JPH09304538A - Radiation detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To discriminate the characteristic of a radiation, e.g. the kind of the radiation, on the basis of its signal sound in a radiation detector which generates the signal sound when the radiation is detected. SOLUTION: The light emission of a scintillator 12a for α-ray detection and that of a scintillator 12b for β-ray detection are transduced into electrical detection signals by a photomultiplier tube(PMT) 14. In a waveform discrimination circuit 16, a detection signal which is output from the photomultipler tube 14 is discriminated into an α-ray detection signal and a β-ray detection signal on the basis of the feature of its waveform. The α-ray detection signal is input to a sound circuit 26a, and the β-ray detection signal is input to a sound circuit 26b. The respective sound circuits 26a, 26b generate signals used to generate signal sounds whose timbre is different from each other. Loudspeakers 27a, 27b are driven by the signals which are output by the respective sound circuits 26a, 26b. By this constitution, a signal sound is output at a timbre which is different according to a case in which α-rays are detected and to a case in which β-rays are detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation detecting device, and more particularly to a detection result output mechanism of the radiation detecting device.

[0002]

2. Description of the Related Art In some radiation detection devices such as survey meters, in addition to visually displaying the measurement result (eg, count rate) obtained by signal processing the detection signal in analog or digital form, Some have a function of directly driving a sound source such as an electronic buzzer and informing the detection status by sound.

[0003]

Basically, the sound output function of the conventional radiation detecting apparatus is only a simple one of outputting a detection sound when radiation is detected, as represented by a GM counter. . The radiation detection device is capable of discriminating the detected radiation line type (α-ray or β-ray) like the device of Japanese Patent Publication No. 6-27849 by the applicant, or the radiation energy by wave height analysis of the detection signal. There are some which can discriminate the characteristics of the radiation, such as those which can discriminate, but none of which can output the discriminated characteristics of the radiation by voice.

The present invention has been made to solve such a problem, and it is an object of the present invention to provide a new type of radiation detecting apparatus capable of audibly identifying the characteristics of the detected radiation. To aim.

[0005]

In order to achieve the above-mentioned object, the radiation detecting apparatus according to the present invention, when detecting radiation, outputs a detection signal having a waveform reflecting a predetermined characteristic of the detected radiation. A detection unit, a signal classification unit that classifies the detection signal based on the characteristics of the waveform, and a voice output unit that receives the classification result of the signal classification unit and outputs signal sounds of different tones according to the classification result. Have and.

In this structure, when the radiation enters, the detection unit outputs a detection signal having a waveform according to the characteristics of the radiation, for example, the line type and energy. The signal classification unit receives the detection signal and classifies the detection signal based on the characteristics of the waveform. Here, the waveform characteristics include, for example, pulse width and pulse wave height. For example, α rays and β rays can be distinguished by the steepness (that is, pulse width) of the pulse waveform of the detection signal, and the energy of radiation can be determined by the pulse wave height of the detection signal. Then, the audio output unit outputs a signal sound of a tone color according to the classification result of the signal classification unit. With such a configuration, the radioactivity detection device according to the present invention can output a signal sound of a tone color according to the characteristics of the radiation each time the radiation is detected. That is, in this configuration, the audio output unit can output signal sounds of a plurality of tones, and the characteristics of the detected radiation can be identified by properly using the tones. In the present specification, the term timbre is widely used as a concept that expresses the auditory distinctiveness of sounds, and different timbre means that the sounds can be distinguished from each other due to differences in the frequency and overtone structure of the sounds. And

Further, in a preferred aspect of the present invention, the detection section is capable of detecting α-rays and β-rays, and detection signals of different waveforms are detected when α-rays are detected and when β-rays are detected. And the signal classification unit classifies the detection signal into an α-ray detection signal and a β-ray detection signal based on the waveform, and the audio output unit receives the α-ray detection signal from the signal classification unit. It is characterized in that signal sounds of different timbres are output depending on whether it is received or a β-ray detection signal is received.

