CN214668716U - Can dismantle parcel explosive neutron detection device - Google Patents
Can dismantle parcel explosive neutron detection device Download PDFInfo
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- CN214668716U CN214668716U CN202022988103.7U CN202022988103U CN214668716U CN 214668716 U CN214668716 U CN 214668716U CN 202022988103 U CN202022988103 U CN 202022988103U CN 214668716 U CN214668716 U CN 214668716U
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Abstract
The utility model discloses a neutron detection device, this detection device include neutron generator, alpha particle position sensitive detector, neutron source radiation shield, neutron receiving cavity, gamma ray detector, system control and data acquisition and processing system. The neutron detection device for the detachable covered explosives of the utility model greatly improves the efficiency of the detector by placing the gamma detector beside the neutron beam outlet hole channel between the neutron source radiation shield and the neutron receiving cavity and close to the detected object; the detachable shielding body adopted by the device is convenient for the detection device to move and use in a manned place, so that nondestructive qualitative detection of suspicious luggage and packages in random places is conveniently realized, the detection efficiency is high, and in addition, the device can also detect hidden drugs.
Description
Technical Field
The utility model belongs to hide explosive detection area, concretely relates to can dismantle parcel explosive neutron detection device.
Background
Concealed explosives detection is one of the issues of general international concern, and accurate, sensitive, non-destructive detection of explosives is one of the most important concerns in the security industry. At present, the detection is mainly carried out by adopting X-rays, and the approximate outline of the detected object can be obtained, but the detection cannot be distinguished from the element level. The neutron detection method can detect from an element level and is a beneficial supplement to the X-ray detection method. Through development of half a century, common neutron detection methods include a thermal neutron method, a fast neutron method, a pulse fast thermal neutron method and the like, in the detection of explosives by using thermal neutrons, the thermal neutrons and nitrogen in explosives are mainly used for capture reaction to generate high-energy gamma of 10.8MeV, but due to the interference of surrounding nitrogen-containing non-explosives and the discrimination by using only one element, the false alarm rate is high, and particularly, a large amount of N exists in the air, so that great interference can be generated; the fast neutron method can avoid using an element to discriminate the explosive, but the fast neutron can also generate the same characteristic gamma ray under the action of non-explosive substances around the explosive; in order to utilize fast neutrons and thermal neutrons simultaneously, a pulse fast thermal neutron method is developed for explosive detection, but the detection cannot be positioned from space and is interfered by surrounding environment objects. Therefore, the key technology for detecting hidden explosives by neutrons is to screen the environmental objects around the detected object and eliminate the environmental interference; secondly, daily supplies with similar density and same elements as explosives, narcotics and the like can be screened; and thirdly, detection is carried out under the condition that a box is not opened (namely, a coating is arranged outside the box or the box is intentionally placed on some shielding objects), and shielding is also needed due to radiation damage of neutrons to the environment. Techniques for concealed explosives detection have thus been developed along with alpha particle imaging/neutron time of flight (API/TOF). The neutron detection method can meet the following conditions: the space positioning detection can be realized, and the anti-interference performance is strong; the method can realize the measurement of related elements of the explosives, and can greatly reduce the false alarm rate compared with other methods which only measure one element.
The Chinese patent with the application number of 201621106604.5 discloses a neutron detection device for a detachable packaged explosive, which comprises a neutron generator, an alpha particle position sensitive detector, a shielding body, a gamma ray detector, a control system and a data acquisition and processing system; the neutron generator and the gamma-ray detector are positioned on the same side of the detected object, and the shielding body is arranged between the neutron generator and the gamma-ray detector. The explosive detection system has high spatial resolution, and realizes effective detection of the parcel explosives. However, the tungsten shield 5 of the device can only shield the detector and can not carry out biological shielding; the detector 2 is far away from the package, the efficiency is low, and the use cost of the device can be increased only by increasing the measurement time or improving the neutron yield.
Disclosure of Invention
For solving the current problem that the parcel explosive detection system who adopts along with alpha particle/neutron time of flight method (API/TOF) exists, be convenient for detect suspicious parcel explosive in random place, the utility model provides a can dismantle parcel explosive neutron detection device. The device solves the problems of radiation protection of the detection system for the parcel explosives and improves the efficiency of the detector.
The utility model discloses specifically adopt following technical scheme:
a neutron detection device for a detachable packaged explosive comprises a neutron generator, an alpha particle position sensitive detector, a detachable neutron source radiation shield, a neutron receiving cavity, a gamma ray detector and a system control and data acquisition and processing system; the detachable neutron source radiation shield is formed by tightly combining an outer layer, an intermediate layer and an inner layer from outside to inside; the gamma-ray detector is positioned between the neutron generator and the detected object and outside the neutron emitting pore channel so as to improve the detection efficiency; the neutron receiving cavity is positioned behind the neutron emergent pore channel; the neutron generator is placed in the inner layer of the detachable neutron source radiation shielding body, and the bottom surface of the neutron emitting pore channel is horizontal; the object to be detected is placed on the supporting platform, the upper surface of the supporting platform is parallel to the bottom surface of the neutron emitting pore channel and lower than the bottom surface of the neutron emitting pore channel, and the gamma-ray detector is placed below the supporting platform.
