CN110764156B - Suspicious object detection device - Google Patents
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- 238000001514 detection method Methods 0.000 title claims abstract description 252
- 238000012545 processing Methods 0.000 claims abstract description 34
- 238000012546 transfer Methods 0.000 claims abstract description 6
- 238000006243 chemical reaction Methods 0.000 claims description 29
- 230000005251 gamma ray Effects 0.000 claims description 27
- 238000005259 measurement Methods 0.000 claims description 19
- 239000013074 reference sample Substances 0.000 claims description 15
- 239000000463 material Substances 0.000 claims description 14
- 239000011159 matrix material Substances 0.000 claims description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 8
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 5
- 239000001257 hydrogen Substances 0.000 claims description 5
- 229910052739 hydrogen Inorganic materials 0.000 claims description 5
- 229910052742 iron Inorganic materials 0.000 claims description 4
- 239000012491 analyte Substances 0.000 claims description 3
- 238000005538 encapsulation Methods 0.000 claims 1
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 28
- 229910052757 nitrogen Inorganic materials 0.000 description 14
- 239000002360 explosive Substances 0.000 description 10
- 238000000034 method Methods 0.000 description 6
- 238000005070 sampling Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000012886 linear function Methods 0.000 description 3
- 239000000523 sample Substances 0.000 description 3
- 238000001228 spectrum Methods 0.000 description 3
- 239000004698 Polyethylene Substances 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000004907 flux Effects 0.000 description 2
- 239000005022 packaging material Substances 0.000 description 2
- -1 polyethylene Polymers 0.000 description 2
- 229920000573 polyethylene Polymers 0.000 description 2
- 239000011241 protective layer Substances 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 238000010200 validation analysis Methods 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000012882 sequential analysis Methods 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
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- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V5/00—Prospecting or detecting by the use of ionising radiation, e.g. of natural or induced radioactivity
- G01V5/20—Detecting prohibited goods, e.g. weapons, explosives, hazardous substances, contraband or smuggled objects
- G01V5/22—Active interrogation, i.e. by irradiating objects or goods using external radiation sources, e.g. using gamma rays or cosmic rays
- G01V5/234—Measuring induced radiation, e.g. thermal neutron activation analysis
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Abstract
The invention discloses a suspicious object detection device, comprising: a detection chamber; a transfer unit for transferring an object to be tested through the inside of the detection chamber; the neutron emission unit is arranged on one side of the detection chamber and is used for emitting neutrons into the detection chamber; the detection module comprises a plurality of detection units and is used for detecting gamma rays generated after the neutron is reacted; the processing unit is used for receiving the detection results of the plurality of detection units and judging whether suspicious objects exist in the object to be detected; and an indicating unit configured to indicate the determination result of the processing unit.
Description
Technical Field
The invention relates to the field of article detection, in particular to a suspicious object detection device.
Background
Nowadays, the form of explosives is more and more concealed, the detection difficulty is higher and higher, some disguised and concealed explosives are difficult to detect through the existing explosive detection instrument, and the development of advanced explosive detection technology and instrument is urgent. Today, detection instruments need to have the ability to detect explosives quickly, conveniently, efficiently, and accurately on-site without unpacking.
When the neutrons react with different elements, gamma rays with different energies can be generated, and meanwhile, the neutrons have the characteristics of strong penetrability, high accuracy, high detection sensitivity and low false alarm rate. The detection of explosives using neutrons enables explosives to be detected without damaging the article.
Therefore, there is a need in the art for a suspicious object detection apparatus with high detection accuracy, low false alarm rate, high detection efficiency and short time consumption.
Disclosure of Invention
It is an object of an embodiment of the present invention to provide a suspicious object detecting apparatus, including: a detection chamber; a transfer unit for transferring an object to be tested through the inside of the detection chamber; the neutron emission unit is arranged on one side of the detection chamber and is used for emitting neutrons into the detection chamber; the detection module comprises a plurality of detection units and is used for detecting gamma rays generated after the neutron is reacted; the processing unit is used for receiving the detection results of the plurality of detection units and judging whether suspicious objects exist in the object to be detected; and an indicating unit configured to indicate the determination result of the processing unit.
According to the embodiment of the invention, the neutron emitting unit further comprises a shielding unit for shielding neutrons emitted by the neutron emitting unit.