According to this structure, it is possible to distinguish between the case where the α ray is detected and the case where the β ray is detected by the timbre.

Further, when the present invention is applied to the surface contamination detection, a sound having a higher audibility than the signal sound when the β ray is detected is used as the signal sound when the sound output section detects the α ray. It is also effective to have a configuration. According to this configuration, by making the α-ray detection signal sound that should not be missed more easily heard, it is possible to reduce the possibility that the α-ray detection signal sound is buried in the β-ray detection signal sound. it can.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A preferred embodiment of a radiation detecting apparatus according to the present invention will be described below by taking a survey meter for detecting surface contamination as an example.

FIG. 1 schematically shows the structure of the survey meter of this embodiment. As shown in FIG. 1, the survey meter is composed of a probe unit 10 for detecting radiation and a main body unit 20 including a power source, a signal processing circuit, etc., and a measurer holds the probe unit 10 with one hand and 10 is brought close to the measurement point to detect surface contamination.

The probe unit 10 has two plate-shaped scintillators as radiation detectors. That is, α
ZnS (Ag) scintillator 12a for detecting rays and plastic scintillator 12b for detecting β rays (and γ rays)
It is.

The light emitted from the scintillator 12a or 12b due to the incidence of radiation is converted into an electrical detection signal by the photomultiplier tube (PMT) 14. The waveform discriminating circuit 16 discriminates the detection signal output from the photomultiplier tube 14 into an α-ray detection signal and a β-ray detection signal according to the characteristics of the waveform.

FIG. 2 is a block diagram showing the internal structure of the waveform discrimination circuit 16. Since there is a large difference in the decay time of light emission between the ZnS (Ag) scintillator and the plastic scintillator (the former is several microseconds, the latter is several nanoseconds), this embodiment detects α rays and β rays. A comparatively remarkable difference appears in the pulse width (or pulse decay) of the detection signal between the case and the case. The waveform discrimination circuit 16 of the present embodiment is
The difference between the pulse widths of the detection signals is used to discriminate between α rays and β rays.

As shown in FIG. 2, the detection signal output from the photomultiplier tube 14 is first amplified by the preamplifier 161. The signal output from the preamplifier 161 is α
The first wave height discrimination circuit 16 via the line separation filter 162.
Input to 3. The α-ray separation filter 162 is an integration filter having a time constant of about 2 μsec, and the β-ray detection signal is significantly attenuated by the α-ray separation filter 162. Therefore, the α-ray detection signal can be obtained by discriminating the pulse signal having a predetermined wave height or more by the first wave height discriminating circuit 163. Further, the second wave height discrimination circuit 164 is
The output signal of the preamplifier 161 is wave height discriminated to remove noise. As a result, from the second wave height discrimination circuit 164,
Detection signals of both α rays and β rays are output. Gate circuit 1
65 subtracts the α-ray detection signal obtained by the first wave height discrimination circuit from the output signal of the second wave height discrimination circuit 164 to extract the β-ray detection signal. Note that FIG.
The configuration shown in is the same as that disclosed in Japanese Patent Publication No. 6-27849.

The α-ray detection signal and β-ray detection signal thus obtained are input to the main unit 20. In the main body unit 20, the input signal is input to the rate meter 21, the scaler 23, and the sound circuits 26a and 26b, respectively.

The rate meter 21 obtains the average count rate of β-ray detection signals. The average count rate is displayed on the display unit 24 in an analog manner. Further, the scaler 23 counts one of the α ray detection signal and the β ray detection signal selected by the switch 22. The counting result is digitally displayed on the liquid crystal display 25. It should be noted that the reason why the counting rate measurement is limited to β rays only in the present embodiment is that the counting rate display is generally used for identifying a contaminated portion, but the fact that α rays have been detected causes immediate contamination. This is because the counting rate hardly poses a problem in specifying the contaminated part of α ray.

