CN109143317B - Neutron detection method and equipment for reducing gamma ray interference by using CsI scintillator - Google Patents
Neutron detection method and equipment for reducing gamma ray interference by using CsI scintillator Download PDFInfo
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- CN109143317B CN109143317B CN201710455290.2A CN201710455290A CN109143317B CN 109143317 B CN109143317 B CN 109143317B CN 201710455290 A CN201710455290 A CN 201710455290A CN 109143317 B CN109143317 B CN 109143317B
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- G01—MEASURING; TESTING
- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
- G01T3/00—Measuring neutron radiation
- G01T3/06—Measuring neutron radiation with scintillation detectors
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- Y02E30/00—Energy generation of nuclear origin
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Abstract
The invention belongs to the technical field of radiation measurement, and particularly relates to a neutron detection method and equipment for reducing gamma-ray interference by using a CsI scintillator, which are used for 6 When the LiI scintillator detector detects neutron rays in the mixed radiation field, the LiI scintillator detector and the mixed radiation field are combined 6 A first voltage amplitude discrimination threshold is set in a first comparison circuit connected with the LiI scintillator, and the first voltage amplitude discrimination threshold is set 6 The method for detecting neutrons comprises the following steps of: (S1) at 6 A CsI scintillator detector adopting a CsI scintillator is arranged near the LiI scintillator; (S2) setting a second voltage amplitude discrimination threshold in a comparison circuit connected with the CsI scintillator; (S3) record employed 6 A first signal measured by the LiI scintillator; recording a second signal measured using a CsI scintillator; (S4) multiplying the second signal by a correction factor, and subtracting the second signal multiplied by the correction factor from the first signal to obtain a net neutron count rate.
Description
Technical Field
The invention belongs to the technical field of radiation measurement, and particularly relates to a neutron detection method and equipment for reducing gamma-ray interference by using a CsI scintillator.
Background
It is well known that the space particle radiation environment includes not only charged particles such as protons and electrons, but also uncharged particles such as neutrons (n) and X-rays. Neutrons have been a major uncharged particle, and neutron-related detection techniques have been a focus of research. Because a large amount of gamma rays are often accompanied in the presence of neutrons, the removal of interference of gamma rays on neutron signals is a research hotspot and difficulty in the field of neutron detection. The screening of neutrons and gamma rays is the basis of neutron detection technologies such as contraband detection, environmental radiation detection, military and deep space detection, and has extremely important theoretical and practical significance.
The neutron detector is selected with the exception of various performance metrics and parameters such as efficiency of neutron detection, energy or time-resolved performance, lifetime, etc. There is also a concern about whether it has good gamma-ray discrimination or poor gamma-ray response. 6 LiI scintillators are an important detector in neutron detection technology (is a high efficiency detector for detecting slow neutrons, especially thermal neutrons; e.g. 10mm thickness, enrichment) 6 The detection efficiency of the Li lithium iodide scintillator for thermal neutrons reaches 100 percent, the material density is high, the stopping power is strong, the detection sensitivity is high, and the material is sensitive to gamma rays (see figure 2). The experiment shows that the preparation method has the advantages of, 6 the LiI scintillator has better gamma radiation resistance under the irradiation of low-energy gamma rays. But for high energy gamma rays with energies greater than 1MeV, the detection sensitivity is high, which is extremely detrimental to its mid-detection. Thus using 6 How to reduce or eliminate the gamma-ray response of LiI scintillators when detecting neutron rays is one of the key issues that they have to solve. At present, using 6 When the LiI scintillator is used as a detector of the neutron dose equivalent rate instrument, the gamma ray signals are removed mainly by adopting a pulse amplitude discrimination technology, namely, neutron rays and gamma rays are utilized in the process of 6 The difference of signal pulse amplitude is generated in LiI scintillator 6 And a voltage amplitude discrimination threshold is set in a comparison circuit connected with the LiI scintillator, and gamma pulses with lower amplitude are blocked, so that only neutron signals are recorded. This method works well with lower gamma energy, but ignores the high energy gamma rays at 6.0MeV 6 The energy deposited in the LiI scintillator can be summed 6 Li (α, n) reacts as much. The actual n-gamma ratio drops from 1000:1 at 1.0MeV to 1:1 at 6.0 MeV. The response caused by gamma rays will seriously interfere with the measurement result of neutron dose, so the common pulse amplitude discrimination technology has high-energy gamma in the mixed radiation fieldIn the case of radiation, large deviations occur.