According to an embodiment of the invention, the processing unit is arranged to: before the object to be detected is detected, receiving detection results of the plurality of detection units on the first characteristic gamma rays and the second characteristic gamma rays; calibrating each of the plurality of detection units based on the detection results of the first characteristic gamma ray and the second characteristic gamma ray; fitting the plurality of calibrated detection units based on the detection result of the first characteristic gamma ray; wherein the first characteristic gamma ray is obtained based on a reaction of the neutron with a shielding material of the shielding unit, and the second characteristic gamma ray is obtained based on a reaction of the neutron with an encapsulating material of the detection module.
According to an embodiment of the invention, the neutrons react with hydrogen elements in the shielding material; the neutrons react with iron in the encapsulating material.
According to an embodiment of the invention, the first characteristic gamma ray comprises a first characteristic peak and the second characteristic gamma ray comprises a second characteristic peak, the processing unit being arranged to: and determining the relation between the address and the energy of each detection unit based on the address and the energy corresponding to the first characteristic peak and the address and the energy corresponding to the second characteristic peak.
According to an embodiment of the invention, the processing unit is arranged to: unifying the relationship between the addresses and the energy of the detection units into a specific relationship.
According to an embodiment of the invention, the processing unit is arranged to: acquiring conversion values based on the measurement values of the detection units and the conversion criteria; and comparing the conversion value with a first threshold value and a second threshold value to judge whether the suspicious object exists in the object to be detected.
According to the embodiment of the invention, the conveying unit is arranged to enable the target area of the object to be detected to be placed at the target position with the most intensive neutrons in the detection chamber.
According to an embodiment of the invention, the formula of the scaling criterion is as follows:
wherein L is1Representing the scaled value, n representing the number of detection cells, xiDenotes the measured value, x, of the ith detection cellEiDenotes a reference measurement value, x, determined by the i-th detecting unit when a reference sample at the target position is detected in advanceBiAnd an accumulated value representing the measured background value of the ith detection unit in the predetermined time.
According to an embodiment of the invention, the reference measurement value is determined by a response matrix of the plurality of detection units, the response matrix indicating a relation between the measurement value of the reference sample and the detection position.
According to an embodiment of the invention, the processing unit is arranged to: determining that there is no suspect based on the scaled value being less than the first threshold.
According to an embodiment of the invention, the processing unit is arranged to: further calculating a first summation result and a second summation result of the measurement values of the plurality of detection units based on the scaled value being greater than the second threshold value, and comparing; wherein the presence of a suspicious object is determined based on the first summation result being greater than or equal to the second summation result; determining that there is no suspect based on the first summation result being less than the second summation result.
According to an embodiment of the invention, the first summation result is calculated as follows:
d1＝∑xiwEi
the second summation result is calculated as follows:
d2＝∑xi
wherein d is1Representing the result of the first summation, d2Denotes the second summation result, xiDenotes the measured value of the i-th detection unit, wEiIs determined by the signal-to-noise ratio of each detection unit and the number of detection units.
According to an embodiment of the invention, the first threshold is calculated as follows:
the second threshold is calculated as follows:
wherein, c0Denotes a first threshold value, c1Represents the second threshold, alpha represents the false alarm rate, and beta represents the false detection rate.
According to an embodiment of the invention, the processing unit is arranged to: acquiring a conversion value based on detection values of the plurality of detection units in a unit time, and judging whether the conversion value is smaller than the first threshold value or larger than the second threshold value; if yes, judging that a suspicious object exists in the object to be detected or the suspicious object does not exist in the object to be detected; if not, judging whether the detection result is smaller than the first threshold value or larger than the second threshold value again according to the judging mode based on the detection results of the plurality of detection units in another unit time; and when the detection result does not meet the effective condition after the judgment is carried out for the preset times, judging whether a suspicious object exists in the object to be detected or not based on another judgment criterion.
According to an embodiment of the present invention, the determining whether there is a suspicious object or not in the object to be tested based on another determination criterion includes: determining that there is no suspect based on the scaled value being less than 0; determining that a suspicious object exists based on the converted value not being less than 0.
