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WMD--Hunting Technology

with DWSP (Distributed Weapons Sensors Platform)
Piggybacking Sensors on Fleet Vehicles
A Method for the Detection of Clandestine Weapons and Materials

Example: Utilizing Very Large MultiSensor Arrays in Mobile
Detection Systems while Hitchhiking on Tractor Trailer Rigs
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WMD Hunting Technology History Glossary Links
pdf Version pdf Version
Factors influencing Detection----------Features that can Improve Detection

"GOOGLE Street View Cars To Be Fitted With Sensors to Map Air Pollution..."

This seems like a Perfect Fit for WMD Hunting Also! __Just Saying...


- Cutting Edge --
The Technology of Passive Nuclear Radiation Detection has come a long way; from the humble Geiger Counter to the, Scintillation Counter, to the powerful Compton Camera, and beyond. That distance is an amazing History of innovation and of cross discipline cooperation. Astronomers looking for a way to better "See" X-Ray and Gamma Ray sources in the Universe have lead the way in Passive Detection. 

If Passive Detection fails, one can move to Active Detection or Radiography, which uses X-Rays or Gamma Rays to induce the target material to absorb and/or reflect said radiations, thus indicating its presence.

Beyond that, there is Neutron Activation Analysis (NAA), whereby Neutrons are used to induce Fission in the sought after Fissile material.

Of course, most Active Detection is very Hazardous to humans, and All Precautions Must Be Taken.

Cosmic Ray Muon Radiography, is a new, experimental, technique that uses neutrons generated by Cosmic Ray Muons to identify the presence of [Fissile] special nuclear material (SNM). This technique is Safe to humans.
 

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-Survey of Nuclear Detectors

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-Compton Camera-

The Technology used by Astronomers to seek out Gamma Ray sources 
in the Cosmos; holds great promise in finding Clandestine Nuclear Sources.
 
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Factors influencing Detection of Nuclear Materials
Detecting clandestine nuclear materials is sometimes not unlike prospecting for Uranium deposits in the western desert. In both cases there are several factors which greatly influence detection: 

1)_ Intensity of the radioactive source. 

2)_ The Distance between the source and detector reduces radiation intensity--in air--according to the Inverse Square Law, i.e., the amount of radiation at a given distance from the source is inversely proportional to the square of that distance, e.g., if the exposure rate at 1 meter equals 100 mR/hr then the exposure rate at 2 meters will be 25 mR/hr. see fig

3)_ Shielding of radiation due to the Mass of intervening objects. The amount and type of shielding material, e.g., to attenuate the radiation by half requires: Lead = 0.49", Steel = 0.87", Concrete = 5.0". 

4)_ Background radiation (background count) is caused by cosmic rays, naturally occurring radiation from the soil, radon, plants, nuclear fallout, etc. Background radiation can easily obscure target materials; it is a matter of Signal to Noise Ratio (SNR). 

5)_ Detector types, and their dimensions. Like a lens gathering light, the larger the detector surface area, the "Faster" the exposure.

6)_ Exposure Time, the longer the detector is exposed to the radiation source, the more events (counts) are registered, the better the sensitivity to weak sources, and the greater the spectral accuracy. If there is relative movement between the two, the measurement accuracy will degrade.

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.Features that can Improve Detection
1)_ Selectivity   2)_ Directivity   3)_ Radiography


1)_ Selectivity (DSP)
Spectral Separation and Identification of radiation sources.  A verity of Detectors respond uniquely to radiation from specific isotopes. Selecting out the undesired components can improve SNR greatly. This uniqueness is manifested by different pulse heights according to the energy (expressed in Electron Volts, eV) of the event. In addition some detectors also respond with varing decay times for different isotopes. 
 
Pulse Height
 Pulse Fall Time
  .

Isotope Spectra derived from Pulse Height Count Histogram
 

Example of Nuclide Spectrum Analyzer Computer Display


2)_ Directivity (Imaging)
Directivity (spatial coherence) is not an inherent trait of most detectors. Normally, to achieve Directivity shielding is usually employed.  Unlike non-ionizing radiation, ionizing radiation—X rays, Gamma Rays, Cosmic Rays, etc.—are not easily reflected or focused by conventional means; however, they can be using "grazing."

   a. Shielding If the detector is surrounded by mass—lead, steel, concrete, dirt, etc.—the amount of radiation reaching the detector is reduced depending on that mass, e.g., reduction to half power would require: Lead = 0.49", Steel = 0.87", Concrete = 5.0". If an opening is left in the shielding, radiation entering that opening will be unattenuated—hence Directivity.

