Classifications

• • G—PHYSICS
  • 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
  • G01V5/281—Detecting prohibited goods, e.g. weapons, explosives, hazardous substances, contraband or smuggled objects detecting special nuclear material [SNM], e.g. Uranium-235, Uranium-233 or Plutonium-239
• • G—PHYSICS
  • 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
  • G01V5/224—Multiple energy techniques using one type of radiation, e.g. X-rays of different energies

Definitions

• the present invention relates to the detection of the presence in a load of suspect objects containing one or more high atomic weight materials, such as materials likely to have a nuclear activity.
• X-ray scanners To detect the presence of suspicious objects such as contraband, weapons, explosive devices, it is known to use X-ray scanners to develop an image by transparency of the contents of the load. Such devices are used for example in airports to control passenger baggage but they are also used in various checkpoints, particularly in customs to control the contents of containers or the contents of truck trailers or any vehicles. In general, these X-ray scanners provide a grayscale image of the contents of the charges, and the recognition of the objects contained in the charge is performed by an operator viewing the images provided by the scanner.
• some scanners including scanners for examining passenger baggage, are able to perform so-called “low energy” discrimination that relies on the photoelectric effect by using radiation with energies less than 150 KeV.
• This "low energy” discrimination makes it possible to propose to the observer a classification of objects by categories of atomic number and can thus help to detect highly organic materials, such as those contained in explosives or contrary to atomic number materials.
• highly organic materials such as those contained in explosives or contrary to atomic number materials.
• nuclear products especially SNMs ("Special Nuclear Materials").
• Some scanners may also perform "high energy” discrimination, based on the creation of electron-positron pairs, using radiation with energies above 1 MeV, with the same purpose as energy-discriminating scanners. but adapted to examine larger objects than in the previous case.
• Discrimination by the atomic number can be used to present to the operator images on which are superimposed on the one hand the gray-scale view in transparency, and on the other hand colors indicating the numbers. atomic.
• This discrimination which makes it possible to classify the materials, however has the disadvantage of not distinguishing, among the high atomic number materials, those which are potentially suspect because of the danger which they represent or of any other criterion and those which are innocuous.
• the high-level, innocuous level materials include lead, which can be found in welds and diving weights, tungsten, which can be found in high-strength parts, and tin. can be found in tableware, neodymium found in magnets, or cadmium found in batteries.
• the subject of the invention is a method for detecting in a load the presence of suspect objects containing at least one material with a given atomic weight, according to which the charge is subjected to at least a first X radiation having a first spectrum. and determining an atomic number class to which belong the materials of which the charge traversed by the X-radiation by high energy discrimination is constituted.
• at least one y or neutron radiation spontaneously emitted by the charge, a class of spontaneous radiation emission y and / or neutron of the material of which the charge is constituted from the measurement of spontaneous radiation is determined and a class of interest of the material of the charge is determined from the class atomic number and the determined spontaneous radiation class.
• the charge can be subjected to neutron radiation whose absorption rate is measured to contribute to said determination of the atomic number class.
• the radiation absorption rate and the atomic number class are determined at a plurality of areas of the load so as to form a transparent image of the load distribution of the detected interest classes.
• the load is scrolled, on the one hand, between at least one X-ray emitter, and possibly a transmitter of neutrons, and a plurality of X-ray detectors, and optionally a plurality of neutron detectors, disposed in at least one line extending in an analysis plane (P) traversed by the direction of movement of the charge, and, on the other hand, with respect to a y-ray and / or neutron detector adapted to perform a sectional analysis, measurements of X-ray absorption corresponding to two spectra and measurements of spontaneous radiation y or neutron are made.
• P analysis plane
• the X-ray absorption and spontaneous radiation y or neutron absorption measurements are combined in such a way that read a map of the class of interest of the materials of which the load is made.
• At least one X-ray radiation can have a maximum energy sufficient to cause photofission and, in addition, a neutron emission measurement resulting from photofission is carried out and the evaluation of the atomic number class is used. the emission of spontaneous radiation y or neutron and the evaluation of neutron emission resulting from photofission to determine the class of interest of the material of the charge.
