WO2012102766A2 - Système de détection et de localisation rapides et à distance de substances explosives - Google Patents

Système de détection et de localisation rapides et à distance de substances explosives Download PDF

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Publication number
WO2012102766A2
WO2012102766A2 PCT/US2011/053461 US2011053461W WO2012102766A2 WO 2012102766 A2 WO2012102766 A2 WO 2012102766A2 US 2011053461 W US2011053461 W US 2011053461W WO 2012102766 A2 WO2012102766 A2 WO 2012102766A2
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source
thermal neutron
pulsed
gamma
neutron
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PCT/US2011/053461
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English (en)
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WO2012102766A8 (fr
WO2012102766A3 (fr
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Pablo Carlos FLORIDO
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Pacifica Sea Fruits, Inc (A Us Company)
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Publication of WO2012102766A2 publication Critical patent/WO2012102766A2/fr
Publication of WO2012102766A8 publication Critical patent/WO2012102766A8/fr
Publication of WO2012102766A3 publication Critical patent/WO2012102766A3/fr

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    • 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

Definitions

  • the invention relates to the detection of explosives, and more specifically to methods and systems of detecting and locating explosives via thermal neutron analysis.
  • An acceptable response to the explosive threat requires a highly sensitive and non intrusive technology to interrogate or scan a given target or zone at high velocity.
  • Explosive materials are well-separated from other benign materials because of the abundance of certain atomic elements in its atomic composition.
  • gamma rays stimulated by neutrons have been used for the qualitative detection and quantitative determination of many elements.
  • Most nuclei emit characteristic gamma rays following the interaction of the neutrons with the nucleus. Because of the high binding neutron energy and the generally allowed transitions to the ground state of the excited nucleus, the emitted gamma rays have high penetrating energy with an energy spectra and yield that depends on the specific nucleus involved in the nuclear reaction, and then are very suitable for the interrogation of materials as a bulk.
  • Neutron capture and inelastic scattering were utilized in a wide variety of techniques to detect explosives and drugs.
  • TAA thermal neutron analysis techniques
  • FNA fast neutron analysis
  • PFNA pulsed fast neutron analysis techniques
  • thermal neutron interrogation technologies have concentrated their efforts on the detection of the gamma rays produced by the neutron capture with 10.83 MeV transition in nitrogen, because bulk nitrogen is a good indicative of the presence of explosive material. This approach has been considered in the Barko patent.
  • Other fast neutron technologies have concentrated on the four cardinal constituents of explosives: hydrogen, carbon, nitrogen, and oxygen, as is considered in the Gozani and Sawla patents.
  • Other equipments use thermal neutrons to measure the isotope concentration and isotope rate in order to identify the explosive content in unexploded munitions that may have been buried or exposed to the elements for years before they are recovered for example, as developed by Caffrey in the U.S. Pat. No 6,791,089 Bl.
  • Cinausero also used a much higher neutron yield - higher energy D-T neutron generator as a pulsed neutron source, and tried to reduce the background by acquiring the signals after the fast neutron pulsed vanished, but the resulting background was reduced only by a fraction of two, as consequence of the relative large life of the thermal neutrons in the moderator used in the source, compared with the time of flight (TOF) of the neutrons between the source and the target.
  • TOF time of flight
  • the thermal neutron "die away time" is very important in the combination of PFNA techniques with GTNA, and it was incorporated by Holslin et al. in the U.S. Pat. No 7,430,479 in the time analysis for elemental identification in a target irradiated with neutrons. Also it is considered in commercial PFNA/GTNA equipments like the equipment described by Vouropoulos et al.
  • composition during the measuring time Another clear disadvantage in present interrogation technologies with thermal neutrons is that the TOF have the information of the distance between the source and the target, but this information is lost, or strongly degraded, by the overlapping with the time-correlated background produced by the die away time of the source.