By adopting the technical scheme, the invention mainly has the following technical effects:
1. the object to be detected is placed at the target position with the densest neutron density for detection, so that the detection effect can be improved, the accuracy of the detection result is improved, the detection time is effectively shortened, and the detection efficiency is improved;
2. by using the conversion criterion, the measurement values of the plurality of detection units can be converted into conversion values, and by comparing the conversion values with the first threshold value and the second threshold value, whether suspicious objects exist in the target area can be judged;
3. the detection module can be calibrated through the first characteristic gamma ray and the second characteristic gamma ray, so that the reliability of the detection result of the detection module is improved, and the consistency among different detection units is realized;
4. the detection process is divided into a plurality of unit times to be carried out for a plurality of times, and the detection result of each time is judged, so that the detection time can be flexibly determined according to different conditions of different objects to be detected, the detection time can be shortened, the detection efficiency can be improved, and the utilization rate of the neutron tube can be improved.
Drawings
Fig. 1 is a schematic view of a suspect detection apparatus according to one embodiment of the present invention;
fig. 2 is a schematic diagram of the operation of a suspect detection apparatus in accordance with one embodiment of the present invention;
fig. 3 is a schematic diagram of a suspicious object detecting apparatus according to another embodiment.
In the figure, 1, a detection chamber; 2. a transfer unit; 3. a neutron emitting unit; 4. a detection module; 5. a processing unit; 6. an indicating unit; 7. an object to be tested; 8. a power source; 81. a drive unit; 9. a neutron detector.
Detailed Description
The following description of the embodiments of the present invention is provided in connection with the accompanying drawings.
The invention discloses a suspicious object detection device, which is a device for judging whether a suspicious object exists in an object to be detected by detecting characteristic gamma rays of nitrogen elements through the reaction of neutrons and the nitrogen elements in the suspicious object. Specifically, referring to fig. 1 and 2, the suspicious object detecting apparatus includes: a detection chamber 1; a transport unit 2 for transporting an object 7 to be tested through the interior of the detection chamber 1; the neutron emitting unit 3 is arranged on one side of the detection chamber 1 and is used for emitting neutrons into the detection chamber 1; the detection module 4 comprises a plurality of detection units and is used for detecting gamma rays generated after neutron reaction; the processing unit 5 is configured to receive the detection results of the plurality of detection units and judge whether suspicious objects exist in the object to be detected 7; and an indicating unit 6 for indicating the judgment result of the processing unit 5.
Preferably, the neutron emitted by the neutron emitting unit 3 in this embodiment may be a fast neutron of 2.5MeV, the fast neutron is moderated to become a thermal neutron, and the thermal neutron strikes N to generate a thermal neutron capture reaction, so as to generate a characteristic gamma ray of 10.83 MeV.
n+14N→15N+10.83MeV
The nitrogen content of explosives can be determined using the characteristic gamma ray of N10.83 MeV from the nuclear reaction N (N, γ).
The detection module 4 can be composed of 11 nai (tl) crystal scintillation detectors of Φ 150 × 100mm, each detector has 3 cable connectors: the high-voltage electric connector is used for connecting a power supply of the photomultiplier, and the preamplifier voltage connector and the preamplifier module signal connector are arranged on the detector shell. In order to prolong the service life of the detection module 4, preferably, a protective layer for avoiding neutron radiation is arranged around the scintillation detector in the embodiment, the protective layer is formed by compression-bonding LiF powder capable of efficiently absorbing thermal neutrons, and in order to ensure that the detection module 4 can also normally work under a lower temperature condition, a heater is arranged on the detection module 4, and the heater is connected with a thermocouple. A plurality of detection cells may be provided at the side or above the detection chamber 1.
The suspect detection apparatus of the present invention may further comprise a neutron detector 9 for detecting the operating condition of the neutron emitting unit 3. The processing unit 5 in this embodiment may include 12 ADC boards, PMT power boards, low voltage power boards, and a detection board. One of the ADC boards is used to receive the signal of the neutron detector 9, and the other 11 ADC boards are used to receive the detection signal of the detection unit. The ADC can convert the detected analog signal into a digital signal and then form a spectrum. The suspect detection apparatus may further comprise a power supply 8 for powering the entire apparatus.