Disclosure of Invention
For effective use 6 The LiI scintillator detects neutron rays, and gamma ray interference is extremely necessary to be reduced through a gamma ray signal discrimination technology. Considering that the CsI scintillator has the advantage of being sensitive to gamma-particle radiation and relatively insensitive to neutron radiation, this characteristic is very significant in improving the shielding of gamma-radiation interference when measuring neutron rays in a mixed radiation field of n, gamma-mixing, so 6 The two scintillators, liI and CsI, combine to detect neutron radiation. In detecting a mixed radiation field, from 6 And in the output signals of the LiI scintillators, the output signals of the CsI scintillators are buckled according to corresponding proportion, so that the net neutron signals in the mixed radiation field can be obtained.
In order to achieve the aim, the invention adopts the technical scheme that the neutron detection method for reducing gamma-ray interference by using the CsI scintillator is realized by adopting 6 LiI scintillator 6 When the LiI scintillator detector detects neutron rays in the mixed radiation field, the LiI scintillator detector and the neutron rays in the mixed radiation field are detected 6 Setting a first voltage amplitude discrimination threshold in a first comparison circuit connected with the LiI scintillator, and carrying out the steps 6 The method for detecting neutrons by using the CsI scintillator to reduce gamma ray interference comprises the following steps of:
(S1) in the process 6 A CsI scintillator detector adopting a CsI scintillator is arranged near the LiI scintillator;
(S2) setting a second voltage amplitude discrimination threshold in a comparison circuit connected with the CsI scintillator, and filtering out the low-energy gamma ray signals detected by the CsI scintillator;
(S3) recording the first signal and the second signal; the first signal includes the 6 Counting rates of the neutron rays and the high-energy gamma rays measured by the LiI scintillator; the second signal is the counting rate of the high-energy gamma rays measured by the CsI scintillator;
(S4) calculating a net neutron count rate, multiplying the second signal by a correction coefficient, and obtaining the net neutron count rate by subtracting the second signal multiplied by the correction coefficient from the first signal.
Further, the method comprises the steps of,
the first voltage amplitude discrimination threshold is that the energy of the gamma rays is 662keV 6 The voltage amplitude value obtained by detection of the LiI scintillator;
the second voltage amplitude discrimination threshold is the voltage amplitude detected by the CsI scintillator when the energy of the gamma rays is 662 keV;
the low-energy gamma rays refer to gamma rays with energy less than or equal to 662 keV; the high-energy gamma rays refer to gamma rays with energy greater than 662 keV.
Further, in said step (S1), also included in said 6 A neutron response layer is arranged outside the LiI scintillator; the CsI scintillator is arranged in the middle of the neutron response layer; the neutron response layer is a polyethylene moderating body; the thickness of the polyethylene moderated body is 8-10cm.
Further, the method comprises the steps of,
the obtaining of the correction coefficient in the step (S4) includes the steps of:
(S4.1) a gamma radiation source having an energy of 662keV-3MeV is disposed at a distance from the 6 The LiI scintillator and the CsI scintillator are arranged at an irradiation position with a linear distance of 60 cm;
(S4.2) irradiating the gamma rays of different energy segments between 662keV and 3MeV with the gamma radiation source 6 LiI scintillator, csI scintillator, and recording the same 6 The counting rates of the LiI scintillator and the CsI scintillator measured under the gamma ray irradiation of different energy sections;
(S4.3) calculating the gamma-ray irradiation of the same energy segment 6 Ratios of count rates measured for LiI scintillator, csI scintillator;
(S4.4) averaging the ratio measured under gamma irradiation of each of the energy segments in step (S4.3), the average being the correction factor.
Further, the calculation formula of the net neutron counting rate is as follows:
H (n) ＝H (n,γ) -H (γ) *K
wherein:
H (n) -the net neutron count rate resulting;
H (n,γ) -from said 6 Neutron rays measured by LiI scintillators and methods of use thereof 6 A count rate of the high energy gamma rays having an energy measured by the LiI scintillator higher than 662 keV;
H (γ) -a count rate of the high energy gamma rays measured by the CsI scintillator being higher than 662 keV;
k—correction factor for subtracting the count rate of high energy gamma rays measured by the CsI scintillator above 662 keV.
