JPH0432144A - Variable characteristic ionization chamber - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention] [Industrial Application Field] The present invention relates to a variable characteristic ionization chamber that can be used to measure air dose in facilities that use radioactive materials.

[Conventional technology]

Conventionally, an ionization chamber is known as a device that measures the intensity of radiation by measuring the amount of ions generated in ionized gas due to the incidence of radiation.

This ionization chamber is composed of a hollow cylindrical electrode (cathode) and an electrode (anode) placed in the center, and the space of the picture electrode is filled with ionized gas such as argon or nitrogen. An appropriate voltage is applied between both electrodes, and ionized ions generated in the ionized gas due to the incidence of radiation are collected by the electrodes, and the amount of electricity due to the ionized ions is detected.

By the way, the detection sensitivity and sensitivity characteristics of the above-mentioned ionization chamber are determined by the composition of the ionized gas sealed in it, so when the required detection sensitivity and sensitivity characteristics change, it is necessary to find an ionized gas with a composition that satisfies such sensitivity. It was necessary to prepare a pre-filled ionization chamber.

Further, as such an ionization chamber is continuously used, the detection sensitivity and sensitivity characteristics change, so it is necessary to correct the measured value in accordance with the deterioration of the detection sensitivity.

[Problem to be solved by the invention]

Therefore, conventional ionization chambers have fixed sensitivity and sensitivity characteristics, and cannot be used when the required sensitivity characteristics change, and cannot cope with changes over time.

The present invention has been made in view of the above-mentioned circumstances, and is a variable characteristic ionization method that can freely change the sensitivity and sensitivity characteristics and maintain the sensitivity and sensitivity characteristics at desired values over a long period of time. The purpose is to provide a box.

[Structure of the Invention [Means for Solving the Problems] In order to solve the above problems, the present invention includes an ionization chamber body in which ionized gas is sealed, and ionization gases of different components are supplied to each of the ionization chamber bodies. A plurality of gas supply sources, an on-off valve provided in a gas supply path that guides the ionized gas from each of these gas supply sources to the ionization chamber body, and a plurality of gas supply sources sealed in the ionization chamber body according to the required sensitivity or sensitivity characteristics. The device is configured to include means for determining the component ratio of the ionized gas, and means for controlling the on-off valve so as to achieve the component ratio determined by this means.

[Effect]

By taking the above measures, the present invention calculates the component ratio of the ionized gas that realizes the sensitivity or sensitivity characteristics according to the required sensitivity or sensitivity characteristics, and then calculates the component ratio of the ionized gas that achieves the required sensitivity or sensitivity characteristics. Each on-off valve is controlled, and each different ionized gas flows into the ionization chamber main body through the gas supply path. As a result, ionized gas is filled with a component ratio that achieves the sensitivity or sensitivity characteristics required for the ionization chamber body. Therefore, the composition of the ionized gas can be changed freely, and the sensitivity and sensitivity characteristics can be changed freely.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a diagram showing the configuration of a variable characteristic ionization chamber which is an embodiment of the present invention. The ionization chamber of this embodiment has a plurality of gas cylinders 3-3 connected to the ionization chamber main body 1 via piping 2 serving as a gas supply path.
1 to B-n are connected. Each gas cylinder 3 is filled with ionized gas having a different composition, and each ejection port is provided with an electromagnetic valve 4 for controlling the amount of the gas discharged. Piping 2 whose one end is connected to the ionization chamber body 1
is connected to the exhaust pump 6 via the exhaust solenoid valve 5,
Another solenoid valve 7 is provided in a portion communicating with the ionization chamber body 1. Further, the piping 2 is provided with a pressure gauge 8 for measuring the pressure of the ionized gas flowing into the ionization chamber body 1. The solenoid valves 4, 5.7 and the exhaust pump 6 are controlled to open and close according to commands from the computer 8. The computer 8 stores data such as the component ratio and gas pressure of ionized gas that realizes various sensitivities and sensitivity characteristics in its database, and when a predetermined sensitivity and sensitivity characteristics are required, the computer 8 generates ionized gas that meets the requirements. The gas component ratio and gas pressure are read from the database, and each electromagnetic valve 4 of an arbitrary gas cylinder 3 is adjusted to match the read component ratio and gas pressure.
It has a function of controlling opening and closing based on the pressure measured by the pressure gauge 8.

The quantity of electricity due to ionized ions produced by the incidence of radiation on the ionization chamber body 1 is measured by a measuring device 9, and the measured value is input into the computer 8. Furthermore, computer 8
has a function of analyzing the sensitivity and sensitivity characteristics of the ionized gas sealed in the ionization chamber body 1 based on the measured values input from the measuring device 9.