        1. Collimation
Oftentimes it is desirable to see the radiation source in 2 dimensions, X, Y.
By arraying multiple individual detectors, each possessing some degree of Directivity, one can have a ‘pixelated’ image of the incident radiation source.

Scintillation Counters in an Array

   b. Analysis of Scattering The mechanism behind radiation detection is the interaction between the incident radiation (photons) and the atoms of the detection medium, e.g., in the case of the Geiger counter, Argon gas, or Nal (TI) crystal in the Scintillation counter. 

When struck by the radiation photon, the atom first absorbs that energy and then releases it in the form of new photons or particles. This scattering can fall into one or all of three categories: Photoelectric Effect, Compton Effect, or Pair Production. 

In the case of Compton Scattering (Compton Effect), there is a release of a free electron from the struck atom, and the original photon (sans some energy); both diverge at angles from the original path of the incident photon (before the collision).
Therefore: by detecting the paths of these scattered particles, and tracing backwards the direction of the origin of the radiation can be deduced.  see below

Plotting Backwards to the Source
 



3)_ Radiography
There are three basic ways to detect fissile material: 
"Passive" detection of the radiation emitted by its radioactive decay.

"Active" detection involves two modalities: 

    1)_Radiography."X-raying" an object using Gamma Rays to detect dense and absorptive materials typical of Fission weapons. 
     Transmission is the classic medical X-Ray
     Backscatter is a new approach that yields significantly improved resolution by focusing a narrow beam and detecting the intensities of the reflected or backscattered radiation.

    2)_Induced Fission, using Neutron Activation Analysis (NAA) Radiography.

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Radiography 
Using Transmission and/or Backscatter X-ray Technologies

Backscatter and Transmission X-Ray

Missile in container as seen by Radiography only
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Neutron Activation Analysis (NAA)
Neutron Inducing Fission: releasing Gamma Ray Photon and Beta Particle.

Neutron Inducing Fission:
releasing Gamma Ray 
Photon and Beta Particle.
   Induced Fission (Neutron Activation Analysis)
Bombarding an object with high-energy Neutrons and detecting the particles emitted by the resulting Induced Fission

Nuclear warhead using Radiography and NAA

Notes: [2] Focusing of Gamma Rays, etc., is possible using "Grazing." more info 



Inverse Square Law-
The radiation field decreases with distance from the source as a function of the Inverse Square Law, which states that the amount of radiation at a given distance from a source is inversely proportional to the square of that distance. 
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-HPGe Radiation Detector/Spectrometer-
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HPGe Radiation Detector/Spectrometer
(High-Purity Germanium)

Mechanical Cryogenic Cooler
HPGe detector cooled mechanical cooler
20x Resolution Improvement over NaI(T1)
www.ortec-online.com/pdf/detex.pdf-
 
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Neutron Detection
BF-3, He-3 Gas Neutron Detectors
 
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PUMA Neutron Sensitive Glass Fibers Technology

Airborne Detector Array using PUMA Neutron bars
PUMA Neutron Sensitive Glass Fibers Technology -->
Airborne Detector Array

PUMA Neutron Sensitive Glass Fibers Technology
and Bismuth Germanate Oxide (BGO) Scintillation Counter

 

Portable Multi-Sensor Neutron Detector
http://www.nucsafe.com/---.------------
Modern Scintillation Counter, with
improved Signal Processing 
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-Very Large Nuclear Detector Arrays-

Large Airborne Detector Array
Road Side Detector Array
 
.Large Area Scintillation Counter

Large Area (~ 22" X 26" X 1.5") Plastic (Organic) Scintillator surrounded by Photomultiplier tubes
Radiation Detection has come long way. There are new detection technologies, as well as improvements in old technology. Todays detectors not only detect radiation but can identify the different types and amounts of radioactive sources. They can also seperate background radiation, such as cosmic rays, from radiation sources of interest. 
...
- Basics --
Ionizing Radiation Detection is dependent on collisions of Incident Radiation with molecules or atoms of the detector medium. These collisions cause conversion of Incident Radiation (Photon particles) to Free Electrons (in the case of the Geiger Counter) and Light Photons (in the case of the Scintillation Counter).
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-Geiger Counter-
Geiger Counter-
Geiger Mueller Tube-
Incident radiation collides with molecules of Argon gas within GM tube releasing Free Electrons which causes Electron Avalanche, thus generating pulses to be counted. .
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-Scintillation Counter-
Scintillation Counter Operation-
Incident radiation collides with molecules of the Scintillator Material releasing Light Photons which are picked up by the system's Photomultiplier Tube, thus generating pulses of varing Heights and Shape that are counted and analyzed for Spectrial information on the Radiation Source. 