To achieve the above object, the present invention also discloses a neutron detection device for reducing gamma-ray interference using a CsI scintillator for the neutron detection method described above, comprising 6 LiI scintillator detector, the 6 The LiI scintillator detector comprises the following components which are connected in sequence 6 The LiI scintillator, a first PIN light emitting diode provided with bias voltage, a first pre-amplifying circuit, a first comparing circuit, a first shaping circuit and a singlechip system, wherein a first voltage amplitude discrimination threshold value is set in the first comparing circuit to carry out the following steps 6 Filtering out signals of low-energy gamma rays detected by the LiI scintillator; the system also comprises a CsI scintillator detector which is connected with the singlechip system and adopts a CsI scintillator, wherein a second voltage amplitude discrimination threshold is set in a comparison circuit which is connected with the CsI scintillator, and signals of low-energy gamma rays which are measured by the CsI scintillator are filtered.
Further, the method comprises the steps of,
the CsI scintillator detector comprises a CsI scintillator, a second PIN light-emitting diode provided with bias voltage, a second pre-amplifying circuit, a second comparing circuit and a second shaping circuit which are sequentially connected, and the second shaping circuit is connected with the singlechip system;
the second voltage amplitude discrimination threshold is set in the second comparison circuit.
Still further still, the method further comprises,
the first voltage amplitude discrimination threshold is that the energy of the gamma rays is 662keV 6 The voltage amplitude value obtained by detection of the LiI scintillator;
the second voltage amplitude discrimination threshold is the voltage amplitude detected by the CsI scintillator when the energy of the gamma rays is 662 keV;
the low-energy gamma rays refer to gamma rays with energy less than or equal to 662 keV; the high-energy gamma rays refer to gamma rays with energy greater than 662 keV.
Further, in the described 6 A neutron response layer is arranged outside the LiI scintillator, and the CsI scintillator is arranged close to the LiI scintillator 6 The position of the LiI scintillator; the neutron response layer is used for slowing down the neutron rays to be detected into thermal neutrons, so that the neutron rays are convenient to use 6 And measuring the neutron rays by the LiI scintillator.
Still further, the CsI scintillator is disposed at the 6 The neutron response layer outside the LiI scintillator is in the middle.
Further, the neutron response layer is a polyethylene moderated body, and the thickness of the polyethylene moderated body is 8-10cm.
The invention has the beneficial effects that:
the monitoring of the mixed radiation field of neutrons with gamma rays is facilitated, and more favorable conditions are provided for radiation protection work, wherein:
1. by and at 6 A first voltage amplitude discrimination threshold is set in a first comparison circuit connected with the LiI scintillator, so that interference of low-energy gamma rays on neutron measurement is solved; by at least one of 6 A CsI scintillator detector adopting a CsI scintillator is arranged near the LiI scintillator, and a second voltage amplitude discrimination threshold is arranged in a comparison circuit connected with the CsI scintillator, so that interference of high-energy gamma rays on neutron measurement is solved;
2. by definitely defining the first voltage amplitude discrimination threshold and the second voltage amplitude discrimination threshold, the method ensures 6 The LiI scintillator and the CsI scintillator filter the low energy gamma ray signal,further ensuring the accuracy of the final net neutron counting rate; accurately distinguish low-energy gamma rays and high-energy gamma rays by taking 662keV energy as boundary, ensure 6 The LiI scintillator filters the low-energy gamma ray signals, so that the accuracy of the CsI scintillator in measuring the high-energy gamma rays is also ensured;
3. by at least one of 6 The neutron response layer arranged outside the LiI scintillator can increase the response of neutrons (neutron rays) and improve 6 The detection effect of the LiI scintillator on neutrons (neutron rays); the CsI scintillator is arranged in the middle of the neutron response layer, so that the detection effect of the CsI scintillator on the high-energy gamma rays can be ensured to be more accurate;
4. the material and thickness of the mesoresponsive layer are optimized (the material is polyethylene moderated body, the thickness is 8-10 cm) 6 The LiI scintillator has more accurate detection effect on neutrons (neutron rays);
5. the accuracy of calculating the net neutron count rate can be further improved by optimizing the numerical range of the correction coefficient.