  • the physics involved in the die away time of the thermal neutron is well known, and for homogeneous moderators and absorbers there are also well know relationship that can be used to estimate the time required for fast neutrons to reach the thermal energy range. Some typical figures will be given in order to understand the challenge of the synchronic background for the signal discrimination.
  • the die away time depends mainly on the size and composition of the moderator.
  • the average time for a 1 to 10 MeV neutron to achieve energies in the order of leV is approximately 2 ⁇ $ ⁇ in water, and similar results could be expected in other hydrogenated moderators like the high dense polyethylene (HDP) usually used in TNA and GTNA equipments.
  • HDP high dense polyethylene
  • the die away time constant (usually called a) takes and asymptotic value of 0 of about (200 Even for small water cubes or high dense polyethylene cubes with a size of 10 cm per side, the a time constant is about (70 ⁇ 8 ⁇ ) _1 .
  • the total duration of the thermal neutron pulse will be around 210 ⁇ 8 ⁇
  • the velocities of neutrons with energies in the range from 0.025 eV to 0.1 eV corresponds to the range of 2200 to 4400 m/s.
  • the neutrons with 0.025 eV arrives when there still neutrons from the source in the detector (the TOF is 180 ⁇ 8 ⁇ ), or if is at 80 cm the neutrons with 0,1 eV arrives when there are also neutrons from the source in the detector (TOF is also 180 ⁇ 8 ⁇ ).
  • the respective TOF of the source spectra needs to be added to the total duration of the thermal neutrons in the source, and then need to be calculated the total duration of the synchronous background in the detector.
  • the grooved and Cd grid moderator concepts have another different property compared with homogenous moderators: the neutrons beam do not follows the 1/r attenuation law. Because these are basically methods that use neutrons mainly when are in a given direction, then the neutrons have the behavior of a beam with a divergence produced by the specific geometry of the groove or the grid spacing and thickness.
  • a great diagnostic advantage in the sensibility and position sensitive response to pulsed thermal neutron sources may be obtained to interrogate a target or scan a zone in search for explosives or other dangerous substances, if other concept of thermal neutron source and gamma detector is used.
  • a suitable low background measurement with all the TOF information can be obtained with thermal neutron analysis techniques, if the thermal interrogation pulsed has a die away time much shorter than the TOF between the neutron source and the target.
  • the present invention provides a highly effective and direct manner to interrogate a target or to scan a zone with short pulsed thermal neutrons beam to measure the gamma response with TOF techniques, with high sensitiveness and velocity by using a new pulsed thermal source, with a thermal neutron die away time much shorter than the TOF of the thermal neutrons from the source to the target position.
  • the present invention provides a rapid and effective system for the reliable detection of explosives using a short pulsed thermal neutron analysis (SPTNA).
  • SPTNA short pulsed thermal neutron analysis
  • the present invention uses a pulsed fast neutron source next to a moderator in the forward direction corresponding to the direction of the beam used to interrogate the explosives, with material and mechanical heterogeneities conceived to obtain a forward collimated thermal neutron beam with high intensity and die away time shorter than the time of flight between the source and the target.
  • the flux of the neutron beam resulting from the forward moderator could be increased with a backward zone designed with material and mechanical heterogeneities to be an efficient reflector without increasing the die away time of the forward moderator.
  • the resulting pulsed neutron beam can be directed to the object under investigation in order to cause thermal capture reactions in a limited small object volume that is defined by the intersection of the thermal neutron beam and the screened object.
  • the signal from the object arrives at the detector and it is discriminated by the electronics in time and energy with a temporal distribution produced by the convolution between the time of the flight of the different neutrons velocity and differential die away time at the different energies.
  • this approach there is as minimal source-correlated background at the detector, a significant amount of net counts coming from the target, well above the uncertainty limit can be achieved in only few neutron pulses.
  • a high velocity explosive detection system can be conceived that triggers an alarm level when there is a simultaneous detection of a given combination of discriminated gamma (or relationship between count rates
  • This equipment can be enhanced also using a temporal distribution figure of merit that corresponds with high probability that the specified explosive constituent elements are present in the object at the same position, and then minimizing the possibility of triggering a false alarm.