After an object to be detected enters the detection chamber 1, the object to be detected is transmitted to the inside of the detection chamber through the transmission unit 2, the object to be detected is irradiated by neutrons emitted by the neutron emission unit 3, nitrogen elements in suspicious objects react to generate characteristic gamma rays of 10.83MeV, the detection unit detects the characteristic gamma rays, detection results are transmitted to the processing unit 5 to be processed, whether the object to be detected contains the suspicious objects or not is judged, and the judgment results are indicated through the indicating unit 6. The indication unit 6 may be a display screen, for example, may display "detected explosives" in red and "undetected explosives" in green. In other embodiments, the indication unit 6 may also be a voice indication device or the like. The conveying unit 2 may include a conveying belt and a driving wheel, which may be driven by a driving unit 81, and the driving unit 81 may include a motor.
The detection apparatus may further include a shielding unit for shielding neutrons emitted by the neutron emitting unit 3.
In one embodiment, the processing unit 5 may be arranged to: prior to the detection of the analyte 7,
receiving detection results of the plurality of detection units on the first characteristic gamma rays and the second characteristic gamma rays;
calibrating each of the plurality of detection units based on the detection results of the first characteristic gamma ray and the second characteristic gamma ray; and
fitting the plurality of calibrated detection units based on the detection result of the first characteristic gamma ray;
wherein the first characteristic gamma ray is obtained based on a reaction of the neutron with a shielding material of the shielding unit, and the second characteristic gamma ray is obtained based on a reaction of the neutron with an encapsulating material of the detection module 4.
The first characteristic gamma ray and the second characteristic gamma ray generated by the reaction of the neutrons with the shielding material of the shielding unit and the packaging material of the detection module 4 respectively are used for calibrating each detection unit, the accuracy of the measurement result of each detection unit can be ensured, the detection unit is calibrated without disassembling a device, the operation is convenient, and the limitation of crystal materials of the detection unit is avoided. In addition, the first characteristic gamma ray is used for fitting the plurality of calibrated detection units, so that the consistency among different detection units can be realized, and the accuracy of subsequent data processing and identification judgment can be favorably ensured.
Specifically, the shielding unit is usually made of a large amount of shielding materials such as polyethylene and B-containing polyethylene, and the shielding materials contain a large amount of hydrogen elements, and neutrons react with the hydrogen elements to generate first characteristic gamma rays, where the first characteristic gamma rays include a first characteristic peak, and the energy corresponding to the first characteristic peak is 2.23 MeV. The detection module 4 is generally packaged by using stainless steel, the packaging material contains iron, neutrons react with the iron to generate second characteristic gamma rays, the second characteristic gamma rays include a second characteristic peak, and the energy corresponding to the second characteristic peak is 7.6 MeV.
The abscissa in the energy spectrogram represents a track address, and the track address and the energy have a certain corresponding relation. When the working performance of the detection unit is affected by the environment, the corresponding relation changes, thereby causing the problem of energy spectrum shift. Therefore, before the detection by the detection unit, the relationship between the current track address and the energy needs to be determined. The relationship between the track address and the energy may be a linear function relationship, determined by a slope and a constant. The processing unit 5 is arranged to: and determining the relation between the address and the energy of each detection unit based on the address and the energy corresponding to the first characteristic peak and the address and the energy corresponding to the second characteristic peak. Thus, based on the two known points, the straight line corresponding to the linear function, that is, the slope and constant of the linear function can be determined.
Because the relationship between the addresses and the energies of the detecting units is different, in order to facilitate the subsequent analysis of a plurality of detecting results, the relationship between the addresses and the energies of the detecting units needs to be unified into a specific relationship, that is, the plurality of detecting units are fitted, so that the energy spectrum curves detected by the detecting units are displayed in the same coordinate system. In an embodiment of the present invention, the processing unit 5 may be configured to: and fitting based on the detection result of the first characteristic gamma ray, namely fitting each detection unit based on the position of the first characteristic peak (hydrogen peak) so that the first characteristic peaks in the energy spectrogram measured by each detection unit are coincident with each other.
After the calibration of the detection module 4 is completed, the detection of the object to be detected 7 may be started. Before the suspicious object detection device is used for detection, the object to be detected can be preliminarily detected, the target area in the object to be detected, which is possibly provided with the suspicious object, can be judged by the preliminary detection, and other areas are filtered, and the detection module 4 only needs to detect the target area, so that the detection efficiency is improved, partial interferents can be eliminated, and the false alarm rate is reduced; accordingly, the distribution range of neutrons for detection is reduced, the neutron flux is increased, and the detection effect is improved, for example, the neutron field can be distributed in only half of the area of the detection chamber 1.