Drawings
FIG. 1 is a schematic diagram of a peripheral circuit configuration of a neutron detection device using a CsI scintillator to reduce gamma-ray interference according to an embodiment of the present invention;
FIG. 2 is a schematic illustration of the prior art 6 A response curve graph of the LiI scintillator to thermal neutrons (neutron rays after moderation by the neutron response layer) and gamma rays;
FIG. 3 is a graph of the energy response of a CsI scintillator to gamma rays in accordance with an embodiment of the present invention, wherein the abscissa indicates the energy of gamma rays and the ordinate indicates the response of the CsI scintillator to gamma rays;
in the figure: 1- 6 The LED lamp comprises a LiI scintillator, a 2-first PIN light emitting diode, a 3-bias voltage, a 4-first pre-amplifying circuit, a 5-first comparing circuit, a 6-first shaping circuit, a 7-single chip microcomputer system, an 8-CsI scintillator, a 9-second PIN light emitting diode, a 10-second pre-amplifying circuit, an 11-second comparing circuit and a 12-second shaping circuit.
Detailed Description
The invention is further described below with reference to the drawings and examples.
The CsI scintillator has the characteristics of high density, high atomic coefficient, high gamma and X-ray detection efficiency, high gamma ray sensitivity and strong charged particle blocking capability, is insensitive to the response of the neutron rays, and is suitable for the detection of the gamma rays 6 The response of the LiI scintillator to the sub-rays is negligible compared. The energy response of the CsI scintillator is not linear, and in order to obtain a better energy response, the CsI scintillator needs to be subjected to corresponding energy compensation, and the energy response of the CsI scintillator after energy compensation is good (see fig. 3, the energy response curve of the CsI scintillator to gamma rays). Thus in 6 A CsI scintillator detector is arranged near the LiI scintillator, for 6 The count rate measured by the LiI scintillator is subtracted from the count rate measured by the CsI scintillator in a corresponding proportion, so that a more accurate net neutron count rate can be obtained.
The neutron detection method for reducing gamma-ray interference by using the CsI scintillator provided by the invention adopts 6 LiI scintillator 6 When the LiI scintillator detector detects neutron rays in the mixed radiation field, the LiI scintillator detector is used for solving the influence of low-energy gamma rays on the measurement effect 6 A first voltage amplitude discrimination threshold is set in a first comparison circuit connected with the LiI scintillator, and the first voltage amplitude discrimination threshold is set 6 Filtering out signals of low-energy gamma rays detected by the LiI scintillator; thereby recording only the signal of the detected neutron ray; in order to solve the influence of high-energy gamma rays on the measurement effect, the method comprises the following steps:
step S1, in 6 A CsI scintillator detector adopting a CsI scintillator is arranged near the LiI scintillator;
step S2, setting a second voltage amplitude discrimination threshold in a comparison circuit connected with the CsI scintillator, and filtering out signals of low-energy gamma rays detected by the CsI scintillator;
step S3, recording adoption 6 A first signal measured by the LiI scintillator, the first signal including 6 Counting rates of neutron rays and high-energy gamma rays measured by the LiI scintillator; recording a second signal measured by the CsI scintillator, wherein the second signal is the high-energy gamma ray measured by the CsI scintillatorCounting rate;
and S4, calculating a net neutron count rate, multiplying the second signal by a correction coefficient, and subtracting the second signal multiplied by the correction coefficient from the first signal to obtain the net neutron count rate.
Wherein, in step S4, obtaining the correction coefficient includes the steps of:
step S4.1, the gamma radiation source with the energy of 662keV-3MeV is arranged at a distance 6 The LiI scintillator and the CsI scintillator are arranged at an irradiation position with a linear distance of 60 cm;
step S4.2, generating gamma-ray irradiation of different energy segments between 662keV-3MeV by gamma-ray source 6 LiI scintillator, csI scintillator, and recording 6 The counting rates of the LiI scintillator and the CsI scintillator are measured under the gamma ray irradiation of different energy sections;
step S4.3, calculating the gamma-ray irradiation under the same energy section 6 Ratios of count rates measured for LiI scintillator, csI scintillator;
and step S4.4, averaging the ratio measured under the gamma-ray irradiation of each energy segment in the step S4.3, wherein the average value is the correction coefficient.
The specific values of the correction factors will vary depending on the type, size, etc. of CsI scintillator selected.
In order to enhance the response of neutrons (neutron rays), the method is also included in step (S1) 6 LiI scintillator detector 6 A neutron response layer is arranged outside the LiI scintillator; disposing a CsI scintillator in a middle portion of the neutron response layer; the neutron response layer is a polyethylene moderating body; the thickness of the polyethylene moderated body is 8-10cm.