  • Another independent feature and advantage of a high velocity explosive detection system is that the electronic processing system could trigger a warning alarm when certain elements are detected in positions that could be used to hide an explosive to the thermal neutrons used by the equipment to interrogate the zone.
  • a high velocity explosive detection system can be designed to scan a zone and to detect a target by the combination of the motion of the source and the detection system with a movable target zone.
  • the object under investigation can be placed in a movable belt, or can fixed to the land and the detection system in a vehicle then producing a relative movement between the object and the interrogation system. If the explosive is large enough to produce a signal during several neutrons pulses, the electronic processing system needs to be able to compensate the higher intensity of the discriminated gamma produce by the larger target, with the different temporal distribution of the convolution of the different time responses.
  • the system can be used to extend the interrogation time, or to reduce the relative velocity movement, by a decision of the operator of the equipment or because was triggered an alarm level.
  • This reduction in velocity can be used to interrogate the target for more characteristics gamma rays that could produce a signal well above over background level or improve the time distribution count rate statistics.
  • more interrogation time can be used for the suspicious target, because the other constituents have low concentration, low cross section or low gamma yield compared with the constituents included in the detection logic of the first alarm level.
  • Another independent feature and advantage of the high velocity explosive detection system is that the high sensitivity of the system with thermal neutrons can be used to design a system to scan persons in a very efficient gamma detection system embedded in a geometry that allows fast transient of the persons with extremely very neutron dose, only triggering few accelerator pulses when the person is at the middle of the detector geometry, walking at normal velocity.
  • This system with proper correction of the source and detectors positioning, die away time and attenuation introduced by the water contained in the human body could be used to detect explosive in small quantities and very low radiation doses, or to trigger a warning message.
  • the particular advantage of this concept is that could be used to detect explosive far away from the neutron source and the detector, and with sufficient large gamma detection panels, could be used to detect at thigh velocity or a vehicle in movement, improvised explosive devices in a distance in the range of several meters to a few tens of meters.
  • the invention is a system and method for fast and effective detection and location of explosive substances, applicable for the detection of explosives in underground mines, general and carry-on luggage, passenger inspection, and improvised explosive devices (IED).
  • the detection apparatus includes a pulsed thermal neutron beam, a gamma ray detection system, data collection modules and detection processing modules.
  • the pulsed thermal neutron beam is produced by fast neutron moderation to thermal energies, with a fast extraction of the thermal neutrons in the direction of the explosives to be interrogated, with a die away time for the thermal neutrons shorter than the time of flight (TOF) between the source and the location of the interrogated substance.
  • TOF time of flight
  • characteristically gamma rays radiate isotropically from the interrogated substance when is irradiated with thermal neutrons. A portion of these gamma rays are detected by the gamma ray detection system, which is placed apart from the short pulsed thermal neutron source.
  • the detectors electronics include a set of different energy discrimination regions of interest (ROI) in pulse which are related with the different energies of the characteristics gamma rays selected for the elemental constituents.
  • ROI energy discrimination regions of interest
  • the detailed shape of the temporal distribution obtained in the different ROI' s is produced by the convolution between the velocity and time distribution of the thermal neutrons beam with the TOF due to the distance between the moderator and the position of interrogated elements.
  • the detection processing modules determines if the different candidates of nuclear reactions coincide in space and quantity to trigger an alarm level and/or define the size and position of the explosive.
  • a small gamma ray detection system could be used for underground mines detection and humanitarian demining.
  • a very high efficient gamma ray system could be used for fast detection of explosives in luggage and to inspect passengers by virtue of the use of few pulsed thermal neutrons with correspondent low dose- conversion coefficient and proper source triggering when the passenger and luggage is in proper position.
  • a fast and long distance IED interrogation system is produced by combining large gamma ray panels with intrinsic narrow beam characteristics of short thermal pulsed moderators and special focusing elements.