In an embodiment of the present invention, the transfer unit 2 may be configured such that the target region of the object 7 is placed at a target position where neutrons are most dense in the detection chamber 1. For example, neutrons may be intensively distributed at a central position of the neutron field, that is, the neutron flux at the central position is the largest, and after the preliminary-detected object 7 to be detected enters the detection chamber, the target area is placed at the central position for detection.
In some embodiments, the processing unit 5 may be arranged to:
acquiring conversion values based on the measurement values of the detection units and the conversion criteria; and
and comparing the converted value with a first threshold value and a second threshold value to judge whether a suspicious object exists in the object 7 to be detected.
Preferably, after the measured values are obtained by the plurality of detection units, before the conversion values are obtained, in order to facilitate the conversion of the conversion values, the reference sample containing a predetermined amount of nitrogen element is sequentially placed in different positions of the detection area where the neutron field is located for detection, specifically, the detection area may be divided into a plurality of cells, the reference sample is sequentially moved in the plurality of cells, thermal neutron stream irradiation is performed on the reference sample, the detection result is recorded, a response matrix of the plurality of detection units is obtained based on the placement position of the reference sample and the detection result of the plurality of detection units on the reference sample, and the rank of the response matrix is the number of the detection units. Wherein, the detection result of the reference sample needs to remove the measurement background value, and the measurement background value can comprise background radiation. The response matrix indicates a relationship between the measurement value of the reference sample and the detection position, by which the reference measurement value measured by the detection unit when the reference sample is moved to the target position in the detection area for detection can be acquired.
The formula of the conversion criterion in this embodiment is as follows:
in the formula, L1Representing the scaled value, n representing the number of detection cells, xiDenotes the measured value, x, of the ith detection cellEiDenotes a reference measurement value (calculated from a response matrix) determined by the i-th detecting unit when the reference sample at the target position is detected in advance, xBiAnd an accumulated value representing the measured background value of the ith detection unit in the predetermined time.
Wherein x isBiCan be calculated by the following formula:
in the formula, xBiDenotes an average background value of the detection units, and t denotes a predetermined time.
xEiCan be calculated by the following formula:
xEi＝Mi(x,y)mpt
wherein M isiRepresenting a response matrix, (x, y) representing a point in the response matrix, i.e. a detection position; m represents the mass of nitrogen in the reference sample; p represents the power of a neutron source for providing neutrons; t represents a predetermined time.
Calculate L1Then, it is compared with a first threshold value and a second threshold value, the first threshold value may be smaller than the second threshold value, and the first threshold value and the second threshold value may be calculated by the following formula:
in the formula, c0Represents a first threshold value; c. C1Represents a second threshold; α represents a false positive rate (false positive may represent, for example, an error when the source of nitrogen is not a suspect but another item but is judged to be suspect); beta represents the false detection rate (false detection may mean, for example, that the detection result of the nitrogen element by the detection unit is false).
Wherein, alpha and beta are both values set by an operator according to the detection requirement, when L is1Is less than c0Then, the object to be detected can be determined not to contain the suspicious object; when L is1Greater than c1In order to eliminate the detection interference of the non-suspicious object in the object to be detected, a first summation result and a second summation result of the measurement values of the plurality of detection units need to be further calculated and further judged, and a specific calculation formula is as follows:
d1＝∑xiwEi
d2＝∑xi
in the formula (d)1Representing a first summation result; d2Representing a second summation result; x is the number ofiDenotes the measured value of the i-th detection unit, wEiIndicating the quality of the standard, which is determined by the signal-to-noise ratio of each detection unit and the number of detection units.
W in the above formulaEiThis can be calculated by:
in the formula,
representing the signal-to-noise ratio of the i-th detection unit, n representing the number of detection units,
indicating that the ith detection cell is in advanceThe average value of the measured values when the reference sample at the target position is detected first represents the average value of the background values of the i-th detection unit.
The nitrogen density can be known by comparing the first summation result and the second summation result. In the embodiment of the present invention, if d1Is greater than or equal to d2Then it can be determined that the measured nitrogen is from the suspicious object (the distribution of nitrogen is more concentrated), i.e. the suspicious object is contained in the object to be measured; if d is1Is less than d2It can be determined that the measured nitrogen originates from interferents (where the distribution of nitrogen is relatively diffuse) and the test object does not contain suspicious species. Therefore, the interference of nitrogen elements in the non-suspicious object on the detection device can be effectively eliminated, the accuracy of detecting the suspicious object is improved, and the stability of the detection device is enhanced.