Wherein when the first voltage amplitude discrimination threshold is 662keV of gamma rays energy 6 The voltage amplitude value obtained by detection of the LiI scintillator;
the voltage amplitude detected by the CsI scintillator is detected when the second voltage amplitude discrimination threshold is 662keV of gamma rays;
the low-energy gamma rays refer to gamma rays with energy less than or equal to 662 keV; high energy gamma rays refer to gamma rays having energies greater than 662 keV. In the present invention, the high energy gamma rays are specifically gamma rays between 662keV and 3 MeV.
The calculation formula of the net neutron count rate is as follows:
H (n) ＝H (n,γ) -H (γ) *K
wherein:
H (n) -the net neutron count rate resulting;
H (n,γ) -by 6 The counting rate of neutron rays and high-energy gamma rays with energy higher than 662keV measured by the LiI scintillator;
H (γ) -the count rate of high energy gamma rays with energies measured by the CsI scintillator higher than 662 keV;
k—correction factor for subtracting the count rate of high energy gamma rays measured by CsI scintillator at energies above 662 keV.
Thus, the method provided by the invention can give the net neutron count rate of the mixed radiation field for the mixed radiation field with unknown energy and unknown fluence, no matter whether the gamma rays belong to high energy or low energy.
The above-mentioned conditions for discriminating the two scintillator detectors when the gamma ray is 662keV are considered because:
1. at a gamma-ray energy of 662keV, 6 the LiI scintillator can measure a significantly smaller amplitude than the thermal neutrons (neutron rays after being moderated by the neutron response layer);
2. gamma-ray energies are on the order of 662keV to 3MeV, and CsI scintillators tend to respond steadily over this energy range;
the Cs-137 radioactive source emits gamma rays with energy of 662keV, which is easily obtained as an experimental condition.
The invention also discloses neutron detection equipment for reducing gamma-ray interference by using the CsI scintillator, and the neutron detection equipment is used for measuring the net neutron counting rate in the mixed radiation field by using the neutron detection method. The neutron detection device comprises 6 LiI scintillator detectors and CsI scintillator detectors (see fig. 1).
Wherein, the liquid crystal display device comprises a liquid crystal display device, 6 the LiI scintillator detector comprises sequentially connected 6 The LiI scintillator 1, a first PIN light-emitting diode 2 (provided with a bias voltage 3), a first pre-amplifying circuit 4, a first comparing circuit 5, a first shaping circuit 6 and a singlechip system 7, wherein a first voltage amplitude discrimination threshold value is set in the first comparing circuit 5 to be compared with 6 The signals of the low-energy gamma rays detected by the LiI scintillator 1 are filtered;
the CsI scintillator detector is also connected with the singlechip system 7 and is used for recording signals of high-energy gamma rays. The CsI scintillator detector comprises a CsI scintillator 8, a second PIN light-emitting diode 9 (provided with a bias voltage 3), a second pre-amplifying circuit 10, a second comparing circuit 11 and a second shaping circuit 12 which are connected in sequence; wherein the second shaping circuit 12 is connected with the singlechip system 7. A second voltage amplitude discrimination threshold is set in the second comparison circuit 11, and the low-energy gamma ray signal detected by the CsI scintillator 8 is filtered out.
When the first voltage amplitude discrimination threshold is 662keV of gamma rays 6 The voltage amplitude detected by the LiI scintillator 1;
the voltage amplitude detected by the CsI scintillator 8 when the second voltage amplitude discrimination threshold is 662keV of gamma-ray energy;
the low-energy gamma rays refer to gamma rays with energy less than or equal to 662 keV; high energy gamma rays refer to gamma rays having energies greater than 662 keV. In the present invention, the high energy gamma rays are specifically gamma rays between 662keV and 3 MeV.
At the position of 6 The neutron response layer is arranged outside the LiI scintillator 1 (to increase neutron response), and the CsI scintillator 8 is arranged close to 6 The location of the LiI scintillator 1, specifically the CsI scintillator 8 can be arranged in 6 The neutron response layer outside the LiI scintillator 1 is in the middle. (the specific position of the CsI scintillator 8 can then be determined by 6 The direction and position of the LiI scintillator 1 are adjusted as much as possible 6 The LiI scintillator 1 is positioned close). The neutron response layer is a polyethylene moderated body. The thickness of the polyethylene moderated body is 8-10cm. The neutron response layer is used for slowing down the neutron rays to be measured into thermal neutrons, and is convenient for 6 Measurement of neutron rays by LiI scintillators.