  • FIG. 1 is a schematic representation of the pulsed fast neutron source injecting the neutrons in the forward moderator to produce a short pulsed thermal neutron beam (SPTNB).
  • SPTNB pulsed thermal neutron beam
  • FIG. 2 is a schematic representation that shows a schematic Cd grid with moderator between the Cd strips, used as a forward moderator for a fast pulsed fast neutron source to produce a SPTNB.
  • FIG. 3 is a schematic representation that shows a grooved moderator used as a forward moderator for a fast pulsed fast neutron source to produce a SPTNB.
  • FIG. 4 is a schematic representation that shows a given combination of a schematic Cd grid with a grooved moderator used as a forward moderator for a fast pulse fast neutron source, to produce a SPTNB.
  • FIG. 5 shows a schematic representation of a given forward moderator combined with the backward reflector in order to increase the flux in the neutron beam without increasing the neutron die away time.
  • FIG. 6 shows a schematic representation of a forward moderator combined with the backward reflector with a shielding for fast and thermal neutrons that are not in the direction of the neutron beam.
  • FIG. 7 shows a schematic representation of an apparatus for detecting explosives substances positioned in front of the neutron beam, and detected with gamma ray detection panels close to the short pulse thermal neutron source, in accordance with this disclosure.
  • FIG. 8 shows a schematic representation of an apparatus for detecting explosives substances by interrogating objects located in a moving belt, with increased gamma efficiency but putting more combination of gamma detectors.
  • FIG. 9 shows a schematic representation of an apparatus for detecting underground explosives substances and/or mines for military or humanitarian demining.
  • FIG. 10 shows a schematic upper view of a moving apparatus for detecting explosives substances hidden in a person while the person is walking, with very high total gamma efficiency when the person is in the middle of the high efficiency and irradiation detection system.
  • FIG. 11 shows a schematic representation of an apparatus for detecting remote explosives substances with an additional focusing device and large panels of gamma detectors.
  • FIG. 1 illustrates graphically an apparatus with a moderator to produced pulsed thermal neutron beam with the a temporal behavior of a short die away time compared with the die away time of a similar pure homogenous moderator with the same size, for detecting explosives and other substances (not shown) in a target (not shown) by detecting the gamma rays (not shown) with gamma detectors (not shown) in accordance with the present invention.
  • the apparatus has three main components, a pulsed fast neutron source 50, a heterogeneous moderator 60 located in the forward direction, defining the forward direction 70 as the direction in which the system is designed to produce the thermal neutron beam 80 to interrogate the target (not shown).
  • the duration of the neutron pulse of the pulsed fast neutron sources need to be shorter than the moderator thermal neutrons die away time, or the time of flight of the main fraction of the thermal neutrons to arrive to the position of the explosive (not shown) to be detected.
  • the heterogeneities in the heterogeneous moderators 60 are spatial distribution of the moderator substance (usually a solid or liquid highly hydrogenated material compound by hydrogen with heavier atoms with low thermal neutron capture cross section), combined or not with different zones of thermal neutron absorbers, conceived to have short die away time for thermal neutrons compared with the die away time for thermal neutrons for the same pure moderator substance with the same external dimension.
  • heterogeneous forward moderator 60 to detect explosives (not shown) located in the trajectory of the thermal neutron beam 80 is established when the short die away time is also smaller than the time of flight of the main fraction of the thermal neutrons to arrive to the position of the explosives (not shown) to be detected.
  • FIG. 2 illustrates one of the more simple techniques to produce this type of heterogeneous moderator utilizing thin thermal neutron absorber strips 100 in a square arrange, with a face without thermal neutron absorber sheet perpendicular to the forward direction of the thermal neutron beam, with highly hydrogenated solid or liquid moderator filling the space between the absorber strips, and a thermal neutron absorber sheet cover in the opposite face of thermal neutron beam face to absorb the thermal neutrons that are reflected from the surrounding media to the moderator.
