Science and Technology for Army Homeland Security Report 1 (2003) / Chapter Skim
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2. Indications and Warning Technologies
2. Indications and Warning Technologies
Pages 41-69
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From page 41... ...
, radioisotopes, chemical agents, and/or biological agents and the identification of related S&T, which is cross-cutting in character. The Army is responsible for defending its own forces at home and abroad and will need to acquire the technology to do so iThe important topic of I and W in cyberspace was not addressed due to the short duration of the study.
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From page 42... ...
sensors used for perimeter defense in this chapter, but it discusses them in other chapters. The remainder of this section briefly summarizes technologies for detecting nuclear weapons and radioisotopes, conventional explosives, chemical agents, and biological agents, along with the relevant cross-cutting technologies.
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DARPA has several ongoing programs in lasers and nitride detectors for the ultraviolet and solar blind regions. In a situation where chemical or biological agents have been released into the atmosphere, this technology may be significant for standoff chemical and biological detection, as biological agents in particular have very specific signatures of absorption or emission in the ultraviolet portion of the spectrum.4 Table 2-1 describes traditional imaging sensors.
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It makes little sense, for example, to present data on the sensitivity of a particular diagnostic methodology without also presenting the trade-off with specificity.5 The NRC study Making the Nation Safer (NRC, 2002) calls for the following system-design approach: Establishment of standards for response time and field stability/durability, for example, for detection of WMD; Use of two-level sensor systems in which a low false-alarm-rate sensor with low specificity triggers a second sensor with a higher false-alarm rate but higher specificity; Use of multiple sensors and reasoning algorithms to obtain lower overall false-alarm probability, to predict contamination spread, and to provide guidance for recovery actions; and Use of networked sensors to provide wide-area protection of high-threat targets.
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Figure 2-1 provides the vapor pressure concentrations for a number of chemical agents. When compared with explosives, the chemical agents shown in Figure 2-1 are high-vapor-pressure substances.
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In clean environments where interfering substances can be kept to a minimum, the detection of trace amounts of chemical agents is more straightforward. Table 2-2 provides examples of means of chemical agent detection.
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This technology could certainly be considered as cross-cutting in much the same sense that quantum dots technology is cross-cutting in its applications. Biological Agents The point detection of biological agents is qualitatively different from that of chemical agents.
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Assuming scattering but no neutron capture between the weapon and the detector, the weapon neutron flux from spontaneous fission will equal the background neutron flux at about 15 m from the weapon.6 If one wishes to detect at a longer distance the spontaneous neutron output from the plutonium weapon, one must deploy detectors capable of detecting excess thermal neutrons at levels below the background flux level. A similar situation exists for gamma radiation from plutonium.
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Conventional explosive detection technologies generally fall into two categories: vapor-phase detection and bulk detection. Figure 2-4 provides some insight into the vapor pressures of the better-known explosives.
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SOURCE: Adapted from NIJ (1999~. Modern explosives manufactured to include higher-vapor-pressure taggants will have longer detection ranges.
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CROSS-CUTTING TECHNOLOGIES It is quite clear that the great majority of technologies for the physical detection of nuclear weapons, radiological weapons, conventional explosives, chemical agents, and biological agents require close proximity to the weapon. Detection of chemical or biological aerosol clouds at a distance is possible.
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For example, quantum dots may be fabricated so that a 2-nanometer particle glows bright green while a larger 5-nanometer particle glows red in the presence of white light. These developments originally had nothing to do with the detection of chemical or biological agents, but the dual-use potential was found through clever chemistry.
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forces or to the general population. This distributed sensors approach offers many important opportunities for investigation by the Army S&T program.
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The interrelationships needed among the sensor networks and for the broader intelligence collection activity are difficult to establish, for technical, cultural, and legal reasons. Nevertheless, the committee envisioned a situation where the relevant sensor networks would be queued as a result of intelligence findings, with the intelligence community tasked to undertake focused collection efforts if the sensor networks picked up unusual activity.
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2001. An Introduction to Biological Agent Detection Equipment for Emergency First Responders, NIJ Guide 101-00, December.
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2002. Department of the Navy Explosive Detection Equipment Program-Explosives.
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