 

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 -Experimental-
Induced Fission Detection by Naturally Occurring Cosmic Ray Products
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-Active Interrogation using Muon induced Fission
 
Cosmic Ray Conversions-
 
Cosmic rays are mostly protons from outer space that have kinetic energies as high as that of an apple falling a few meters in Earth's gravitational field. When a cosmic-ray proton strikes an air molecule—typically at an altitude of about 15 kilometers—the result is a shower of energetic particles and radiation. Because the muons produced move at close to the speed of light, their short lifetimes (2.1 microseconds) are extended by the time dilation effect of special relativity, which allows most of them to reach Earth's surface without decaying. 
 

Cosmic Ray Muon Radiography.

Decision Sciences is a technology company with headquarters in Virginia and an R&D center in California that brings together cutting edge science, hardware and software development, systems integration and manufacturing to improve the safety and security of the global community. 
Based on revolutionary and disruptive technology originally invented by physicists at the Los Alamos National Laboratory, the Multi-Mode Passive Detection System (MMPDS) was then developed with considerable private sector investment and expertise. The MMPDS is a totally passive, safe, effective and automated scanning system for quickly detecting, locating and identifying unshielded to heavily shielded radiological and nuclear threats as well as explosives and contraband. 

For more info visit: www.decisionsciencescorp.com or, info@decisionsciencescorp.com.

 

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Keywords: 
CBR, Nuclear, Uranium, Plutonium, Compton Effect, Compton Imager, WMD, Clandestine Weapon, Gamma Camera, Scintillation Counter, Geiger Counter, Radiological Survey, HPGe, Scintillator, Nal (TI), Pulse Height Spectrum, Isotope, Nuclide, Alpha, Beta, Gamma Ray, Neutron, Photon, Electron, Proton, positron, MeV, Inverse Square Law, Fleet Vehicles, Trucking & Courier Services, Motor Carrier, Tractor Trailer, Semi Trailer, Trailer Truck, Freight Motor Carrier, Rail, Container Car, Container, highway surveilance, homeland security, neutron detector, nuclear materials, Cosmic Ray Muon Radiography.
WMD Hunting Technology History Glossary Links
pdf Version pdf Version
Factors influencing Detection----------Features that can Improve Detection

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MISC NOTES:
In the absence of shielding, "ordinary" nuclear weapons-those containing kilogram quantities of ordinary weapon-grade (6 percent plutonium-240) plutonium or uranium- 238-can be detected by neutron or gamma counters at a distance of tens of meters. Objects such as missile canisters can be radiographed with high-energy x-rays to reveal the presence of the dense fissile core of any type of nuclear warhead, or the radiation shielding that might conceal a warhead. If subjected to neutron irradiation, the fissile core of any type of unshielded warhead can also be detected by the emission of prompt or delayed-fission neutrons at a distance on the order of 10 meters.

    * RTD® (Radioactive Threat Detection) technology can detect both neutrons (nuclear WMD) and gamma rays (dirty bombs) during routine X-ray inspections, allowing additional functionality without impacting throughput or the flow of commerce. Competitive systems cannot provide simultaneous inspection.

    * RTD alerts operators to the presence and approximate location of a radioactive threat through a visual pop-up display and the sounding of an audible alarm.

    * AS&E systems employ multiple technologies simultaneously for the best detection results.

      Z Backscatter images reveal the explosives that would accompany a dirty bomb, while Transmission X-rays would expose dense shielding surrounding a nuclear threat.

For added security, AS&E's Radioactive Threat Detection (RTD) technology is an option on selected AS&E detection systems. RTD technology is capable of detecting both neutrons (characteristic of fissionable materials) and gamma rays (characteristic of dirty bombs) during the X-ray inspection process. Gradient color bars, displayed with the scanned images, show the approximate location of the radioactive object, and on-screen and audible alerts signal the operator that radiation has been detected.

Radiography
The examination of the structure of materials by nondestructive methods, utilizing sealed sources of byproduct materials. Radiations can be used to produce images of an object either by measuring their transmission through or their interaction with the object. Medical x-rays and x-ray baggage inspection are examples of transmission measurements. A neutron baggage inspection system images an object by measuring the spatial distribution of capture gamma rays produced by the reaction of neutrons with nitrogen in the object. Autoradiography describes the process of imaging an object using radiations produced by the radioactive decay of nuclides in the object. The radionuclides can be the result of radionuclide tagging, contamination by some source, or they can be produced by irradiating the object with neutrons or other radiations.
 
 

* RTD® (American Science and Engineering Inc.,  (AS&E), Radioactive Threat Detection)