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Portable Device for Detection of Hidden Objects

#2543


Detection of Hidden Objects by Their Dielectric Properties

Tech Area / Field

  • INS-DET/Detection Devices/Instrumentation
  • PHY-ANU/Atomic and Nuclear Physics/Physics
  • PHY-RAW/Radiofrequency Waves/Physics

Status
3 Approved without Funding

Registration date
18.06.2002

Leading Institute
Khlopin Radium Institute, Russia, St Petersburg

Supporting institutes

  • All-Russian Research Institute of Automatics, Russia, Moscow

Collaborators

  • L3 Communications, USA, VA, Arlington\nOak Ridge National Laboratory / Nuclear Science and Technology Division, USA, TN, Oak Ridge\nWestern Kentucky University / Applied Physics Institute, USA, OH, Bowling Green\nScience Applications International Corporation, USA, VA, McLean\nEADS SODERN, France, Limeil-Brevannes\nKyoto University / Institute of Advanced Energy, Japan, Kyoto\nUS Department of Transportation / Transportation Security Administration, USA, New Jersey\nUniversity of Jyväskylä, Finland, Jyväskylä\nUniversity of Padova / Department of Physics, Italy, Padova

Project summary

Goal of the Project.

The goal of the Project is to develop and build a portable device for detection of hidden explosive, narcotic and other dangerous substances. In the proposed portable device the continuous radiation in microwave range will provide a 3-D image of internal structure of the inspected objects, while the not-intrusive elemental analysis with modified neutron-in – gamma-out technique will allow identifying the found suspicious object by its secondary characteristic gamma-radiation.

The range of applications of a portable multi-purpose device, which would be capable of determining spatial structure, contents, and type of the object without breaking into it within several seconds could be very wide. Some of the possible applications and interested parties are listed below:

1. Fast identification of suspicious objects left unattended in public places – antiterrorist squads.


2. Customs control of smuggled goods (e.g. narcotics hidden in containers, etc.) – Customs and border guards.
3. Security on transport – airports etc.
4. Identification of unknown objects in the disaster areas – emergency services.
5. Monitoring of wastes (including nuclear wastes) – environmental agencies.
Current status of the field.

The most promising method of detecting hidden dangerous substances is the so-called "neutron in - gamma out" ("neutron") technique, when the inspected object is irradiated with fast or thermal neutrons with the subsequent detection of secondary characteristic g-radiation initiated by neutrons in reactions with nuclei inside the object. Spectra of secondary g-radiation can be used to determine elemental structure of the object. As a source of neutrons such device can use either an isotopic source or portable a neutron generator.

The main problem that is hindering the development of this method is the high background of g-radiations resulting in a significant increase of the detection time. In modern devices that use isotopic sources of neutrons (for example, PINS) or neutron generators (for example, PELAN, NIGAS) the typical identification time is from several minutes up to tens of minutes.

One of the possible ways of advancing the “neutron” technique is using detectors of accompanying particles that allow determining time of emission of neutrons from the source. In this case detection of secondary g-radiation is done in narrow (nanosecond) time interval, which results in reduction of the background, and consequently of the detection time.

Systems for non-intrusive analysis based on portable neutron generator with detector for associated alpha-particles (APSTNG method – Special Technology Laboratory, HiEnergy Microdevices, USA) achieve neutron flux correlated with the direction of the associated a-particle of the order of 105 neutrons/second. This flux is too low to be used in real-life applications. Limitation of the flux of correlated neutrons is due to construction of the neutron generator, efficiency of the system for detection of the accompanying a-particles by a scintillator (10% - 40%) and the count rate of the photo-multiplier.


In the framework of the ISTC Project #1050 a mobile device for detection of explosives has been developed, which is based on isotopic neutron source 252Cf (106 neutrons/second) with built-in system for detection of accompanying fission fragments. Using associated particles allowed reducing the background by more than an order of magnitude, thus achieving detection time of several minutes, previously possible only for systems with much stronger neutron sources. Use of isotopic neutron source limits the range of application of the device.

Contribution of the Project to the selected field.

We propose to localize and identify objects by a combination of two methods: 1) a modified method of detection of secondary gamma-rays from the object with subsequent determination of its chemical content, and 2) a method based on detection of reflected electromagnetic waves of the UHF range.

