JPH0640974U - Radiation measuring instrument for learning materials - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a radiation measuring instrument for learning materials, which is easy to understand the operation principle and circuit and is convenient to carry. [Constitution] G stored in a transparent case with holes on the side
A radiation measuring instrument for learning materials, comprising a M tube, a printed circuit board having an electronic circuit, an operation switch and a battery,
The M tube is attached to the transparent case so that it fits into the hole; the operation switch is attached to the transparent case; the operation switch and the printed circuit board are connected by a detachable connector; The measuring instrument according to claim 1, which has a counting and integrating function for measuring a low level air dose equivalent rate.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a radiation measuring instrument used as a learning material for learning the operation principle and circuits.

With the radiation measuring device of the present invention, measurement of air dose equivalent rate by natural radiation and γ-ray standard radiation source indoors and outdoors, measurement of radioactivity of geological radioactive mineral specimens, using standard radiation source It is possible to perform the maximum energy measurement of β-rays and the mass-permeation measurement experiment of β-rays and γ-rays, and to learn the characteristics of radiation.

[0003]

[Prior art]

 In high schools and universities and in various radiation workshops, we use GM radiation counters and GM radiation survey meters for disaster prevention management as practical training materials.

The structure of these commercial radiation counters is divided into a GM tube (probe) and a main body, both of which are connected by a signal cable, and both are housed in a metal case. The power source uses several dry batteries of AC100V or a single or a single shape.

These commercial-use radiation counters have complicated electric circuits for use as learning materials, and are too sophisticated and expensive. Moreover, the structure is not such that the internal structure can be easily observed. Furthermore, since it is divided into a GM tube (probe) and a main body and is housed in a metal case, it is large in shape and inconvenient for carrying. In particular, the one using AC100V as a power source is not suitable for outdoor measurement. In addition, in the case of a radiation meter with a pointer meter display type, when measuring the air dose equivalent rate due to natural radiation, the indicated value of the pointer fluctuates greatly due to statistical fluctuations and is difficult to read.

[0006]

[Problems to be solved by the device]

 In view of the above problems, it is an object of the present invention to provide a radiation measuring instrument for learning teaching materials, in which the operation principle and circuit can be easily understood and which is convenient to carry.

[0007]

[Means for Solving the Problems]

 In order to solve the above problems, according to the present invention, there is provided a radiation measuring instrument for learning teaching material, which comprises a GM tube housed in a transparent case having a hole on a side surface, a printed circuit board having an electronic circuit, an operation switch and a battery. The GM tube is mounted in a transparent case so that it fits into the hole; the operation switch is installed in the transparent case; the operation switch and the printed circuit board are connected by a detachable connector; and an electronic circuit Is provided with a counting and integrating function for measuring a low level of ambient dose equivalent rate due to natural radiation.

In the radiation measuring instrument of the present invention, since the GM tube and other components are housed in a transparent case, the internal structure is very easy to observe, and it is extremely suitable for learning teaching materials. . For the transparent case, a plastic material such as acrylic resin, which is relatively strong and lightweight, is suitable.

In the present invention, the GM tube does not take the form of a probe separate from the main body, but is integrated with the main body. There is a hole on the side surface of the transparent case, and the GM tube is attached to the transparent case so as to fit into the hole. As a result, β-rays are not absorbed by the transparent case and are not attenuated, so that the counting efficiency can be improved. The holes may be provided with a protective mesh to prevent damage to the GM tube. Preferably, the GM tube is arranged on a printed circuit board.

An operation switch for turning on / off the power supply is mounted on a transparent case and is easy to operate. Other switches that are not necessary for operation are preferably mounted on the printed circuit board.

The operation switch and the printed circuit board are connected by a removable connector. This makes it easy to assemble and disassemble the components, facilitates understanding of the operation principle and circuit, and makes it possible to distribute the kit as a kit, which is extremely suitable as a learning material.

The necessary electronic circuits are arranged on the printed circuit board. A small GM tube is used to count and integrate radiation pulses in order to measure low-level air dose equivalent rate due to natural radiation, and the integration of counting is performed by a timer circuit for 10 minutes or 1 minute. Minimize changes in measured values due to fluctuations.

In addition to this, in order to reduce the size and cost, and to enable the use of a small battery for a long time, the electronic circuit has only the minimum necessary functions as a learning material, Aim to simplify the circuit. For example, a CMOS integrated circuit or a liquid crystal display element is used as a part to be used to reduce the current consumption.

Hereinafter, the present invention will be described in more detail by way of examples.