In some embodiments, the processing unit 5 may be arranged to:
obtaining a converted value L based on detection values of the plurality of detection units in a unit time1And determining the converted value L1Whether or not it is less than the first threshold value c0Or if it is greater than the second threshold value c1；
If yes, judging that the suspicious object exists or does not exist in the object to be detected 7;
if not, based on the detection results of the detection units in another unit time, whether the detection results are smaller than the first threshold value c is judged again according to the judging mode0Or if it is greater than the second threshold value c1；
When the detection result does not meet the validation condition after the predetermined times of judgment, the existence or nonexistence of the suspicious object in the object 7 is judged based on another judgment criterion.
The invention applies the thought of sequential statistics to the detection of the object 7 to be detected, and the sequential statistics refers to that: the sampling stage does not fix the sample capacity in advance, but gives a group of rules for stopping sampling, the result is observed immediately when a sample is newly extracted, whether the sampling is stopped and the statistical inference is carried out or whether the new sample is continuously extracted and observed is judged according to the result until the sampling is finally stopped, and the inference is made according to the result. The invention divides the whole detection time of the prior art into a plurality of unit times, only detects the unit time each time, determines whether to detect again according to the detection result, and the detection times are the most of the number of all divided time segments. That is, for each analyte, detection is performed for at most the entire time, and detection is performed for at least one unit time. The detection process is carried out for multiple times in multiple unit time, and the detection result of each time is judged, so that the detection time can be flexibly determined according to different conditions of different objects to be detected, excessive time does not need to be delayed for the condition that the detection result can be quickly judged, for example, the detection less than the preset number of times can be carried out to make judgment, and the detection is finished. Therefore, compared with the prior art, the detection time can be shortened, the detection efficiency can be improved, and the utilization rate of the neutron tube can be improved.
When the detection is performed for a predetermined number of times, if the value is converted to L1Is still at the value of c0And c1In between, that is, the detection result still does not satisfy the validation condition, at this time, it may be determined that there is a suspicious object or there is no suspicious object in the object to be detected 7 based on another determination criterion, and the detection is ended. In one embodiment, L may be1Is compared with 0 if L1If less than 0, it can be determined that no suspicious object exists in the object 7, and if L is less than 01If it is not less than 0, it can be determined that the suspicious object exists in the object to be measured 7.
By adopting the technical scheme, the sequential analysis method is combined with the process of detecting the suspicious object by the neutrons, the whole detection time in the prior art is divided into a plurality of unit times, single detection is carried out in the unit time, and the result of the single detection is analyzed. If the result of single detection meets the effective condition, judgment can be made, and detection is finished, so that the detection time can be effectively saved; if the detection result does not meet the effective condition after the detection is carried out for the preset times, the other set of standard is used for judging whether the object to be detected contains the suspicious object, so that the detection reliability is ensured. The detection time is shortened, the use efficiency of the neutron tube can be effectively improved, and the use cost of the neutron tube is reduced.
The use method of the detection device of the embodiment is as follows:
an operator turns on a power supply 8 of the detection device, the detection device is started and carries out self-detection work and calibration work, after the self-detection work and the calibration work are completed, the operator controls an object to be detected to enter the detection chamber 1 for suspicious object detection, a detection result is transmitted to the processing unit 5, the processing unit 5 can process the detection result and transmit the processing result to the indicating unit 6, and the indicating unit 6 informs the operator of the suspicious object detection result.
The above embodiments are only for illustrating the invention and are not to be construed as limiting the invention, and those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention, therefore, all equivalent technical solutions also belong to the scope of the invention, and the scope of the invention is defined by the claims.
