djm@castle.ed.ac.uk (D Murphy) (08/02/90)
From: D Murphy <djm@castle.ed.ac.uk> I suppose this might really go into `sci.antiterrorism' :-) but.. An article in `The Scotsman' newspaper today (01-08-90) says that a device has been developed which is capable of detecting small quantities of explosives, including TNT, nitroglycerine and `semtex'. It consists of a handheld, battery operated `sniffer' which passes air sucked from the object being tested into a gas chromatograph. The standardised conditions inside the chromatograph allows the identification of vapours around the object by the time they are retained in the machine. Different retention times both separate components and can identify them by comparison with known values of a `genuine' sample. Israel is said to have bought a couple of the machines for an estimated 200,000 pounds (ca. US$300,000). This is important in combatting the use of `semtex' plastic explosives which do not show up on conventional x-ray scanners. The article did not say whether the `semtex' standard used to allow identification checked for the presence of RDX (hexogen - the explosive constituent of the military semtex-H which caused the Lockerbie disaster) or the plasticising agent which would presumably allow detection of a wide variety of plasticised explosives. It is more likely, however, that the signatures used in identification are mixtures of different components, and that a `likelyhood' criterion is used by the equipment for giving a warning. Murff... djm%ed.castle@nsfnet-relay.ac.uk
gwh%monsoon.Berkeley.EDU@ucbvax.Berkeley.EDU (George William Herbert) (08/06/90)
From: gwh%monsoon.Berkeley.EDU@ucbvax.Berkeley.EDU (George William Herbert) There are a number of explosives detectors out there now; from the primitive (x-rays, hand inspection; miss all but most crude bombs) through explosives sniffing dogs and portable sniffers (better) to the newer neutron and gamma-ray and MRI type detectors. Universally, they can be defeated. The sniffers are vulnerable to hermetically sealed bombs. This applies to both the portable and the fixed, multi-sample units, and dogs. X-rays and people can be fooled by careful design. The Pan Am 103 / radio bomb was one such device. The gamma-ray and neutron-activation types can both be fooled by careful screening. I've seen videos of a counterterror demo; a fully working D-cell battery was run through a full set of the latest and best detectors, then proceeded to detonate (demonstration test) after exposure to airliner flight cabin pressures. Don't ask how they built that one. Rather annoyingly, all the best measures can only screen out dumb terrorists. == George William Herbert == ******************************************* == JOAT for Hire: Anything, == * Warning: This Person Contains Chemicals * =======Anywhere, My Price======= * Which are Known to Cause Cancer, Birth * == gwh@ocf.berkeley.edu == ******** Defects, and Brain Damage! ******* == ucbvax!ocf!gwh == The OCF Gang: Making Tomorrow's Mistakes Today