The main innovation concerning the microwave technique consists in use of continuous microwave radiation in a super-wide frequency band allowing distinguishing between objects by their dielectric properties with the spatial resolution about several millimeters. During work on the ISTC Project #1050 dielectric properties of different explosive substances and common non-explosive materials in the frequency range 5 – 26 GHz were directly measured. Dielectric properties allow distinguishing between explosives and household organic substances, which frequently cause false alarms of the x-ray equipment, and obtaining images with spatial resolution about 1 cm.

The main innovation of the neutron-in – gamma-out technique consists in using a neutron source based on portable neutron generator with the built-in segmented system of detection of the alpha-particles, which accompany neutron emission in the t(d,n)a reaction. Detection of g-rays in narrow (nanosecond) time gates relative to the time of detection of the corresponding alpha-particle in a segmented detector allows one to determine elemental structure and position of the hidden substance in the inspected object within about 10 seconds (for hidden objects weighting more than 50 grams), which is about 100 times faster, than in existing analogues.

Technical approach and methodology.

“Neutron” technique. To overcome current limitations of the APSTNG method in the present Project it is proposed to increase the flux of correlated neutrons by two orders of magnitude – up to 107 neutrons/second. This will be achieved by using a specially developed portable sealed neutron generator with built-in sectioned semiconductor detector of accompanying a-particles, that would have improved resistance to radiation damage. Preliminary tests of the semiconductor detector placed close to the target of the NG-400 neutron generator at Radium Institute and inside a prototype of a portable neutron generator manufactured by the All-Russia Institute of Automatics have shown that the detector remained operational at total number of detected alpha-particles from t(d,n)a reaction corresponding to about 5000 hours of work of the portable neutron generator.

The position-sensitive detector of the accompanying a-particles that will be built into the neutron generator would allow obtaining segment-by segment image of the object in the horizontal plane, while using nanosecond time intervals would allow obtaining images of slices in-depth, i.e. obtaining the full 3D elemental image of the object.


“Microwave” technique. Continuous radiation possesses in some cases advantages over pulsed systems (radar). Simultaneous detection of the amplitude and phase of reflected electromagnetic waves in the UHF range using stepped-frequency radar methods allows fast localization (imaging) of the “anomaly” within the inspected area, and assigning it to a certain class of substances by its dielectric properties.

Unlike the “neutron” technique, the method based on detection of reflected electromagnetic waves of the UHF range is not capable of identification of objects that are covered with metal coating, but can signal the presence of such coating in the inspected area, i.e. localize the suspicious object.

Amount of work.

The duration of the Project is 3 years. The following new equipment will be designed and manufactured:

1. detector of secondary g-rays with required energy- and time resolution;


2. prototype of portable neutron generator with built-in system for accompanying particles detection, that would have extended lifetime;
3. functional prototype of a device for localization of anomalies based on detection of reflected EM waves in UHF range;
4. prototype of the specialized electronic block for servicing the neutron source and for obtaining and processing energy and time information from the g-detector with the necessary software.
The manufactured equipment will be tested, the decision-taking procedure will be developed, and the corresponding software will be written.

On the basis of the results of tests, portable device for detection of dangerous substances will be built.

Competence of participants.

V.G.Khlopin Radium Institute, St.-Petersburg, has experience in the following areas related to the Project: building a mobile device for explosives’ and other contraband detection on the basis of isotopic neutron source (ISTC Project #1050); making and using detectors of a-particles, including detectors working in ultra-high vacuum; using microwave radiation for localization of hidden explosive substances.

All-Russia Institute of Automatics, Moscow, is the leading organization in Russia in the production of reliable portable sealed industrial neutron generators that have extended lifetime.

Expected results and their application.

The device created as a result of the Project will be capable of detecting hidden objects weighting over 50 g. within 10 seconds, and obtaining image of the inspected area with resolution about 1 cm. Mass of the device will be not more than 40 kg., power consumption from battery – about 50 W.

The device could be used by antiterrorist squads, Customs and border guards, airport security, environmental agencies, etc. The projected cost of the commercial version – not more than $100,000.

Meeting the ISTC goals.

The project will: ensure tighter cooperation between specialists from different countries; provide alternative occupation and long-time perspectives for scientists who were previously engaged in weapons production; assist in the solution of global problems of combating terrorism and contraband; provide help in the solution of ecological and sanitary tasks.


Role of foreign collaborators.

Project participants will benefit from the experience of foreign colleagues in planning the work, analysis of the experimental results, and in possible joint scientific and commercial use of results.

The following forms of collaboration will be used: exchange of information, independent verification of results, consultation on development of system for accompanying particles and gamma detection, joint use of equipment, information support of the work.


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