Explosive threats common

A radiation threat, commonly referred to as a "dirty bomb" or "radiological dispersion device (RDD) , is the use of common explosives to spread radioactive materials over a targeted area. It is not a nuclear blast. The force of the explosion and radioactive contamination will be more localized. While the blast will be immediately obvious, the presence of radiation will not be clearly defined until trained personnel with specialized equipment are on the scene. As with any radiation, you want to try to limit exposure. 

Various Ionization Methods for Trace Explosive Threat Detection by IMS Several articles and books review IMS for trace explosives detection [18, 45, 48]. In particular, a review article, describes many of the product ion formation reactions that create IMS product ions from explosive compounds [45]. The review also contains extensive tables of reduced mobility (Ko) values, which are used to identify ions in IMS, for the most common explosive compounds. 

Differential Mobility-MS for Explosive Threat Detection Differential mobility spectrometry (DMS), also known as FAIMS, is a technique closely related to IMS [191-192]. In this system, the ratio of the electric field strength (E, V/cm) applied to the electrodes to the drift gas number density (N, cm" ) is increased to a level beyond that used in DT-IMS (the most common configuration of IMS systems) so that the mobility of the ion (K) is no longer constant but is dependent on the strength of E/N (Townsend [Td]) [192]. 

Explosive-based terrorism is an eminent threat to a civilized and free society. Accurate and cost-effective explosive sensors are, therefore, essential for combating the terrorist threat. Some of the main performance characteristics for explosive sensors include sensitivity, selectivity, and real-time fast operation. As the vapor pressures of commonly used explosives are extremely small, highly sensitive sensors are essential for detecting trace quantities of explosives. Moreover, the sensors should have high selectivity to have an acceptable rate of false positives. Also, these sensors should have the capability of mass deployment because of the breadth of terrorist threats involving explosives [1], Finally, these sensors should have fast detection and regeneration time for fast operation. Currently available sensors are unable to satisfy these requirements. 

Other common chemicals could be deliberately released into the environment, putting wider populations at risk. This could occur within a facility or perhaps by sabotaging a container en route via train or road. During the Atlanta 1996 Olympics, for example, U.S. federal authorities considered potential threats from improvised chemical devices, including the use of high explosives to puncture a train car loaded with toxic chemicals (U.S. Army Medical Command, 1999). 

Disposed (known areas of disposal, e.g., disposal site) Prior to the Vietnam conflict, disposal of ordnance by burial was a common and acceptable disposal practice. Records of these areas are incomplete. Past disposal areas may not now be recognizable as such. In some cases, disposal areas have been discovered in lands accessible to the general population. As with the unknown discharge areas, the explosive potential represents an acute threat to human health and environment. Means to locate buried ordnance disposal sites are required. 

As mentioned, new types of homemade explosives or alternates to common nitrated explosives have appeared in several terror scenes and pose a threat to public safety (see Frame 12.3). To counteract these threats, instrumentation has to be calibrated, data systems have to be revised, and some modifications in operational parameters may be necessary. Some of the major manufactnrers of explosive detectors have characterized operational conditions for the detection of several alternative explosives withont severe deterioration of performance for the standard explosives. In one example, the temperature of the drift tube was lowered to 169°C, and the desorber was set to 220°C. In addition, the instrument was operated in dual mode (i.e., measurement of the negative and positive mobility spectra almost simultaneously). With these modifications, operational detection limits (ODLs), defined by the authors as the mass of target substance that was required to produce an alarm at a given detection threshold, of 50 to 100 ng were established for TATP, ammonium nitrate, and gunpowder. These detection limits have been improved with the cnrrent generation of explosive detectors, especially for TATP. Under these conditions, the response and detection limit for TNT is degraded by a factor of two, but those for RDX and NG are barely affected the detection limit for PETN was improved. ... 

Nitroaromatic compounds (NACs) are widely used as pesticides, explosives, solvents, and intermediates in chemical syntheses. NACs and their degradation products pose a potential threat to ecological and human health because they are toxic environmental contaminants commonly found in soil and subsurface environments at elevated concentrations. At a site in Texas, for example, soil concentrations of NAC contaminants in excess of 75,000 mg/kg have been reported and have been detected at depths of greater than 30 meters at concentrations above human health exposure limits (1). In general, NACs degrade relatively slowly in the environment (2,3). Recent evidence has shown that certain NACs have a high affinity for certain types of clay minerals, and this may contribute to their recalcitrant behavior (4-11). This chapter will examine the chemical mechanisms that govern NAC-clay interactions from two perspectives. First, we will examine... 

Applications of PTR.-MS to Homeland Security The Detection of Threat Agents 313 Table 8.1 Comparison of the properties of some common solid explosives... 

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