  • SPTNBS short pulsed thermal neutron beam source
  • FIG. 3 illustrates another simple technique to produce this type of short pulsed thermal neutron beam for explosive detectors utilizing a simple highly hydrogenated solid moderator 110 with mechanical grooves 120 in the face perpendicular to the forward direction of the thermal neutron beam 80, with a neutron absorber covering all the other 5 faces of the heterogeneous moderator.
  • a similar grooved moderator concept could be build with a highly hydrogenated liquid moderator if the grooved shape is produced by a solid made with a material with high atomic number and low thermal neutron capture cross section.
  • FIG. 4 illustrates another more complex technique to produce this type of short pulsed thermal neutron beam utilizing a combination of thin thermal neutron absorber strips 150 boxes surrounding with each box a small grooved 160 highly
  • FIG. 5 illustrate an improvement of the apparatus of FIG 1, adding a backward reflector 200 to those fast neutrons produced by the pulsed fast neutron source 50 of FIG. 1.
  • This reflector is not in the solid angle of the forward short pulsed thermal neutron beam moderator 60.
  • This backward moderator in conceived to increase the income flux of those neutrons with higher energy than the thermal neutrons to the forward short pulse thermal neutron beam moderator but without increasing at the same time the thermal neutron die away time in the neutron beam without reflector. This can be achieved by using a homogeneous mixture of a highly hydrogenated reflector and an thermal neutron absorber, or with a proper spatial distribution of the highly hydrogenated reflector substances combined or not with different zones of neutron absorbers.
  • this backward reflector could be similar to the forward moderator alternatives of FIG. 2, FIG.3 and FIG. 4, but using grid spacing or grooved characteristics to ensure a die away of the thermal neutrons shorter than the one of the forward moderator, orienting the reflecting neutrons face in the same direction of the neutron beam.
  • FIG. 6 shows an improvement of the apparatus of FIG. 2 adding a fast and thermal neutron shielding 210 to reduce the income flux to the backward reflector and a forward moderator 60 to reduce the time dependant background in the gamma detectors (not shown) and also to reduce the neutron dose to the operator and public.
  • This thermal neutron shielding is a combination of a highly hydrogenated moderator with size and concentration of a neutron absorber, high enough to ensure that its die away time is shorter than the SPTNBS die away time.
  • FIG. 7 illustrates a schematic view of a complete explosive detection equipment designed using the SPTNBS of FIG. 6.
  • the interrogated object 300 intercepts the thermal neutron beam 80 then producing characteristics gamma rays 310 which are radiated isotropically and detected with an array of gamma detectors 320 adjacent to the neutron beam 80.
  • Each detector has their own pulse-height detector and time electronics 330, surrounded with shielding 340 for fast and thermal neutron and gamma rays.
  • the output of the electronics of the detectors is then analyzed by the detection processing modules 350 to elaborate the energy and time information in order to produce the information about the composition and location of the interrogated object.
  • pulsed fast neutron source 50 have the capabilities to generate fast neutrons pulses having a neutron yield of up to 3 x 10 10 neutrons per second at present, with a neutron energy of 14 MeV per neutron using D-T fusion reactions.
  • pulsed neutron generators are in the form of a tube of about 2 to 5 cm in diameter and 1 meter long.
  • One particular type of highly hydrogenated material for the heterogeneous moderator 60 is a high dense polyethylene or water, if proper casing is assured.
  • a particular type of thin metal thermal neutron absorber neutron strips 100 and 150 sheets are made by Cd thin metal sheets, which have a very high neutron absorber cross section for neutrons with less than 0,7 eV. If the Cd sheet are about 1mm of thickness, the sheet is consider as black for neutrons with less than 0,7 eV.
  • This energy limit has been taken as the upper limit of the thermal neutrons for simplicity, but this is only for a general description point of view because this limit is more corrected called the Cd cut off limit (according with Beckurtz et al.) because there is a small fraction of neutrons in the range between the 0,7 eV and 1 eV that still have upper scattering then correspond to the thermal neutron scattering zone.