As shown in FIG. 1, the CsI scintillator 8 6 LiI scintillator 1 minThe PIN light emitting diodes are connected respectively, signals output by the two PIN light emitting diodes enter respective pre-amplifying circuits to amplify the signals, and the amplified signals enter respective comparison circuits to perform threshold value discrimination to obtain a first signal # 6 The count rate of neutrons and high-energy gamma rays detected by the LiI scintillator 1) and a second signal (the count rate of high-energy gamma rays detected by the CsI scintillator 8). Here the number of the elements is the number, 6 when the threshold value of the discrimination signal (first voltage amplitude discrimination threshold value) of the LiI scintillator 1 is 662keV 6 The magnitude of the voltage detected by the LiI scintillator 1, and the threshold value of the discrimination signal of the CsI scintillator 8 (second voltage magnitude discrimination threshold value) is set to be equal to the magnitude of the voltage detected by the CsI scintillator 8 when the gamma ray is 662 keV. This ensures that when the gamma energy is low, 6 the amplitude discrimination technique of the LiI scintillator 1 itself (using the first voltage amplitude discrimination threshold) rejects the portion of low energy gamma rays, whereas when the gamma ray energy is high, the CsI scintillator 8 makes a measurement of the gamma ray energy in the range from 662keV to 3MeV, 6 the first signal measured by the LiI scintillator 1 strips the second signal measured by the CsI scintillator 8. The first signal and the second signal after passing through the respective comparison circuits enter the singlechip system 7 for data processing after passing through the respective shaping circuits, and the net neutron counting rate is obtained.
The calculation formula of the net neutron count rate is as follows:
H (n) ＝H (n,γ) -H (γ) *K
wherein:
H (n) -the net neutron count rate resulting;
H (n,γ) -by 6 The counting rate of neutron rays and high-energy gamma rays with energy higher than 662keV measured by the LiI scintillator 1;
H (γ) -the count rate of high energy gamma rays with energies measured by the CsI scintillator 8 higher than 662 keV;
k—correction coefficient for subtracting the count rate of high energy gamma rays measured by CsI scintillator 8 with energy above 662 keV.
The device according to the invention is not limited to the examples described in the specific embodiments, and a person skilled in the art obtains other embodiments according to the technical solution of the invention, which also belong to the technical innovation scope of the invention.
Claims (10)
1. Neutron detection method for reducing gamma-ray interference by using CsI scintillator 6 LiI scintillator 6 When the LiI scintillator detector detects neutron rays in the mixed radiation field, the LiI scintillator detector and the neutron rays in the mixed radiation field are detected 6 Setting a first voltage amplitude discrimination threshold in a first comparison circuit connected with the LiI scintillator, and carrying out the steps 6 The method is characterized in that in order to solve the influence of high-energy gamma rays on the measurement effect, the neutron detection method for reducing gamma ray interference by using the CsI scintillator is adopted, and comprises the following steps:
(S1) in the process 6 A CsI scintillator detector adopting a CsI scintillator is arranged near the LiI scintillator;
(S2) setting a second voltage amplitude discrimination threshold in a comparison circuit connected with the CsI scintillator, and filtering out the low-energy gamma ray signals detected by the CsI scintillator;
(S3) recording the first signal and the second signal; the first signal includes the 6 Counting rates of the neutron rays and the high-energy gamma rays measured by the LiI scintillator; the second signal is the counting rate of the high-energy gamma rays measured by the CsI scintillator;
(S4) calculating a net neutron count rate, multiplying the second signal by a correction coefficient, and obtaining the net neutron count rate by subtracting the second signal multiplied by the correction coefficient from the first signal.
2. The neutron detection method of claim 1, wherein:
the first voltage amplitude discrimination threshold is that the energy of the gamma rays is 662keV 6 The voltage amplitude value obtained by detection of the LiI scintillator;
the second voltage amplitude discrimination threshold is the voltage amplitude detected by the CsI scintillator when the energy of the gamma rays is 662 keV;
the low-energy gamma rays refer to gamma rays with energy less than or equal to 662 keV; the high-energy gamma rays refer to gamma rays with energy greater than 662 keV.
