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airport detectors not ready for terrorists

by:Kenwei      2019-08-26
Christopher joyce, aiming to thwart the terrorist attack on commercial airlines, still fails to meet the expectations of scientists.
After several years of testing, none of the detector systems meet the minimum requirements set by the FAA (FAA).
Metal detectors and X-
The National Academy of Sciences says the plane has almost eliminated the hijacking. The institute prepared a secret report last year on the detection of explosives.
But the machines are unable to detect plastic explosives, a weapon that terrorists are currently choosing.
These materials are dense, have high energy, and have lower steam pressure than TNT, which makes it difficult for them to smell chemically.
On 1988, plastic explosives blew up Pan jetover Lockerbie.
The Institute\'s research emphasizes that trade will always exist.
Between the risk of lost bombs and delays and interruptions caused by search and false alarms.
There are very few bombs, but the consequences are huge;
Delay is a matter of daily concern.
Experts are now calling for a combination of manual and mechanical interception bombs.
However, it is clear which machine should be chosen.
On 1985, the FAA began to fund the thermal neutron activation test (TNA)
Many say it will be the next generation of screening devices.
Radioactive sources, TNA employee SA-
252, produce neutrals that are slow or \"hot.
Some nuclei of the object capture neutrons and then, in turn, emit gamma rays.
The energy of gamma rays reveals the composition of the object: for example, nitrogen emits gamma rays at 10 points.
8 megabytes of electronic volts
But there is very little information provided by TNA about the shape of suspicious objects.
Nitrogen is almost always an ingredient in plastic explosives-usually at a high concentration.
However, this material was also found in a variety of other materials: certain plastics, silk and nylon are one of the materials that can cause an alarm, 1988, the FAA has asked for a device that can be used at the airport.
The Eshewing machine detects steam, which the agency hopes to have a system that can detect \"a few pounds\" of an explosion within a time period and has a false alarm rate (False positives)
Scan 10 bags in one minute and \"close\" 1 to 2%.
International company for scientific applications (SAIC)
Santa clara, Calif. , says only the TNA machine it produces can get close to that.
TNA had better catch the Lockerbie bomb, the company said.
Experts believe that the weight of the bomb is less than 300 grams.
Peter Trower, a physicist at Virginia Tech in Blacksburg, questioned this by studying TNA and other scanning techniques.
Trower told a congressional panel in September 1989 that TNA did not work as advertised.
Trower quoted a scientist from the FAA as saying that TNA\'s tested performance was only 80 of these bags (containing 2.
5 pounds of the explosion)
False alarm rate is ten percent \'.
Detection of Lockerbie-
SaysHadi Bozorgmanesh, vice president of SAIC, said the size of the bomb TNA can become more sensitive.
However, according to a congressional expert on scanning technology, at this level of sensitivity, the false positive rate will be many times the acceptable range.
TNA also scored lower in the special presidential commission on aviation and terrorism, which was set up shortly after the Lockerbie bombing.
At May1990, the Commission reported that the FAA chose 2. 5-
The pound serves as a threshold for \"best guess\" to detect bombs, for example, without testing the impact of smaller bombs on the hull of the aircraft.
Committee staff also watched the test of the TNA machine at John f Kennedy Airport in New York City.
During the test, plastic explosives Semtex are sent in different quantities in the suitcase through the TNA machine.
Themachine is the same X-
The light provides information about the shape of the object.
‘The results . .
\"I\'m startleng,\" the committee wrote . \"
When a bag containing the minimum detectable weight of the Semtex required by the FAA passed, the machine blocked it in ten minutes.
At 60 per cent of this weight, there are seven bag escape notices in eight passes.
In this figure, the bomb was not found every time.
TNA machines are currently being tested at Gatwick and San Francisco as well as Dulles airports near Washington, DC.
The two will soon be sent to Germany and Belgium.
The sixth machine at Miami airport is under repair.
The FAA\'s goal in 1989 was to install 150 TNA detectors or equivalent systems at 40 airports in the United States and abroad by the end of 1992.
However, FAA spokesman Fred Farler said that \"the whole thing is up\" because of the recent skepticism about TNA\'s performance \".
The FAA has set new, stricter but undisclosed minimum standards, Farrar said.
New Test of TNA combined with X
Ray and other detectors are in progress.
Even if TNA can be improved, airlines may not accept its financial penalties.
The machines are a 10-ton mini-car that costs nearly $1 million each.
Tim Neil of the airline\'s Air Transport Association said twa spent about $100,000 to build a special building for a TNA at Kennedy Airport.
According to researchers at the University of California-Berkeley Transportation Research Institute, scanning can also complicate the timing of the transfer.
They predict that the United States will need 700 to one unit of police airport handling international baggage.
The cost of equipment and housing is at least $0. 5 billion, and the annual operating cost is at least $92 million.
The consensus among the experts is not to rely on a single technology, but to constantly screen passengers and luggage with an increasingly thin sieve.
It is clear that threats are not allowed to pass;
The rest were subject to stricter scrutiny.
For example, a study by the National Academy of Sciences shows that the first level should be \"low technology \".
This means making sure noluggage flies without the owner.
It also includes a \"risk assessment\" of passengers \".
The next step may include hybrid technologies other than metal detectors and single Technologiesbeam X-rays now used.
These may include multiplebeam X-
Leisha steam sniffing. X-
The airport is testing two ray machines with different energies.
Heimann Systems in Isling, N. J. , built a called hi-
Check the cushion of the suitcase.
A set of detectors receive X-
Rays of organic materials such as explosions, while the other detects heavy inorganic materials such as metals.
Steam sniffing generally starts with high-speed chromatography, sampling the air into the chamber.
Chromatography identifies molecules by steam pressure, atomic weight, and solubility in liquid. Hand-
The hand-held version that looks like a vacuum cleaner is made by doctors in Woburn, Massachusetts, and has been tested in nearly a dozen countries, including Germany and Riel.
The State Department wants to check cars entering the embassy with sniffers.
Or hand.
Hold version or large, walk-
David Fine, a chemist and chief scientist at Thermedics, said that passing the model can also check passengers in seconds.
Finn believes that his sniffer EGIS can also find explosives in the open bag, perhaps x-
In 30 seconds, the light is first identified as suspicious.
Critics say that if explosives are tightly wrapped in something like plastic, the sniffers will be foiled. Fine disagrees.
There is a cloud of steam around when you use explosives.
It\'s all over you and your clothes and it will be outside of the plastic.
These are very sticky molecules.
Another promising tool is a computed tomography or CT scan that has been widely used in medicine. CT scans use X-
Fred Roder, a safety expert at Imatron, Calif. , said light but sliced the image to a resolution in millimeters.
The scan indicates the density and total mass of the object and provides a rough clue of its atomic number and composition of elements.
According to Roder, a CT scan should be able to check the suitcase for plastic explosions within 20 seconds.
Anything suspicious can be scanned further for about two minutes.
Get a 3D image.
We can see the battery, the wires, the detonators and the materials made from them, Roder said.
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