• the charge can be passed between a plurality of radiation emitters and a plurality of detectors, so as to perform a plurality of detections according to a plurality of analysis planes and / or analysis directions.
• At least one image of the content of the load and the distribution of the classes of interest that is made available to an operator can be developed.
• an alert signal is emitted, for example sound and / or visual.
• the invention also relates to a device for implementing said method which comprises at least one X-ray emitter adapted to emit X-rays with a maximum energy higher than 1 MeV, to enable high energy discrimination, at least an X-ray detector, and a control and processing module connected to the X-ray emitter and to each X-ray detector.
• the device further comprises at least one y or neutron radiation detector connected to the X-ray detector. order and processing.
• control and processing module is adapted so that the X-ray emissions are carried out by pulses separated by sufficient time intervals to carry out measurements of radiation emission y and to neutralize the radiation detector y during the emissions. X-ray and activate it during the intervals between X-ray emissions.
• the X-ray detectors are arranged in a column, facing the X-ray emitter, and the device comprises means for ensuring a relative displacement of a load to be analyzed and means for transmitting X-rays. and detecting X, y or neutron radiation, and means for associating the charge displacement and the radiation measurements so as to associate the y or neutron radiation detection and the detection of a given atomic number to generate, the if necessary, an alarm and, possibly, at least one image of the distribution in the load of the classes of interest of the materials of the load.
• the device can be adapted in particular for inspecting a container or a truck trailer, or a vehicle.
• FIG. 1 is a diagrammatic sectional view of an installation intended to scanise the contents of the trailer of a truck in order to detect in the load of the truck the possible presence of suspicious objects;
• FIG. 2 represents a timing in the X-ray emission and the y-ray emission time using a scanner represented in FIG. 1;
• FIG. 3 shows, seen from above, a first embodiment of a truck scanner as shown in Figure 1;
• FIG. 4 represents, seen from above, a second embodiment of a scanner as represented in FIG. 1.
• the invention consists in the combination of a transparency examination by radiations making it possible to evaluate the atomic number materials crossed, on the one hand, and a detection of spontaneous or natural radiation emitted by materials, on the other hand.
• the transparency examination always includes the use of high energy X-rays to perform high energy discrimination of the atomic number. This method of high energy discrimination is known to those skilled in the art.
• the examination may further include a transparency examination by X-ray at higher energy, or by neutron radiation.
• the spontaneous radiation detected may be either y-radiation or spontaneous neutron radiation.
• the presence of these radiations, the energy spectrum of which may, if appropriate, be determined, combined with information on an atomic number class, makes it possible to determine whether it is probable or not that the charge examined contains, for example, a potentially dangerous nuclear material, or any other material of interest.
• spontaneous radiation in the context of the invention, is meant both radiation resulting from the radioactivity natural load that a radiation that would be induced by the X-ray irradiation or neutron load.
• FIG 1 there is shown in front a scanner control installation of the contents of a truck.
• the installation generally marked by 1, intended to control the contents of the truck 2's load, consists of a device comprising on the one hand an X-ray emitter 3 and on the other hand a measuring gantry 4 consisting of a plurality of X-ray detectors 5 arranged in columns facing the X-ray emitter 3 and one or more radiation detectors 6 each consisting of a scintillator and a photomultiplier.
• the X-ray emitter 3 and the measuring gantry 4 are separated by a circulation zone 9 of the truck 2.
• the X-ray emitter consists of a target, for example made of tungsten, and a transmitter of electrons consisting of, for example, an electron accelerator or any other type of electron beam generator, and includes means for collimating the X-ray beams so that they are contained in a P analysis plane
• the electron beam generator is adapted to be able to generate accelerated electron beams at a voltage of 2 megavolts (MV), and accelerated electron beams at voltages of 6 MV so as to be able to generate, on the one hand, X-ray beams with a maximum energy of 6 MeV and, on the other hand, X-ray beams with a maximum energy of 2 MeV.
• MV megavolts
• the X-ray emitter 3 is connected to a control module 7 which itself is also connected on the one hand to all the X-ray detectors 5, and on the other hand to the y-ray detector 6.
• control module is also connected to a viewing station 8 of the contents of the truck.
• the column 4 of X-ray detectors 5 and the radiation detector 6 are arranged side by side, so that only the column of X-ray detectors is located opposite the
• only the X-ray detector column 5 is located opposite the ray generator.
