JPH0587935A - Radiation measuring apparatus - Google Patents

Abstract

PURPOSE:To measure two kinds of element radiations composing a compound radiation field once without extra time and labor and at a radiation detection sensitivity depending on no radiation impinging position on a radiation impinging surface. CONSTITUTION:A first scintillator 9, a first light filter 14 and a second scintillator 10 are laminated sequentially and, moreover, a first photoelectric converter 11 is mounted on the second scintillator 10 through a second light filter 16. A second photoelectric converter 12 is mounted on the second scintillator 10 through or not through a third light filter 17 and output signals of both the photoelectric converters 11 and 12 are inputted into one non-simultaneous circuit 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation measuring apparatus using a scintillation detector, and more particularly, to measuring each elemental radiation in a short time and with high accuracy in a composite radiation field consisting of two types of elemental radiation. The measuring device that can be used.

[0002]

2. Description of the Related Art FIG. 5 shows the construction of a conventional radiation measuring apparatus 4 for measuring both elemental radiations 1 and 2 in a field G of a composite radiation 3 consisting of β-rays 1 and γ-rays 2 as elemental radiations. In the figure, 5 is a plate-like β-ray absorber made of aluminum, acrylic resin, or the like, and 6 is arranged such that the radiation incident surface 6a is close to and faces one surface 5a of the absorber 5 and the incident surface. A radiation detector adapted to output a detection signal 6b corresponding to the radiation incident from 6a, wherein the measuring device 4 is composed of this detector 6 and an absorber 5, and in this case the absorber 5 is It is removable. Since the measuring device 4 is configured in this way, when the other surface 5b of the absorber 5 is opposed to the radiation field G, the γ ray 2 can be measured by the detection signal 6b, and the surface 5b is opposed to the field G. Since the composite radiation 3 can be measured by the signal 6b when the absorber 5 is removed in this state, the measurement related to the β-ray 1 can be performed from the measurement results, and eventually the measurement device 4 can measure both. The radiations 1 and 2 can be measured.
FIG. 6 shows a conventional radiation measuring apparatus 7 different from the measuring apparatus 4, which measures both radiations 1 and 2 in a radiation field G.
It is a block diagram of. In FIG. 6, reference numeral 8 is a first scintillator formed by laminating a thin plate-shaped first scintillator 9, a β-ray absorber 5 and a thick plate-shaped second scintillator 10 as shown in the drawing. The scintillation light emitting portion whose 9 side is opposed to the radiation field G, and 11 is arranged so that the light receiving surface 11a is brought into contact with the side surface of the scintillator 9 to receive the scintillation light generated in the scintillator 9. 1 photoelectric converter, 12 is a second photoelectric converter arranged so that the light receiving surface 12a is brought into contact with the side surface of the scintillator 10 to receive scintillation light generated in the scintillator 10, and 13 is a first input Terminal 13
a and the second input terminal 13b are provided, and the terminal 13b
If a pulse is input to the terminal 13a when no pulse is input to the terminal 13, a pulse signal 13c corresponding to this pulse is output, and even if a pulse is input to the terminal 13a, the terminal 1
This is a non-simultaneous circuit that does not output the signal 13c when a pulse is input to 3b. Then, the measuring device 7
Is a device including the above-mentioned parts, and here, the scintillator 9
Has a thickness of about 0.1 mm to 10 mm that sufficiently absorbs the β ray 1 of the two radiations 1 and 2 incident from the radiation field G and hardly absorbs the γ ray 2, and the scintillator 10 has It is formed to a thickness that can sufficiently absorb the γ-ray 2. Thus, in this case, the absorber 5 may be omitted if the scintillator 9 is formed to have a thickness that sufficiently absorbs the β-ray 1. Since the radiation measurement device 7 is configured as described above, both radiations 1
Pulse train signal 11b based on the scintillation light generated in scintillator 9 by
Pulse train signal 1 based on the scintillation light output from the scintillator 10 by the γ-ray 2
As a result of 2b being output from the photoelectric converter 12, the pulse 13
The pulse train signal 13d consisting of c is output from the non-simultaneous circuit 13 as a signal corresponding to the β-ray 1. Consequently, in the case of this measuring device 7, the pulse train signals 13d, 12
It is clear that the doses of both radiations 1 and 2 can be measured at one time by counting each pulse in b.