  • this difference is not relevant because in this energy range the proposed short pulsed thermal neutron beam die away time is very small and the time of flight is also very small, then it does not have a relevant effect on the signal to background ratio in the gamma detectors 320.
  • gamma detector 320 panels could be build by using arrays of large Nal(Tl) scintillations crystals, in the range between 3 x 3 x 3 to 5 x 5 x 10 inches. These scintillators have a very large detector and photo-peak efficiencies at high energy as could be expected to be used for the interrogation of Nitrogen, which produced gammas rays 340 with 10,83 MeV with relative high yield.
  • the electronics 330 for pulse high discrimination and timing discriminate the energy and timing separately for each detector to reduce the effect of pulse high analysis distortion by pile up, and to reduce the dead time in the electronics. But if a particular embodiment does not have the problems related with high count rate (pile up, dead time), the detectors can be grouped in a few or even a single one electronic box for pulse-height discrimination and timing.
  • the detection processing modules 350 can be a simple alarm level if the signal produced by the detector corresponds to a suspicious count rate in the selected energy ROI with a suspicious time distribution, or could have an algorithm to invert the time of flight convolution produced by the target distance and size with the die away time at the thermal neutron source in order to calculate the spatial distribution of the interrogated nucleus. Then the technique can be used to look for the spatial and energy distributions of atomic elements matching the explosive composition.
  • FIG. 8 illustrates an schematic representation of an apparatus for the detection of explosive substances 500 hidden in a close box or luggage 510 and being interrogated with a SPTNBS 520 apparatus, with several arrays of gamma rays detectors 530 located around the irradiation position in order to increase the gamma ray detection efficiency to have fast velocity to detect small quantities of explosives.
  • the different position of the gamma ray detectors do not influence the time of flight because the only relevant time of flight corresponds to the neutron source to target distance, because average thermal neutrons flight at 2200 m/s, and gamma rays flight at 3 x 10 m/s.
  • the high number of detectors will increase the equipment sensibility to have a higher detection velocity, with the belt running continuously at least at 0.5 m/s.
  • This embodiment could be used to extend the interrogation time by stopping or reducing the velocity of the moving belt based on the decision of the operator of the equipment or because an alarm level was triggered. With lower velocity, it would be ease to interrogate the target for more characteristics gamma rays or improved the statistics of the time distribution count rate, and to give more information to the operator.
  • the system could also trigger an alarm if a large hydrogenated volume has been put inside the inspected box or luggage, because is very easy to detect large hydrogen volume with the gamma detector 530.
  • a second neutron short pulsed thermal neutron beam 520 apparatus can be placed in the opposite side of the inspection volume in order to reduce the effect of the neutrons moderation.
  • FIG. 9 illustrates a schematic representation of an apparatus for the detection underground explosives substances and/or mines for military and humanitarian demining.
  • a combination between a SPTNBS 520 apparatus and detector 530 is placed in a platform in front of the moving vehicle 610 to prevent the detonation of the vehicle if an explosive substance 620 is below the vehicle.
  • the beam 80 can scan for explosives 620 continuously in the zone between 10 to 20 cm below the earth level at a velocity of at least 1 to 2 m/s.
  • the interrogation time can also be extended by stopping or reducing the velocity of the vehicle based on a decision of the operator or because an alarm level was triggered.
  • FIG. 10 illustrates a schematic representation of an apparatus for detection of explosives substances hidden in a person 700 while the person is walking; with very high total gamma efficiency produced by the combination of moving gamma detection panels 710 and fixed gamma detection panels 720.
  • the apparatus triggers just a few neutron pulses from the SPTNBS 520 to interrogate the person.
  • the embodiment was shown as a rotary panel and this geometry could be used to scan a continuous walking person stream if in the different rotary panels 730 gamma detectors are placed looking for a gamma signal in both faces of each rotary panels.