Claims (12)
1. A suspect detection apparatus, comprising:
a detection chamber;
a transfer unit for transferring an object to be tested through the inside of the detection chamber;
the neutron emission unit is arranged on one side of the detection chamber and is used for emitting neutrons into the detection chamber;
the detection module comprises a plurality of detection units and is used for detecting gamma rays generated after the neutron is reacted;
the processing unit is used for receiving the detection results of the plurality of detection units and judging whether suspicious objects exist in the object to be detected; and
an indicating unit configured to indicate a determination result of the processing unit;
the processing unit is configured to:
acquiring conversion values based on the measurement values of the detection units and the conversion criteria; and
comparing the converted value with a first threshold value and a second threshold value to judge whether a suspicious object exists in the object to be detected;
the processing unit is configured to:
further calculating a first summation result and a second summation result of the measurement values of the plurality of detection units based on the scaled value being greater than the second threshold value, and comparing; wherein,
determining that a suspicious object exists based on the first summation result being greater than or equal to the second summation result;
determining that there is no suspect based on the first summation result being less than the second summation result;
the first summation result is calculated as follows:
d1＝∑xiwEi
the second summation result is calculated as follows:
d2＝∑xi
wherein d is1Representing the result of the first summation, d2Denotes the second summation result, xiDenotes the measured value of the i-th detection unit, wEiIs determined by the signal-to-noise ratio of each detection unit and the number of detection units.
2. The apparatus of claim 1, further comprising a shielding unit for shielding neutrons emitted from the neutron emitting unit.
3. The apparatus of claim 2, wherein the processing unit is configured to: prior to the detection of the analyte,
receiving detection results of the plurality of detection units on the first characteristic gamma rays and the second characteristic gamma rays;
calibrating each of the plurality of detection units based on the detection results of the first characteristic gamma ray and the second characteristic gamma ray; and
fitting the plurality of calibrated detection units based on the detection result of the first characteristic gamma ray;
wherein the first characteristic gamma ray is obtained based on a reaction of the neutron with a shielding material of the shielding unit, and the second characteristic gamma ray is obtained based on a reaction of the neutron with an encapsulation material of the detection module;
the first characteristic gamma ray comprises a first characteristic peak and the second characteristic gamma ray comprises a second characteristic peak, the processing unit being arranged to:
and determining the relation between the address and the energy of each detection unit based on the address and the energy corresponding to the first characteristic peak and the address and the energy corresponding to the second characteristic peak.
4. The apparatus of claim 3, wherein the neutrons react with hydrogen elements in the shielding material; the neutrons react with iron in the encapsulating material.
5. The apparatus of claim 1, wherein the processing unit is configured to:
unifying the relationship between the addresses and the energy of the detection units into a specific relationship.
6. The apparatus of claim 1, wherein the transfer unit is configured such that the target area of the object is placed at a target position where neutrons are most dense within the detection chamber.
7. The apparatus of claim 6, wherein the scaling criterion is formulated as follows:
wherein L is1Representing the scaled value, n representing the number of detection cells, xiDenotes the measured value, x, of the ith detection cellEiDenotes a reference measurement value, x, determined by the i-th detecting unit when a reference sample at the target position is detected in advanceBiMeans for accumulating the measured background value of the i-th detecting unit in a predetermined timeAnd (6) evaluating.
8. The apparatus of claim 7, wherein the reference measurement is determined from a response matrix of the plurality of detection units, the response matrix indicating a relationship between the measurement of the reference sample and the detection location.
9. The apparatus of claim 1, wherein the processing unit is configured to:
determining that there is no suspect based on the scaled value being less than the first threshold.
10. The apparatus of claim 1,
the first threshold is calculated as follows:
the second threshold is calculated as follows:
wherein, c0Denotes a first threshold value, c1Represents the second threshold, alpha represents the false alarm rate, and beta represents the false detection rate.
11. The apparatus of claim 1, wherein the processing unit is configured to:
acquiring a conversion value based on detection values of the plurality of detection units in a unit time, and judging whether the conversion value is smaller than the first threshold value or larger than the second threshold value;
if yes, judging that a suspicious object exists in the object to be detected or the suspicious object does not exist in the object to be detected;
if not, judging whether the detection result is smaller than the first threshold value or larger than the second threshold value again according to the judging mode based on the detection results of the plurality of detection units in another unit time;
and when the detection result does not meet the effective condition after the judgment is carried out for the preset times, judging whether a suspicious object exists in the object to be detected or not based on another judgment criterion.
12. The apparatus of claim 11, wherein said determining the presence or absence of a suspicious object in the object based on another determination criterion comprises:
determining that there is no suspect based on the scaled value being less than 0;
determining that a suspicious object exists based on the converted value not being less than 0.
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