In this embodiment, a separate audio output mechanism is provided for each of the α ray detection signal and the β ray detection signal. That is, the main body unit 20 includes the sound circuit 26a for the α ray detection signal and the speaker 27a,
Sound circuit 26b and speaker 27 for β-ray detection signal
b. Each sound circuit 26a and 26b
Generates a predetermined drive signal when the detection signal is input, and drives the speakers 27a and 27b. As a result, signal sounds with different timbres are output from the speakers 27a and 27b. In the present embodiment, for example, 3 kHz is detected when α rays are detected, and 2 kHz is detected when β rays are detected.
The z signal sound is output. It should be noted that the timbre here means not only the frequency but also the sound quality peculiar to each sound due to the characteristics of the composition of the harmonic components.

In the control of surface contamination, the α ray has a stricter control standard than the β ray, and it is necessary to suspect the contamination if even one is detected. On the other hand, since β rays have a background, a certain amount is always detected. For this reason,
The signal sound when the α ray is detected may be buried in the signal sound when the β ray is detected, and it may be difficult to determine the α ray detection. On the other hand, for example, if the signal sound when the α ray is detected is a sound that is more audible than the signal sound when the β ray is detected (in other words, a sound that is often heard), the measurer can make the α ray. Can be detected more clearly.

As described above, the survey meter of the present embodiment outputs a signal sound of different tone color depending on whether the radiation is an α ray or a β ray each time the radiation is detected. The person can know which line type is detected by the tone color of the signal sound.

In the above embodiment, the line type of the radiation can be identified by the tone color of the signal tone, but the present invention can of course represent the energy of the radiation by the tone color. The configuration of the apparatus in this case may be, for example, a configuration in which the detection signal is energy-analyzed by a multi-channel wave height analyzer, and signal tones of different tones are output for each energy of the detection signal.

In the above description, a survey meter for detecting surface contamination was taken as an example, but it goes without saying that the present invention can be applied to radiation detection apparatuses in general other than this example.

[0023]

As described above, according to the present invention, when radiation is detected, a signal tone having a tone color corresponding to the characteristic of the radiation is output, so that the characteristic of the detected radiation can be identified by the tone color.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of a radiation detection apparatus according to the present invention.

FIG. 2 is a block diagram showing an internal configuration of a waveform discrimination circuit.

[Explanation of symbols]

10 probe unit, 12a ZnS (Ag) scintillator, 12b plastic scintillator, 14
Photomultiplier tube (PMT), 16 Waveform discrimination circuit, 20
Main unit, 21 rate meter, 22 switch,
23 scaler, 24 display section, 25 liquid crystal display, 2
6a, 26b sound circuit, 27a, 27b speaker.

Claims (3)

[Claims] 1. A detection unit that outputs a detection signal having a waveform that reflects a predetermined characteristic of the detected radiation when detecting the radiation, and a signal classification unit that classifies the detection signal based on the characteristics of the waveform. A radiation detection device, comprising: a sound output unit that receives a classification result of the signal classification unit and outputs signal sounds of different tones according to the classification result. 2. The radiation detecting apparatus according to claim 1, wherein the detection unit is capable of detecting α-rays and β-rays, and has different waveforms when α-rays are detected and when β-rays are detected. Outputting a detection signal, the signal classification unit separates the detection signal into an α-ray detection signal and a β-ray detection signal based on the waveform thereof, and the audio output unit includes an α-ray detection signal from the signal classification unit. A radiation detecting apparatus, which outputs a signal sound of a different tone color when receiving a β-ray detection signal and when receiving a β-ray detection signal. 3. The radiation detecting apparatus according to claim 2, which is used for surface contamination detection, wherein the voice output unit outputs a β signal to a signal sound when an α ray is detected.
A radiation detecting apparatus characterized by using a sound which is more audible than a signal sound when a line is detected.