Itemiser Contraband Detector, an explosive and drug detector.
Aviation Week & Space Technology.- 1996 .- 145, No. 5 — P. 66.
Itemiser Contraband Detector
Ion Track Intruments (USA) has developed an improved detector of explosives, drugs and other contraband goodsItemiser Contraband Detector. It can search a passenger and their hand luggage within 5 seconds to detect traces of explosives on clothing and the outer surfaces of luggage items. Security personnel can switch the detector to explosive or drug detection modes. This switching is done by simply touching the monitor screen. In explosive detection mode, the detector can detect explosive compounds such as dynamite, RDX, PETN, TNT and ammonium nitrate.
Screening does not require direct contact with explosives. Detection is achieved by analyzing traces of explosives and their components deposited on the outer surfaces of baggage items containing these substances.
The Itemiser detector is one of three systems approved by the FAA Technical Center for screening passengers and their baggage. The other two systems in the group operate using a similar ion capture method. The use of technology similar to computed tomography is also being considered.
The Itemiser detector uses a Ion Track InstrumentsIon Track Mobility Spectrometry (ITMS) technology. It involves sampling explosive vapors using a paper filter with vacuum capture or by wiping particles of these substances from the surfaces of inspected objects. The filter with the sample is transferred to the detector, where the sample is heated by a desorber located in the detector. The heated air passes through a semipermeable elastomer membrane that allows vapors to pass through, but retains dust and dirt. The gas purified in this way enters the ionization chamber, the walls of which are covered with foil made of the nickel-63 isotope, which has low radioactivity and emits beta particles. No radiation comes out of the test chamber. Positively and negatively charged ions are formed in the gas, which then pass through a mesh electrode.
Electrical pulses are fed into the chamber at 20 ms intervals, causing the ionized sample to move toward the collecting electrode (collector). By measuring the ion mobility, Itemiser can determine their size and identify them. By adding a gaseous impurity, it is possible to achieve predictable interaction of ions with an electric field, but contraband substances have their own characteristic signature, by which they are identified.
The Itemiser detector is highly sensitive and can detect explosives weighing 100-300 pg (1 pg = 10E-12 g).
The ion trapping technology was used in the early detector mainly due to the lower temperatures used to process the collected samples. If one person places an explosive in a plastic bag and another places the bag in a suitcase, the second person will be left with traces of the explosive from contact with the bag. Even if a third person places another explosive-containing object in the same suitcase, such as a radio containing the explosive, the suitcase will be left with traces of the explosive. When tested in this scenario, the detector detected the explosive four times out of five times. Either party will be left with traces of the explosive and will be detectable by the Itemiser even days later. Ion Track Instruments explosives and contraband detectors are used by airlines, customs, prisons and the armed forces of many countries around the world.