  • a different equipment for the same objective could be built with less gamma ray detectors if the system is built with a sequence of two sliding door open and closing continuously, triggering just a few neutron pulses during the small instant in which the two doors are closed. This type of equipment is possible because the dose quality factor for thermal neutrons is just a small fraction of that corresponding to the fast neutrons and because the sensibility of the detection has been strongly increased by the reduction of the time correlated background.
  • FIG. 11 illustrates a schematic representation of an apparatus for the interrogation and detection of remotely hidden explosive substances 800 corresponding to an improvised explosive device (IED).
  • the apparatus is designed using a SPTNBS 520 combined with an additional thermal neutron beam focusing element 810.
  • An example of the thermal neutron beam focusing element can be built with a structure of sheets of small angle scattering materials like Ni.
  • the gamma response is measured by the gamma array detection panel 530.
  • the scheme shows a very small gamma detection panel for illustrative purposes, but a large panel, in the range of 1 to a few square meters of area could be needed depending on the desired detection distance 820 between the explosive 800 and the SPTNBS 520, the efficiency of the short pulsed thermal neutron moderator 60, the divergence angle of the beam 80 and the neutron yield of the fast pulsed neutron source 50.

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  • Life Sciences & Earth Sciences (AREA)
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  • Analysing Materials By The Use Of Radiation (AREA)

Abstract

L'invention concerne un système et un procédé de détection et de localisation rapides et efficaces de substances explosives. L'appareil de détection comprend un faisceau pulsé de neutrons thermiques et un système de détection de rayons gamma. Le faisceau pulsé de neutrons thermiques est produit en modérant des neutrons à des énergies thermiques en un temps réduit, avec une extraction rapide des neutrons thermiques dans la direction de la substance à interroger, avec un temps d'extinction des neutrons thermiques plus court que le temps de vol entre la source et la substance interrogée. Des rayons gamma rayonnés de façon isotrope sont détectés par le système de détection de rayons gamma, qui est placé à l'écart de la source de neutrons. La distribution temporelle du taux de comptage obtenu dans les différentes régions d'intérêt (ROI) discriminées par l'énergie se produit lorsqu'il n'existe aucun effet pratique de l'arrière-plan synchrone du fait de l'interaction directe entre la source de neutrons et le système de détection de rayons gamma.
PCT/US2011/053461 2010-09-30 2011-10-20 Système de détection et de localisation rapides et à distance de substances explosives WO2012102766A2 (fr)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6410157A (en) * 1987-07-03 1989-01-13 Nippon Atomic Ind Group Co Detection of position of fissionable material
US5528030A (en) * 1995-03-17 1996-06-18 Western Atlas International, Inc. System for determining gas saturation of a formation and a wellbore through casing
US20070102646A1 (en) * 2003-12-16 2007-05-10 Mark Goldberg Method and system for detecting substances, such as special nuclear materials
US20080017806A1 (en) * 2006-07-18 2008-01-24 Norris Wayne B Remote detection of explosive substances
US20080191140A1 (en) * 2007-02-09 2008-08-14 Mcdevitt Daniel Bruno Dual modality detection system of nuclear materials concealed in containers

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6410157A (en) * 1987-07-03 1989-01-13 Nippon Atomic Ind Group Co Detection of position of fissionable material
US5528030A (en) * 1995-03-17 1996-06-18 Western Atlas International, Inc. System for determining gas saturation of a formation and a wellbore through casing
US20070102646A1 (en) * 2003-12-16 2007-05-10 Mark Goldberg Method and system for detecting substances, such as special nuclear materials
US20080017806A1 (en) * 2006-07-18 2008-01-24 Norris Wayne B Remote detection of explosive substances
US20080191140A1 (en) * 2007-02-09 2008-08-14 Mcdevitt Daniel Bruno Dual modality detection system of nuclear materials concealed in containers

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WO2012102766A3 (fr) 2013-10-10

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