[0003]

In the above measuring device 4, in order to measure both radiations 1 and 2, the measuring operation is performed twice, as described above, with and without the absorber 5 attached. Therefore, this device 4 has a problem in that it takes time and effort to discriminate between the radiations 1 and 2. However, on the contrary, since the radiation measuring apparatus 7 is configured as described above, both radiations 1,
Although there is an advantage that the measurement of No. 2 is not troublesome, on the other hand, in this device 7, since the area of the portion of the scintillator 9 in contact with the photoelectric conversion light receiving surface 11a is small for the above-mentioned reason, the utilization efficiency of the light receiving surface 11a is high. There is a problem that it is bad,
Further, in the case of this device 7, the scintillation light generated in the scintillators 9 and 10 is attenuated according to the distance from the light generation position to the converter light receiving surfaces 11a and 12a and reaches the light receiving surfaces 11a and 12a. Moreover, in this case, since the light-receiving surfaces 11a and 12a are brought into contact with the respective side surfaces of the scintillators 9 and 10, the measuring device 7 is provided with the radiations 1 and 2.
There is also a problem that the detection sensitivity to the scintillation light differs depending on the position of the scintillator 9 on which is incident, in other words, the radiation detection sensitivity distribution on the surface 9a of the scintillator 9 facing the radiation field G is not uniform. An object of the present invention is to provide a radiation measuring apparatus capable of measuring two types of element radiations that form a composite radiation field by using two plate-shaped scintillators and two photoelectric converters at one time.
The scintillation light is incident on each light receiving surface of both photoelectric converters from one surface of one scintillator so that the utilization efficiency of each of the both light receiving surfaces is good and the radiation detection sensitivity distribution on the radiation incident surface of the scintillator is The purpose is to obtain a substantially uniform radiation measuring device.

[0004]

In order to achieve the above object, according to the present invention, 1) a first scintillator and a first scintillator, each of which is formed in a plate shape.
A scintillation light emitting portion obtained by sequentially stacking an optical filter and a second scintillator, and scintillation light as a surface of the second scintillator on the side not contacting the first optical filter. A first photoelectric converter that receives light through a second optical filter that is in contact with the emission surface, the second optical filter, and third light that is in contact with the scintillation light on the scintillation light emission surface of the second scintillator. A second photoelectric converter that receives light through a filter, the third optical filter, and a non-simultaneous circuit to which the output signals of the both photoelectric converters are input are provided. 2 From the output signal of the photoelectric converter, the scintillation is performed from the surface of the first scintillator that is not in contact with the first optical filter. A radiation measuring apparatus for measuring two types of radiation incident on a light emitting part, wherein both the scintillators are made of the same material, and the first and second optical filters have the same light transmission characteristics. And the third optical filter is a bandpass optical filter that transmits light in a wavelength band different from the light transmission wavelength bands of the first and second optical filters, and the radiation measuring apparatus is configured as follows. 2) First scintillator, first plate-shaped scintillator
A scintillation light emitting portion obtained by sequentially stacking an optical filter and a second scintillator, and scintillation light as a surface of the second scintillator on the side not contacting the first optical filter. A first photoelectric converter that receives light through a second optical filter that is in contact with the emission surface, the second optical filter, and a second photoelectric converter that directly receives the scintillation light through the scintillation light emission surface. A non-simultaneous circuit to which the output signals of the both photoelectric converters are input, and the first optical filter of the first scintillator according to the output signal of the non-simultaneous circuit and the output signal of the first photoelectric converter. A radiation measuring device for measuring two types of radiation incident on the scintillation light emitting part from the surface not contacting the The both optical filters are bandpass optical filters having the same transmission characteristics, and the second scintillator emits the scintillation light in a wavelength band different from the light transmission wavelength band of the both optical filters when the radiation enters. 3) In the radiation measuring apparatus described in 1) above, both scintillators are made of barium fluoride (BaF ₂ ) and the light of the first and second optical filters is formed. Two different center wavelengths of the transmission wavelength band and the center wavelength of the light transmission wavelength band of the third optical filter in the spectral spectrum of the intensity of the scintillation light generated in the barium fluoride when the radiation is incident on the barium fluoride. The radiation measuring device is configured so as to correspond to each of the peak wavelengths, and 4) above 1) to 3). In the radiation measuring apparatus according to any one of the items 1, the radiation measuring apparatus is configured by using two kinds of radiation as β rays and γ rays.

[0005]

With the above construction, most of the scintillation light produced by one scintillator is based on one of the two radiations corresponding to this scintillator, in any of the radiation measuring devices. By setting the thickness of each scintillator so that most of the scintillation light produced by the other scintillator is based on the other of the two,
The doses of both radiations can be measured at once by the output signal of the non-simultaneous circuit and each output signal of the second or first photoelectric converter. The light receiving surface of the converter is directly opposed to the scintillation light emitting surface of the scintillation light emitting portion via each of the second and third optical filters or the light receiving surface of the second photoelectric converter is not provided via the third optical filter. Therefore, the distances from the scintillation light emitting position in the scintillation light emitting section to the light receiving surfaces of both photoelectric converters are almost uniform regardless of the radiation incident position in the radiation incident surface of the scintillation light emitting section. Therefore, the utilization efficiency of each of the light receiving surfaces is good, and the radiation detection sensitivity distribution on the radiation incident surface is almost uniform. So that the line measuring device is obtained.

