaller, and the conventional limit environmental temperature This means that it can be used satisfactorily even at higher humidity. This will be explained using FIG.

The figure shows a certain temperature T. This is the frequency of micro discharge pulses occurring at

It can be seen from the figure that when a voltage of vO is applied to the cable, a minute discharge pulse is generated, and when the applied voltage is VO/2, no minute discharge pulse is generated. Therefore, unlike the conventional method, with one couple, the voltage V required for the operation of the proportional counter tube is
If 0 is supplied, the minute discharge pulses generated within the cable will cause interference, making it impossible to measure the radiation accurately.
By supplying O/2, the voltage necessary for the operation of the proportional counter tube■ If 0 is applied, no minute discharge pulses are generated within the cable, allowing accurate radiation measurement.In the above example, two cables However, even if the operating voltage distribution is +2Vo/a *-Vo/s, for example, there is a considerable improvement effect, and it is not necessary to distribute it in half. do not have to.

Further, in the above embodiment, the shielding conductor of the coaxial cable attached to the airtight container is single layered, but it may be double layered in order to reduce electromagnetic induction interference. In this case, as shown in Fig. 4, a shield tube (5) is provided between the airtight container and the cathode so as to be electrically insulated from both, and the inner shield conductor (8a) (8b) of the coaxial cable is It will be even more effective if it is electrically connected to the

As described above, the present invention includes a case that houses a cathode and anode and is electrically insulated from the cathode and anode, and two coaxial cables that are housed in this case, and the center conductor of one of the coaxial groups is To the above anode, the other center conductor t: + knee 1
z electrically connected to the cathode, external shield conductors of the two coaxial cables are electrically connected to the case, and a positive voltage is applied to the anode with respect to the case,
1) Since the negative voltage is applied to the cathode of the above case, the voltage necessary for the operation of the proportional counter tube can be shared between the two groups, and the cable is Since it is only necessary to apply a voltage lower than the operating voltage, the problem of minute discharge pulses occurring within the cable is alleviated, and it is possible to easily obtain a device that can be used even in a high-temperature environment.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing a conventional proportional counter tube, Fig. 2 is a characteristic diagram showing the relationship between the frequency of minute discharge pulses generated in the cable and the applied voltage, and Fig. 8 is an embodiment of the present invention. Figure 4 t± is a schematic diagram showing a proportional counter according to another embodiment of the present invention. In the figure, (1) 11 anodes, (2) I cathodes, (3
) is the ionizing gas, (4) is the case, (6aX6b) is the coaxial cable, (7a) (7b) (conductor), (9a
) (9b) is an outer shield conductor. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Makoto Kuzuno - Figure 1 Figure 2 Figure 3 oyb Figure 4 Procedural amendment (voluntary) 1. Display of the incident Special request in 1973! -115965 No. 2
, Title of the invention Proportional counter 3, Relationship to the case of the person making the amendment Patent applicant address 2-2-3 Marunouchi, Chiyoda-ku, Tokyo Name (601) Mitsubishi Electric Corporation Representative Hitachi Katayama 4; Agent Address: 2-3-5, Maruno-Jiju-chome, Chiyoda-ku, Tokyo, Column 6 of Detailed Description of the Invention in the Specification Subject to Amendment, Contents of Amendment (1) " Correct "discharge pulse" to "discharge pulse". that's all

Claims (1)

[Claims] (1) A linear anode, a cathode that is electrically insulated from the anode and arranged to contain the anode, an ionizing gas sealed in the space between the cathode and the anode, and a cathode that houses the cathode and the anode. It has a case electrically insulated from the pole, and two coaxial cables attached to the case, one center conductor of the coaxial group is electrically connected to the anode, and the other center conductor is electrically connected to the cathode. , the outer shield conductors of the two coaxial cables are electrically connected to the case, a voltage on the positive side with respect to the case is applied to the anode, and a voltage on the negative side with respect to the case is applied to the cathode. A proportional counter to which voltage is applied.