• X, and the detector 6 'of spokes y is located apart and, for example, remote at the end of the control installation.
• the truck can move in front of the X-ray generators by crossing the analysis plane P.
• the analysis plane P it is possible to use a device that has not been represented. in the figure but that the skilled person knows.
• the device comprises a tray on which a truck is placed, the tray being motorized so as to be able to move in front of the X-ray generator, and of which, preferably, the movements are recorded in real time, this recording of displacements being communicated to the control module 7.
• the truck is stationary and the scanning device consisting of the X-ray emitter 3 and x-ray detectors 5 and radiation y 6 is collected. on a gantry crane that can move along the truck.
• the movements of the gantry are preferably recorded in real time and communicated to the control module 7.
• a relative movement of the truck and the scanning device is carried out so as to scrolling the entire load between the X-ray emitter and the X and y radiation detectors and successively subjecting the truck to X-ray bombardment having a maximum energy level of 2 MeV, and X-ray radiation with a maximum energy of 6 MeV, and using X-ray sensors 5, the amount of transmitted x-rays is measured on the one hand for beams with maximum energy of 2 MeV and, on the other hand, for beams with maximum energy of 6 MeV.
• the high and low energy X-ray beams are alternated.
• two separate X-ray sources one high-energy, the other low-energy, may be provided.
• the radiation y is recorded which is emitted by the load of the truck.
• This radiation y is recorded in slices that pass in front of the detector and the intensity of the radiation emitted y is associated with the relative position of the truck and the scanning device at the moment when the measurement is made.
• an indication of emission of radiation y is known in themselves to those skilled in the art.
• the radiation detector y 6, 6 ' can be, as shown in FIG.
• the scintillator receives significant X-ray fluxes.
• the X-ray flux received by the scintillator is much lower.
• the target is illuminated by a succession of high-energy X-ray peaks 10 and by a succession of lower maximum energy X-ray peaks 11.
• the emissions of X-ray peaks at high and lower energies are performed during periods 12 during which, for example, the power supply of the photomultipliers of the y-radiation detector is cut off to render it inactive and thus to perform the above-mentioned neutralization.
• the power supply of the photomultiplier of the radiation detector y is reactivated so as to be able to measure y-radiation. So, during periods 12, the X-ray absorption measurements are carried out and during the intermediate periods 13, Y-radiation measurements which are not disturbed by the X-ray emissions are carried out.
• the transparency analysis is carried out by X-ray.
• the charge is subjected to neutron radiation, which is added to the above-mentioned X-ray radiation.
• neutron radiation which is added to the above-mentioned X-ray radiation.
• the determination of the atomic number class is made by exploiting the absorptions of both types of radiation by the charge.
• the person skilled in the art knows how to choose the means of analysis in transparency that are best suited to each case.
• neutron detectors known per se are used.
• a neutron radiation measuring means for measuring the neutron radiation resulting from a photonic excitation.
• an X-ray emitter capable of emitting radiation whose maximum energy is at least 9 MeV and there is, next to the X-ray detectors, a neutron detector.
• This complementary process is based on the physical phenomenon of photofission which corresponds to the fission of certain materials resulting from the bombardment by high energy X-rays, which generates a neutron emission.
• the device which has just been described comprises a detector of ⁇ -rays extending on one side of the passage zone of the trucks to be inspected.
• This y-ray detector has a large surface so as to detect relatively weak radiation.
• the device which has just been described is a device which makes it possible to examine the contents of a truck, but it is also possible to provide devices for examining the contents of trailers or containers such as those on board ships, or any other charge placed in a container or in bulk.
• the device comprises means for relative displacement of the load to be controlled and the X-ray emitter.

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• Physics & Mathematics (AREA)
• High Energy & Nuclear Physics (AREA)
• Life Sciences & Earth Sciences (AREA)
• General Life Sciences & Earth Sciences (AREA)
• General Physics & Mathematics (AREA)
• Geophysics (AREA)
• Analysing Materials By The Use Of Radiation (AREA)
• Measurement Of Radiation (AREA)

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• 2008
  • 2008-07-04 FR FR0854551A patent/FR2933498B1/fr active Active
• 2009
  • 2009-07-06 RU RU2011103925/28A patent/RU2510521C2/ru active
  • 2009-07-06 EP EP09772762A patent/EP2297597A2/de not_active Ceased
  • 2009-07-06 US US13/002,563 patent/US20110193711A1/en not_active Abandoned
  • 2009-07-06 CA CA2729861A patent/CA2729861C/fr active Active
  • 2009-07-06 WO PCT/FR2009/051336 patent/WO2010001080A2/fr active Application Filing

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