Explosive Detection Sensors. Sensors to detect explosives are
not capable of detecting all explosives. There are simply too many
explosives compounds. Because of this, animals (typically dogs) are used
most commonly for this purpose.
a) Vapor detection. One method of detecting explosives is
by collecting the vapors emitted by the explosive material. The electron
capture detector is the only inanimate means of explosives vapor detection
which is currently available commercially. Most explosives vapors have a
high electron affinity, that is, there is a high probability that thermalized
electrons will attach to explosive vapor molecules. As a result, monitoring
the electron concentration provides identification of molecules with high
b) Bulk detection. Detection of the bulk of an explosive
is preferable to detection of explosives vapors since there is more physical
material to be detected. Unfortunately, there are no commercially available
bulk explosives detectors, although several are under development.
Package Search Systems. Package search sensors are available
to prevent theft of contraband or weapons from entering a facility.
a) X-ray systems. X-ray systems are currently in use by
commercial airlines. An image of the contents of packages is obtained by
pulsed X-ray techniques. X-ray baggage inspection systems are designed for
high throughput search of handbags, briefcases, and luggage. Preferential
package orientation may be needed to optimize the probability of detection.
b) Computerized tomography. Computerized tomography (CT)
is an X-ray technique which provides two-dimensional images of
cross-sectional slices of an object. By combining a number of adjacent
slices, a three-dimensional image can be obtained. The CT technique provides
maximum sensitivity and accuracy for material detection and identification.
Building Located Intrusion Detection Systems. This section
provides a summary of the function and placement of interior intrusion
detection systems (IDS). This includes the types of sensors available and
typically deployed. The reader is referred to the following sources for more
detailed design information:
NAVFAC Design Manual 13.02, Commercial Intrusion Detection
Systems, September 1986.
Manual TM-5-853-4, Security Engineering, Electronic Security
Systems, U.S. Army Corps of Engineers, February 1993.
ESE-SIT-0001, Siting, Criteria for Standardized Electronic
Security Equipment, Air Force, March 1991.