The neutron generator is a deuterium-tritium neutron generator.
The alpha particle position sensitive detector adopts a detection material selected from ZnO scintillators, PIN semiconductors or YAP: ce scintillator.
The scintillator of the gamma-ray detector is LaBr3Any one of a scintillator, a BGO scintillator, or a NaI scintillator.
The detachable neutron source radiation shield is characterized in that the outer layer is a polyethylene layer, the middle layer is a boron-containing polyethylene layer, and the inner layer is a tungsten layer or an iron layer.
The neutron receiving cavity is composed of concave iron, a polyethylene plate and a boron-containing polyethylene plate.
Drawings
FIG. 1 is a top view of the device of the present invention;
FIG. 2 is a side view of the device of the present invention;
in the figure, the device comprises an outer layer 1, an intermediate layer 3, an inner layer 4, a neutron generator 5, neutron emitting pore channels 6, a gamma-ray detector 7, a detected object 8, a supporting platform 9, concave iron 10, a polyethylene plate 11, a boron-containing polyethylene plate 12, a system control and data acquisition processing system.
Detailed Description
The present invention will be explained in further detail with reference to the drawings and examples.
A neutron detection device for a detachable packaged explosive comprises a neutron generator 4, an alpha particle position sensitive detector, a detachable neutron source radiation shield, a neutron receiving cavity, a gamma ray detector 6 and a system control and data acquisition and processing system 12; the detachable neutron source radiation shield is formed by tightly combining an outer layer 1, an intermediate layer 2 and an inner layer 3 from outside to inside; the gamma-ray detector is positioned between the neutron generator and the detected object and outside the neutron emitting pore channel so as to improve the detection efficiency; the neutron receiving cavity is positioned behind the neutron emergent pore channel; the neutron generator is placed in an inner cavity of a detachable neutron source radiation shielding body, a neutron emitting pore passage 5 is a quadrangular pyramid hole, and the bottom surface is horizontal; the detected object is placed on a supporting platform 8, the upper surface of the supporting platform 8 is parallel to the bottom surface of the neutron emitting pore channel and is about 1cm lower than the bottom surface of the neutron emitting pore channel, and a gamma-ray detector 6 is placed 2cm below the supporting platform 8; the neutron receiving cavity is composed of concave iron 9, polyethylene sheet l0 and boron-containing polyethylene sheet 11. The distance between the bottom of the concave iron and the detected object 7 is 15 cm-20 cm. The system control and data acquisition processing system 12 controls the system, acquires and analyzes data, and gives results.
Further, the neutron generator is a deuterium-tritium neutron generator.
Further, the detection material adopted by the alpha particle position sensitive detector is selected from ZnO scintillator, PIN semiconductor or YAP: ce scintillator.
Furthermore, the scintillator of the gamma-ray detector adopts LaBr3Any one of a scintillator, a BGO scintillator, or a NaI scintillator.
Furthermore, the detachable neutron source radiation shield has an outer layer 1 of a polyethylene layer, an intermediate layer 2 of a boron-containing polyethylene layer and an inner layer 3 of a tungsten layer or an iron layer. The inner layer structure of the shielding body is prepared by selecting tungsten with higher density and better moderation, so that the volume of the whole shielding body can be reduced.
Further, the neutron receiving cavity is composed of concave iron 9, a polyethylene plate 10 and a boron-containing polyethylene plate 11.
The utility model discloses a can dismantle parcel explosive neutron detection device's detection principle as follows:
in the nuclear reaction of T (d, n) α, α is temporally correlated with a neutron. The neutrons associated with the alpha react with the substance to generate prompt gamma, the time for the neutrons to react with the substance to generate the prompt gamma is extremely short, therefore, the gamma and the alpha are also associated in time, the gamma generated by other neutrons are not associated with the alpha in time to form a background, a relevant time spectrum of the gamma is obtained through coincidence measurement of gamma and alpha signals, the prompt gamma associated with alpha particles can be selected through a time window, a characteristic gamma spectral line of a sample is obtained, meanwhile, the irrelevant gamma background is greatly reduced, and the analysis of the gamma spectrum is facilitated. D-T neutrons and the main element C, N, O of the explosive generate non-elastic scattering to generate a characteristic prompt gamma main reaction channel:
n+16O-16O*+n′(E*＝6.13MeV)
n+12C-12C*+n′(E*＝4.43MeV)
n+14N-14N*+n′(E*＝5.11MeV、2.31MeV)
the characteristic prompt gamma energy is more than 2MeV, and the material can penetrate through a thicker material, so that the hidden explosive can be detected conveniently.