[0006]

1 is a block diagram of an embodiment of the present invention. The difference from FIG. 6 in this figure is that a first optical filter 14 and both scintillators 9 and 10 in place of the β-ray absorber 5 in FIG. And the scintillation light emitting portion 15 corresponding to the above-mentioned scintillation light emitting portion 8 is configured, and the first photoelectric converter 1
1 receives the scintillation light generated in the scintillation light emitting section 15 as the surface of the scintillator 10 which is not in contact with the optical filter 14 through the second optical filter 16 which is in contact with the scintillation light emission surface 10a.
The light receiving surface 11a of the converter 11 is brought into contact with the filter 16 and the filter 16 is brought into contact with the surface 10a, and the second photoelectric converter 12 causes the scintillation light generated in the light emitting portion 15 to be applied to the surface 10a. So that light is received through the third optical filter 17 that is in contact with the light receiving surface 1 of the converter 12.
2a is brought into contact with the filter 17 and the filter 17 is brought into contact with the surface 10a. And then
In FIG. 1, both scintillators 9 and 10 are made of barium fluoride (BaF ₂ ), and the first and second optical filters 14 and 16 have the same band light transmission characteristics 18 shown in FIG. It is a bandpass optical filter,
Further, the third optical filter 17 is a bandpass optical filter having the band light transmission characteristic 19 shown in FIG. 2 over the light transmission wavelength band different from the light transmission wavelength band occupied by the characteristic 18, and here, the characteristic 18 , 19 have center wavelengths of 220 nm and 300 nm, respectively. Then, 20 in the figure is a spectral spectrum of the intensity of scintillation light generated in the barium fluoride when radiation is incident on the barium fluoride, and this spectrum 20 has the light wavelengths of 220 nm and 300 nm as shown in FIG. It is a bimodal spectrum having a peak at each of. Reference numeral 21 in FIG. 1 is a radiation measuring apparatus including the respective units shown in FIG. The radiation measuring device 21 is configured as described above, and in this case as well, since the scintillators 9 and 10 are each formed to have the same thickness as that of the measuring device 7,
Now, the radiation incident surface 9 as one surface 9a of the scintillator 9
The number of times each of the scintillation light emitted from each of the scintillators 9 and 10 within a predetermined time τ when the β-ray 1 is incident from a is set to Nβ1 and Nβ2, and the γ-ray 2 is incident from the incident surface 9a. Letting Nγ1 and Nγ2 be the number of times scintillation light generated in each of the scintillators 9 and 10 within τ, the pulse train signal 11b output from the converter 11 is (Nβ1 + Nβ2 + Nγ1 +
The pulse train signal 12b output from the converter 12 is a signal corresponding to (Nβ2 + Nγ2), and thus the pulse train signal 13d output from the non-simultaneous circuit 13 is a signal corresponding to (Nβ1 + Nγ1). .. Then, here, Nβ2 << Nγ2, Nβ1 >> N
Since it is clear from the configuration of the light emitting unit 15 that γ1 is obtained, according to this measuring device 21, the signals 13d and 1
With 2b, the doses of both radiations 1 and 2 can be measured at one time. Then, in this measuring device 21, as described above, the photoelectric converter light-receiving surface 11a is made to face the scintillation light emitting surface 10a through the filter 16 over the entire surface thereof and the photoelectric converter light-receiving surface 12a.
Is opposed to the surface 10a through the filter 17 over its entire surface, so that the distance from the light emitting position of the scintillation light in the light emitting unit 15 to the light receiving surfaces 11a and 12a does not depend on the radiation incident position on the radiation incident surface 9a. Therefore, the radiation measuring device 21 is a device in which the utilization efficiency of the light receiving surfaces 11a and 12a is high and the radiation detection sensitivity distribution on the radiation incident surface 9a is substantially uniform.