Next, the operation of this embodiment configured in this manner will be explained.

FIG. 2 shows the change in sensitivity characteristics corresponding to the composition ratio of the ionized gas. As shown in the figure, various sensitivity characteristics can be obtained by appropriately combining the composition ratio of the ionized gas and the pressure of each gas. In this embodiment, various sensitivity characteristics as shown in FIG. 2, gas component ratios and gas pressures corresponding to the characteristics are stored in advance in the database of the computer 8.

When the measurer instructs the computer 8 about the desired sensitivity and sensitivity characteristics, the computer 8 reads out the composition ratio and gas pressure of the ionized gas that satisfy the conditions from its database, and controls the electromagnetic valve of the gas cylinder 3 containing the corresponding components. Open 4. The gas pressure of the gas flowing into the ionization chamber 1 from the gas cylinder 3 is detected by a pressure gauge 8 and transmitted to the computer 8.

The computer 8 gives a command to the corresponding electromagnetic valve 3 to control it so that the read gas pressure is achieved. In this way,
Gases of each component are sealed in the ionization chamber body 1. If the ionization chamber main body 1 is filled with ionized gas, before starting the above operation, give an opening command to the solenoid valves 5 and 7 to open them, and then operate the exhaust pump 6 to remove ionization. The ionized gas in the box body 1 is exhausted.

When checking the sensitivity and sensitivity characteristics of the ionized gas sealed in the above manner, a check source is used to irradiate radiation with different energies.

The intensity of the irradiated radiation is measured by a measuring device 9 and sent to the computer 8. The computer 8 analyzes the input radiation measurement values and determines whether the set sensitivity characteristics are met. If the set sensitivity characteristics are not met, a calibration value is calculated, and a gas having the calculated composition is caused to flow into the ionization chamber main body 1 from the corresponding gas cylinder 3.

Furthermore, since the sensitivity to ionized gas deteriorates with long-term use, it is desirable to periodically carry out a sensitivity calibration test using the above-mentioned check source.

As described above, according to this embodiment, the plurality of gas cylinders 3-1 to
In addition to preparing ionized gases with different compositions in advance for 3-n, the composition ratios and gas pressures of ionized gases corresponding to various sensitivity characteristics are stored in the database of the computer 8, and the required sensitivity and sensitivity characteristics are adjusted. The composition ratio and gas pressure of the corresponding ionized gas are read out, and gases with the corresponding composition are supplied from the plurality of gas cylinders 3 to the ionization chamber main body 1 so that the read values are obtained, so that the sensitivity and sensitivity of the ionization chamber are Characteristics can be changed very easily and freely.

Therefore, even if the standard regarding the sensitivity of the ionization chamber changes, for example, it can be dealt with promptly without replacing the device. In addition, since the sensitivity can be freely changed, it is an extremely effective means for applications that require evaluation of radiation of a specific energy in radiation aggregation, modification by radiation, etc. in which the effects of specific radiation are considered.

Furthermore, even if the sensitivity to ionized gas deteriorates due to long-term use, the sensitivity can be corrected very easily by a sensitivity calibration test using a check source, and the same sensitivity can be maintained for a long period of time.

In the above embodiment, the database is used to determine the composition ratio and gas pressure of the ionized gas that realizes the required sensitivity characteristics, but they may be calculated each time by the computer 8.

Further, in the above embodiment, an example was shown in which each gas cylinder 3 was prepared with a gas having a single composition, but any gas cylinder 3 may be filled with a mixed gas.

[Effects of the Invention] As detailed above, according to the present invention, the characteristic variable type is capable of freely changing the sensitivity and sensitivity characteristics and maintaining the sensitivity and sensitivity characteristics at desired values over a long period of time. We can provide ionization chambers.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a diagram for explaining changes in sensitivity characteristics due to combinations of composition ratio of ionized gas and gas pressure. DESCRIPTION OF SYMBOLS 1... Ionization chamber body, 2... Piping, 3... Gas cylinder, 4.7... Solenoid valve, 5... Exhaust solenoid valve, 6...
...exhaust pump, 8...computer, 9...measuring instrument. Applicant's representative Patent attorney Takehiko Suzue

Claims (1)

[Claims] An ionization chamber body in which an ionized gas is sealed, a plurality of gas supply sources each supplying ionized gases of different components to the ionization chamber body, and a gas supply path that guides the ionized gas from each of these gas supply sources to the ionization chamber body. a means for determining the component ratio of the ionized gas sealed in the ionization chamber body according to the required sensitivity or sensitivity characteristics; An ionization chamber with variable characteristics characterized by comprising means for controlling a valve.