To detect prohibited substances, such as explosives and drugs, there are three basic pieces of equipment: a metal detector, an X-ray and a trace detector, which indicates traces of explosives and drugs on the passengers’ bodies and clothes. “In Europe and the United States, the focus of this device is on detecting explosives, but here they are mainly useful in combating international drug trafficking,” explains security equipment specialist Luiz Góes, from Ebco Systems.
Tight marking at airports is a phenomenon that began in the 1970s, when terrorists began hijacking planes, and intensified in 2001, after the terrorist attacks in New York. Understand how the technological “sniffers” in the boarding section work.
Vision beyond reach
The combination of three devices does not allow anything to go unnoticed
Metal detector
– (Gabriel Silveira/)
invisible field
On each side of the portal is a coil of copper wire.
– (Gabriel Silveira/)
In figure 1, it is connected to the electric current, which turns on and off 60 times per second. Each time it turns on, an electromagnetic pulse is formed, which induces the formation of another pulse on side 2 of the portal.
The electromagnetic field induced in the coil on side 2 generates an electric current in the copper wires. When someone crosses the portal carrying a metallic object, it interferes with the electromagnetic field and, consequently, with the current on side 2. The copper wires present there are connected to sound equipment, supplied by electric current, which pulses 60 times per second.
If the current changes in one of the pulses (due to the presence of metal), the device senses the change and beeps.
X-ray
– (Gabriel Silveira/)
X-rays are particles with a high degree of energy, capable of passing through any organic material and various mixed materials (part organic, part inorganic). The airport device emits two beams of X-rays, thin enough to “slice” objects at an angle to allow overlapping objects to be read.
The intensity with which X-rays pass through each object depends on the material it is made of. Organic materials let virtually all radiation through, while metallic materials block most of it. This radiation is measured by two layers of receivers (1 and 2, in the drawing below).
After passing through the objects, the radiations of different intensities reach the receivers of the first layer. Weak radiation (blocked by an object) is captured by it, but it does not go beyond the copper filter that separates layers 1 and 2. Already strong radiation crosses the copper filter and reaches the receivers of the second layer.
– (Gabriel Silveira/)
The computer interprets the data received by receivers 1 and 2. If the radiation has not reached layer 1, it means that there is metal in the suitcase. If you made it to layer 1 but not layer 2, you have mixed material. If it made it to layer 2, it’s organic. The computer paints the objects with different colors, according to the material.
trace detector
– (Gabriel Silveira/)
Everything we touch leaves microparticles trapped in our bodies. Molecules of these filth are always flying around us. When the passenger passes through the trace detector, it blows a wind that pushes part of these molecules towards a collector.
The collector blocks the larger particles, taking only a few molecules into the ionization chamber, where they receive a positive electrical charge and stick to a negatively charged electrode. Then, the chamber reverses the charge of the electrode and the molecules run towards another electrode installed in the same chamber.
– (Gabriel Silveira/)
As each molecule has a different weight, each one completes the race between one electrode and another in a different time: the light ones arrive faster. As the device already has the running time of the prohibited substances in its memory, it beeps when the time of a molecule matches the blacklist.
Puppy
Despite all the technological apparatus, the 240 million olfactory cells (20 times more than ours) of a scent dog are not overlooked in the security system. Trained from birth to find drugs, they search checked baggage and, at some airports, checked baggage as well.