FIG. 3 is a block diagram of a radiation measuring apparatus 22 as another embodiment of the present invention different from the embodiment shown in FIG. 1, and 23, which is different from FIG. The second scintillator 23 corresponding to the two scintillator 10 has a thickness sufficient to absorb γ-rays 2 and is a thallium-activated cesium iodide CsI.
(Tl), and the spectral spectrum 24 of the intensity of the scintillation light generated in this CsI (Tl) is
As shown in FIG. 4, the unimodal spectrum exists in a wavelength band different from the optical wavelength band occupied by the above-mentioned band light transmission characteristic 18, and the light receiving surface 12 a of the photoelectric converter 12 is of the scintillator 23. Being brought into contact with the scintillation light emitting surface 23a as a surface not contacting the optical filter 14, and the first input terminal 13a of the non-simultaneous circuit 13.
The pulse train signal 12b output from the converter 12 is input to the second input terminal 13b of the circuit 13, and the pulse train signal 11b output from the converter 11 is input to the second input terminal 13b of the circuit 13. Then, in FIG. 3, 25 is both scintillators 9, 23.
A scintillation light emitting portion including a filter 14 and a filter 14. Since the radiation measuring device 22 is configured as described above, the signal 12b is (Nβ1 + Nβ) in this device 22.
2 + Nγ1 + Nγ2) corresponding to the signal 11
b becomes a signal corresponding to (Nβ1 + Nγ1), and therefore the pulse train signal 13d output from the circuit 13 is (N
The signal corresponds to β2 + Nγ2). Then, Nβ1 >> Nγ1 and Nβ2 << Nγ2 are the same as in the case of FIG.
With b and 13d, the doses of both radiations 1 and 2 can be measured at one time. And again, this device 22
Since the light receiving surfaces 11a and 12a of both photoelectric converters are opposed to the scintillation light emitting section 25 as shown in the figure, this device 22 also has high utilization efficiency of the light receiving surfaces 11a and 12a and radiation on the radiation incident surface 9a. This means that the radiation measurement device has a uniform detection sensitivity distribution.

[0008]

As described above, in the present invention, 1) any of the first scintillator and the first scintillator formed in a plate shape
A scintillation light emitting portion obtained by sequentially stacking an optical filter and a second scintillator, and a scintillation light emitting surface as a surface of the second scintillator that does not come into contact with the first optical filter of the scintillation light emitting portion. Through a first photoelectric converter that receives light through a second optical filter that is in contact with the second scintillator, a second optical filter, and a third optical filter that is in contact with the scintillation light emission surface of the second scintillator. A second photoelectric converter for receiving light, the third optical filter, and a non-simultaneous circuit to which output signals of both photoelectric converters are input,
Radiation measurement for measuring two types of radiation incident on the scintillation light emitting portion from the surface of the first scintillator that is not in contact with the first optical filter by the output signal of the non-simultaneous circuit and the output signal of the second photoelectric converter. A device, wherein both scintillators are made of the same material, the first and second optical filters are bandpass optical filters having the same light transmission characteristics, and the third optical filter is the first and second optical filters. The radiation measuring apparatus is configured to be a bandpass optical filter that transmits light in a wavelength band different from the light transmission wavelength band, and 2) the first scintillator and the first scintillator, both of which are plate-shaped.
A scintillation light emitting portion obtained by sequentially stacking an optical filter and a second scintillator, and a scintillation light emitting surface as a surface of the second scintillator that does not come into contact with the first optical filter of the scintillation light emitting portion. A first photoelectric converter that receives light through a second optical filter that is in contact with the second optical filter, the second optical filter, a second photoelectric converter that directly receives the scintillation light through a scintillation light emission surface, and both photoelectric converters. A non-simultaneous circuit to which each output signal of the converter is input, and from the surface of the first scintillator that is not in contact with the first optical filter by the output signal of the non-simultaneous circuit and the output signal of the first photoelectric converter A radiation measuring device for measuring two types of radiation incident on a scintillation light emitting part, wherein both optical filters have the same transmission characteristics. The radiation measuring apparatus is a band pass optical filter having, and the second scintillator is configured as a scintillator that emits the scintillation light in a wavelength band different from the light transmission wavelength band of the optical filters when the radiation enters. 3) In the radiation measuring apparatus described in 1) above, both scintillators are made of barium fluoride (BaF ₂ ), and the center wavelength of the light transmission wavelength band of the first and second optical filters and the third optical filter. The radiation measurement is performed by matching the center wavelength of the light transmission wavelength band of the above with each of two different peak wavelengths in the spectrum of the intensity of scintillation light generated in the barium fluoride when the radiation enters the barium fluoride. 4) The radiation measuring apparatus according to any one of 1) to 3) above. Then, the radiation measuring apparatus was constructed by using two kinds of radiation as β rays and γ rays.