[0015]

【Example】

 A radiation measuring instrument for learning materials having the appearance shown in FIG. 1 was produced. A block diagram of the electronic circuit of this radiation measuring instrument is shown in FIG. This electronic circuit has a counting integration function of 10 minutes or 1 minute for the measurement of low level air dose equivalent rate. Further, this radiation measuring instrument is composed of a GM tube housed in a transparent case having a hole on the side surface, a printed circuit board having the electronic circuit, an operation switch and a battery.

As a result of miniaturization, the radiation measuring instrument according to the present embodiment has a size of W82 mm-L147 mm-H32 mm and a weight of about 200 g.

The GM tube used was an end window type (Ne-halogen gas), and the external dimensions were 15 mmφ and the length was 50 mm. The operating voltage was 400 to 600V.

In order to efficiently measure β-rays, a hole having a shape equal to the outer shape of the GM tube was opened on the side surface of the transparent case. Then, a GM tube was attached so as to fit into the hole. A protective net is attached to the hole to protect the end window of the GM tube.

By making holes in the transparent case facing the end window of the GM tube, β rays could be efficiently counted. For comparison, when β rays were measured without making holes in the transparent case, 60% or more of ⁹⁰ Sr and 90% or more of ¹⁴⁷ Pm were absorbed by the transparent case.

The GM radiation counter of this embodiment has three switches, and the operation switches SW-1 and SW-2 are mounted in a transparent case, and SW-3 is mounted on a printed circuit board in the transparent case. Has been done.

SW-1 and SW-2 are toggle switches, and SW-1 serves both to select the counting time and to turn the power on / off. The power is turned off by making the switch neutral. Becomes

SW-2 controls the flip-flop (F / F) to start and stop the counting operation. At the start of counting, the counter is reset by the edge trigger of the F / F output and the previous counted value is cleared.

The SW-3 has switches a and b. A can be used to select ON / OFF of the counting sound at the time of counting, and b can be used to select ON / OFF of the timer (1 minute or 10 minutes). it can. When b is turned off and timer off is selected, the manual counting operation is stopped and the counting time becomes arbitrary.

When the count value (maximum 19999) is exceeded during measurement, the F / F is set by the carry signal from the counter, and the count display is displayed on the display.

A liquid crystal display was used as the display. Although this liquid crystal display is mounted on the printed circuit board, the counting display can be seen through the transparent case.

A 9V (006P) dry battery was used as a power source. As a result of the low current consumption, the consumption current is about 1.5 mA, and despite using a small battery, it can be used for a time equal to or longer than the conventional commercial radiation counter. did it.

Using the radiation measuring instrument of this example, normal indoor natural radiation was measured. As a result, the total of 10 minutes was about 150 counts, and the statistical variation of the measured value was 10% or less, and the measurement of the air dose equivalent rate by natural radiation was sufficiently performed.

Next, natural radiation and daughter nuclides of radon and thoron (suctioned on filter paper for 1 hour with a dust sampler in an unventilated laboratory) were selected as measurement targets, and radiation was measured. The results are shown in Tables 1 and 2 below.

[0029]

[Table 1]

[Table 2]

[0030]

According to the radiation measuring instrument for learning material of the present invention, it is possible to easily measure the air dose equivalent rate due to natural radiation indoors and outdoors, which was conventionally measured using the ionization chamber or the scintillation detector. Deepen your understanding of natural radiation. Moreover, since the components are housed in a transparent case, the internal structure is well understood, which is suitable for understanding the operation principle and circuit. In addition, since there is a hole in the transparent case facing the end window of the GM tube, there is no β-ray attenuation and the counting efficiency is high. Furthermore, because of the smaller size and lower prices, it will be possible to provide learning materials to all participants, improving learning efficiency. In addition, by simplifying the structure and circuit, it can be used as a learning material in the form of an assembly kit, and by assembling it, understanding of the operation principle and circuit is promoted.

[Brief description of drawings]

FIG. 1 is an external structural view of a radiation measuring instrument for learning material of the present invention.

FIG. 2 is a block diagram of an electronic circuit of the radiation measuring instrument for learning material of the present invention.

Claims (1)

[Scope of utility model registration request] 1. A radiation measuring instrument for learning material comprising a GM tube housed in a transparent case having a hole on a side surface, a printed circuit board having an electronic circuit, an operation switch and a battery, wherein the GM tube is fitted into the hole. The operation switch is attached to the transparent case; the operation switch and the printed circuit board are connected by a detachable connector; and the electronic circuit has a low level space dose equivalent due to natural radiation. The measuring instrument, having a counting and integrating function for measuring a rate.