First step, neutron marking: d (deuterium) + T (tritium) → n (neutron) + alpha, the energy of the produced neutrons is about 14.1MeV, and the speed is 5.2 cm/ns; the energy of the alpha particles was about 3.5MeV and the velocity of the alpha particles was 1.3 cm/ns. The alpha particles and neutrons are emitted in a back direction, the running direction is approximately on the same straight line, the array ZnO scintillator records the alpha particles, the array units detected by the alpha particles and the detected time are recorded, the neutron direction is marked, and the takeoff time of the neutrons is determined. Therefore, the time of neutron generation can be deduced by detecting the time of alpha particles, and the emission direction of neutrons can be determined by detecting the array units of the alpha particles, namely, the alpha particles measured by certain array units are marked with the neutron generation time and the emission direction related to the alpha particles.
And the second step of gamma ray detection: when neutrons with the energy of 14.1MeV and the detected substance generate inelastic scattering, characteristic gamma is emitted, and the gamma is characteristic rays (or fingerprints) of elements, so that information of the constituent elements of the detected object substance can be obtained.
Thirdly, carrying out alpha-gamma coincidence detection: and when neutrons related to the alpha particles act on gamma generated by the detected object, the gamma is related to the alpha particles, so that only the gamma generated by the neutrons related to the alpha particles is recorded, a gamma energy spectrum corresponding to alpha-gamma is obtained, and most of the gamma generated by neutrons not marked by the alpha is not recorded, so that non-related gamma rays are effectively inhibited, the signal-to-noise ratio is obviously improved, and the detection precision is improved. The utility model discloses according to the speed of 14.1MeV neutron flight and the distance of being examined object to neutron source, can confirm when detecting alpha particle to the time that the neutron passed the examined thing needs, gamma ray is very short (the speed 30cm/ns of gamma ray) from being detected the object to the detector, and data acquisition system selects certain time gate width as the measuring time section as the starting point to the time that detects alpha particle, and other time sections do not measure, and this has just greatly reduced the background.
The fourth step is to analyze the gamma energy spectrum obtained by alpha-gamma coincidence detection: and comparing the C/O and N/O ratio content of C, N, O elements in the detected object with the explosive parameters in the template database according to data analysis, judging, and drawing a conclusion on whether the explosive exists or not.
To sum up, the neutron detection device for the detachable wrapped explosives of the utility model greatly improves the efficiency of the detector and reduces the detection time and the consumption of the neutron source by placing the gamma detector beside the neutron beam outlet hole channel between the detachable neutron source radiation shield and the neutron receiving cavity and abutting against the detected object; the detachable neutron source radiation shielding body adopted by the device is convenient for the detection device to move and use in a manned place, so that nondestructive qualitative detection of suspicious luggage and packages in random places is conveniently realized, and the detection efficiency is high. The device can also detect hidden drugs.
Claims (6)
1. A can dismantle parcel explosive neutron detection device which characterized in that: the detection device comprises a neutron generator, an alpha particle position sensitive detector, a detachable neutron source radiation shield, a neutron receiving cavity, a gamma ray detector and a system control and data acquisition and processing system; the detachable neutron source radiation shield is formed by tightly combining an outer layer, an intermediate layer and an inner layer from outside to inside; the gamma-ray detector is positioned between the neutron generator and the detected object and outside the neutron emitting pore channel so as to improve the detection efficiency; the neutron receiving cavity is positioned behind the neutron emergent pore channel; the neutron generator is placed in the inner layer of the detachable neutron source radiation shielding body, and the bottom surface of the neutron emitting pore channel is horizontal; the object to be detected is placed on the supporting platform, the upper surface of the supporting platform is parallel to the bottom surface of the neutron emitting pore channel and lower than the bottom surface of the neutron emitting pore channel, and the gamma-ray detector is placed below the supporting platform.
2. The apparatus for neutron detection in a removably wrapped explosive according to claim 1, wherein: the neutron generator is a deuterium-tritium neutron generator.
3. The apparatus for neutron detection in a removably wrapped explosive according to claim 1, wherein: the alpha particle position sensitive detector adopts a detection material selected from ZnO scintillators, PIN semiconductors or YAP: ce scintillator.
4. The apparatus for neutron detection in a removably wrapped explosive according to claim 1, wherein: the scintillator of the gamma-ray detector is LaBr3Any one of a scintillator, a BGO scintillator, or a NaI scintillator.
5. The apparatus for neutron detection in a removably wrapped explosive according to claim 1, wherein: the detachable neutron source radiation shield is characterized in that the outer layer is a polyethylene layer, the middle layer is a boron-containing polyethylene layer, and the inner layer is a tungsten layer or an iron layer.
6. The apparatus for neutron detection in a removably wrapped explosive according to claim 1, wherein: the neutron receiving cavity is composed of concave iron, a polyethylene plate and a boron-containing polyethylene plate.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114442182A (en) * | 2022-01-17 | 2022-05-06 | 电子科技大学 | Accompanying alpha particle underground imaging system based on pulse neutrons |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114442182A (en) * | 2022-01-17 | 2022-05-06 | 电子科技大学 | Accompanying alpha particle underground imaging system based on pulse neutrons |
| CN114442182B (en) * | 2022-01-17 | 2023-05-12 | 电子科技大学 | Pulse neutron-based accompanying alpha particle downhole imaging system |
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