Therefore, with the above arrangement, in any radiation measuring device, each light receiving surface of both photoelectric converters is connected to each of the second and third optical filters or to the second photoelectric converter. Since the light receiving surface of the scintillation light can be directly opposed to the scintillation light emitting surface of the scintillation light emitting section without passing through the third optical filter, the light receiving surface of the scintillation light emitting section can be connected to each light receiving surface of both photoelectric converters. The respective distances are almost uniform regardless of the radiation incident position on the radiation incident surface of the scintillation light emitting section, and therefore the utilization efficiency of each of the both light receiving surfaces is high and the radiation detection sensitivity distribution on the radiation incident surface is high. Thus, a radiation measuring device having a substantially uniform value can be obtained. Therefore, since the present invention does not take much time to measure both radiations, there is an effect that the accuracy of radiation measurement is improved when both radiations have a short half-life, and the radiation on the radiation incident surface of the scintillation light emitting unit is effective. Since the detection sensitivity distribution is uniform, the accuracy of radiation measurement is also improved for this reason.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a characteristic explanatory view of a main part in the embodiment shown in FIG.

FIG. 3 is a configuration diagram of an embodiment of the present invention different from the embodiment shown in FIG.

FIG. 4 is an explanatory view of characteristics of main parts in the embodiment shown in FIG.

FIG. 5 is a configuration diagram of a conventional radiation measuring apparatus.

FIG. 6 is a configuration diagram of a conventional radiation measuring apparatus different from the radiation measuring apparatus shown in FIG.

[Explanation of symbols]

 1 β Ray 2 γ Ray 9 First Scintillator 10 Second Scintillator 10a Scintillation Light Emitting Surface 11 First Photoelectric Converter 12 Second Photoelectric Converter 13 Non-simultaneous Circuit 14 First Optical Filter 15 Scintillation Light Emitting Section 16 Second Optical Filter 17 Third Optical Filter 20 Scintillation Light Intensity Spectrum 21 Radiation Measuring Device 22 Radiation Measuring Device 23 Second Scintillator 23a Scintillation Light Emitting Surface 24 Scintillation Light Intensity Spectrum 25 Scintillation Light Emitting Unit

Claims (4)

[Claims] 1. A scintillation light emitting section obtained by sequentially stacking a first scintillator, a first optical filter and a second scintillator, each of which has a plate shape, and scintillation light generated in the scintillation light emitting section. A first photoelectric converter that receives light via a second optical filter that is in contact with a scintillation light emission surface that is a surface of the second scintillator that does not contact the first optical filter, the second optical filter, and the scintillation. A second photoelectric converter that receives light through a third optical filter that is in contact with the scintillation light emission surface of the second scintillator, the third optical filter, and output signals of both photoelectric converters are input. And a first non-simultaneous circuit that is provided by the output signal of the non-simultaneous circuit and the output signal of the second photoelectric converter.
A radiation measuring device that measures two types of radiation incident on the scintillation light emitting portion from a surface of the scintillator that is not in contact with the first optical filter, wherein both scintillators are made of the same material, and 1st and 2nd
The optical filter is a bandpass optical filter having the same light transmission characteristics, and the third optical filter is a bandpass optical filter that transmits light in a wavelength band different from the light transmission wavelength bands of the first and second optical filters. And a radiation measuring device. 2. A scintillation light emitting section obtained by sequentially laminating a first scintillator, a first optical filter and a second scintillator, each of which has a plate shape, and scintillation light generated in the scintillation light emitting section. A first photoelectric converter that receives light via a second optical filter that is in contact with a scintillation light emission surface that is a surface of the second scintillator that does not contact the first optical filter, the second optical filter, and the scintillation. A second photoelectric converter for directly receiving light through the scintillation light emitting surface; and a non-simultaneous circuit to which the output signals of the both photoelectric converters are input. 1 The output signal of the photoelectric converter, the scintillation light emitting portion from the surface of the first scintillator which is not in contact with the first optical filter. A radiation measuring apparatus for measuring two types of incident radiation, wherein the both optical filters are bandpass optical filters having the same light transmission characteristic, and the second scintillator receives the radiation and the both optical filters. A radiation measuring apparatus, which is a scintillator that emits the scintillation light in a wavelength band different from the light transmission wavelength band. 3. The radiation measuring apparatus according to claim 1, wherein both scintillators are made of barium fluoride (BaF ₂ ), and the center wavelength of the light transmission wavelength band of the first and second optical filters and the third optical filter. The center wavelength of the light transmission wavelength band of the above is matched to each of two different peak wavelengths in the spectrum of the intensity of scintillation light generated in the barium fluoride when radiation is incident on the barium fluoride. Characteristic radiation measuring device. 4. The radiation measuring apparatus according to claim 1, wherein the two kinds of radiation are β rays and γ rays.