3. The neutron detection method of claim 1, wherein: also included in the step (S1) 6 A neutron response layer is arranged outside the LiI scintillator; the CsI scintillator is arranged in the middle of the neutron response layer; the neutron response layer is a polyethylene moderating body; the thickness of the polyethylene moderated body is 8-10cm.
4. The neutron detection method of claim 1, wherein: the obtaining of the correction coefficient in the step (S4) includes the steps of:
(S4.1) a gamma radiation source having an energy of 662keV-3MeV is disposed at a distance from the 6 The LiI scintillator and the CsI scintillator are arranged at an irradiation position with a linear distance of 60 cm;
(S4.2) irradiating the gamma rays of different energy segments between 662keV and 3MeV with the gamma radiation source 6 LiI scintillator, csI scintillator, and recording the same 6 The counting rates of the LiI scintillator and the CsI scintillator measured under the gamma ray irradiation of different energy sections;
(S4.3) calculating the gamma-ray irradiation of the same energy segment 6 Ratios of count rates measured for LiI scintillator, csI scintillator;
(S4.4) averaging the ratio measured under gamma irradiation of each of the energy segments in step (S4.3), the average being the correction factor.
5. A neutron detection device for reducing gamma-ray interference using a CsI scintillator for implementing the neutron detection method of any one of claims 1 to 4, comprising 6 LiI scintillator detector, the 6 The LiI scintillator detector comprises the following components which are connected in sequence 6 LiI scintillator (1), first with bias voltage (3)PIN light emitting diode (2), first pre-amplifier circuit (4), first comparison circuit (5), first shaping circuit (6), singlechip system (7), wherein set up first voltage amplitude and discriminate threshold in first comparison circuit (5), will the said 6 Filtering out signals of low-energy gamma rays detected by the LiI scintillator; the method is characterized in that: the system also comprises a CsI scintillator detector which is connected with the singlechip system (7) and adopts a CsI scintillator (8), wherein a second voltage amplitude discrimination threshold is set in a comparison circuit which is connected with the CsI scintillator (8), and signals of low-energy gamma rays detected by the CsI scintillator (8) are filtered.
6. The neutron detection device of claim 5, wherein:
the CsI scintillator detector comprises a CsI scintillator (8), a second PIN light-emitting diode (9) provided with a bias voltage (3), a second pre-amplifying circuit (10), a second comparing circuit (11) and a second shaping circuit (12) which are sequentially connected, and the second shaping circuit (12) is connected with the singlechip system (7);
the second voltage amplitude discrimination threshold is set in the second comparison circuit (11).
7. The neutron detection device of claim 5, wherein:
the first voltage amplitude discrimination threshold is that the energy of the gamma rays is 662keV 6 The voltage amplitude obtained by detection of the LiI scintillator (1);
the second voltage amplitude discrimination threshold is the voltage amplitude detected by the CsI scintillator (8) when the energy of the gamma rays is 662 keV;
the low-energy gamma rays refer to gamma rays with energy less than or equal to 662 keV; the high-energy gamma rays refer to gamma rays with energy greater than 662 keV.
8. The neutron detection device of claim 5, wherein: at the said 6 A neutron response layer is arranged outside the LiI scintillator (1), and the CsI scintillator (8) is arranged close to the neutron response layer 6 The position of the LiI scintillator (1); the middle partThe sub-response layer is used for slowing down the neutron rays to be measured into thermal neutrons, so that the neutron rays are convenient to use 6 And measuring the neutron rays by the LiI scintillator.
9. The neutron detection device of claim 8, wherein: the CsI scintillator (8) is arranged at the 6 -a middle portion of the neutron response layer outside the LiI scintillator (1).
10. The neutron detection device of claim 8, wherein: the neutron response layer is a polyethylene moderated body, and the thickness of the polyethylene moderated body is 8-10cm.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201710455290.2A CN109143317B (en) | 2017-06-16 | 2017-06-16 | Neutron detection method and equipment for reducing gamma ray interference by using CsI scintillator |
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| CN201710455290.2A CN109143317B (en) | 2017-06-16 | 2017-06-16 | Neutron detection method and equipment for reducing gamma ray interference by using CsI scintillator |
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| CN109143317A CN109143317A (en) | 2019-01-04 |
| CN109143317B true CN109143317B (en) | 2023-05-16 |
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