Metal detectors, in other words, the frames that we see at airports, train stations and in the subway, are able to catch any dangerous metal-containing substances and objects. But all the same, the human factor remains the main one - only competent specialists will be able to identify the criminal in a large stream. The experts spoke about the principles of operation of metal detectors and the tasks of public security officers.
On the afternoon of April 3, a suicide bomber detonated a homemade bomb in the St. Petersburg metro. 14 people died, more than 50 were injured. According to preliminary data, a moving car was blown up by a native of Kyrgyzstan, he also planted another bomb on the “Rebellion Square”, which they managed to deactivate.
After the terrorist attack on transport throughout the country, security measures have been strengthened. Somewhere this led to queues during peak hours, when the throughput of one or two arched metal detectors was not enough. At the same time, social networks were filled with dissatisfied and bewildered comments that “everyone squeaks anyway”, “if necessary, it will blow through” and so on. In particular, such reviews are written by residents of the capitals, Novosibirsk and a number of other cities where there is a metro.
Catches metal
At most public transport facilities and in the buildings of large institutions, there are two types of metal detectors: frame (arched), through which the flow of people passes, and manual for personal searches. The principle of operation of arched and hand-held detectors is identical. They differ only in the level of sensitivity. And, for example, if the result of passing through the frame is doubtful, the security representative can additionally scan with a hand-held device.
The use of such metal detectors is regulated, in particular, by the Law on Transport Security.
“During inspection, additional inspection and re-examination, in order to ensure transport security, X-ray television, radioscopic installations, stationary, portable and hand-held metal detectors, gas analytical and chemical equipment, as well as other devices that ensure the detection of weapons, explosives or other devices, objects and substances in respect of which a ban or restriction on movement to the transport security zone has been established,” the law says.
FACT: Scientists from a number of countries do not abandon the idea of educating sappers from rats. First, rodents are taught to identify explosives by smell (giving a treat for each detection), and then transferred to field training. Rats attached to a special light grate (mines do not work for small weights) are rolled through the minefield. Sensing a mine, the animals begin to squeak, scratch, and break out. Here the sapper comes into play, who neutralizes the find. So far, this technique has not been widely adopted. Despite the advantages, there are also disadvantages - the rat is able to examine very small areas of the territory per day.As reported on the website of the Novosibirsk metro, at all stations, the rules for selective screening of passengers using certified general-purpose stationary metal detectors "Rubicon" and manual selector microprocessor metal detectors "Oberton" are defined.
The frame "Rubicon", as they say on the manufacturer's website, is designed to detect metal objects, namely weapons hidden under a person's clothes.
“The principle of operation of a stationary multi-zone metal detector is based on a change in the spatial distribution of a low-frequency electromagnetic field when metal objects are introduced into the field. The electromagnetic field is created using two coils located in the side walls of the frame,” the device is described.
The frame has high noise immunity, that is, it is not affected by smartphones and other electronic devices. And setting the operating modes and parameters of the detector is carried out using the built-in control panel, access to which is closed to outsiders.
The device has two main modes of operation: continuous - for inspection of the mass flow, and discrete - infrared sensors of the passage put the detector into an active state and analysis is carried out only when passing through the frame. POV: We survived the suicide car
When the device detects a metal object, it beeps and uses light indicators to indicate in which part of the frame the detected object is located. In total, the Rubicon has about 100 sensitivity levels and is capable of passing about 50 people per minute. But there are frames with other parameters.
As Tatyana Levchenko, head of the STB security agency, said, frame metal detectors initially have different levels of sensitivity, or they can be adjusted to a different amount of metal that will be captured. Today, large institutions prefer to set the highest sensitivity - to the minimum volumes.
Regarding the frequent reproaches of visitors that the frame “beeps for everything, it only delays” or “does not work”, the interlocutor explained that there are models of devices without sound signals: “Often metal detectors report not with sound, but with a vibration signal so that a person does not know that he worked." Also with handheld detectors.
The hand-held selective microprocessor-based metal detector "Oberton", which is often used at transport facilities, is equipped with an audio-visual detection indication that differs in tone and color for ferrous and non-ferrous metals. It also has the ability to install a vibration alarm to ensure the secrecy of the indication or to work in places with high noise conditions.
"Overtone", depending on the set sensitivity level, can detect ferrous metal objects, such as a Makarov pistol at a distance of 22-30 centimeters, an RGD grenade - 13-26 centimeters, a knife - 10-20 centimeters. From non-ferrous metal, he can detect, for example, a bullet with a caliber of 7.62 mm at a distance of 5-8 centimeters, a gold ring - 3-5 centimeters.
Baggage inspection is carried out differently - with the help of an X-ray scanner. The main part of such scanners is an X-ray generator, a data processing unit for converting the signals received from the detector line into an image, and a conveyor that is used to carry luggage through the scanner.
The resulting images are displayed on a computer terminal, usually located near the scanner. Then everything depends on the operator, who evaluates what he sees on the screen.
The main thing is people
“They (detectors) respond perfectly to metal. Another thing is that each metal detector must be controlled by a person who, upon receiving a signal, somehow reacts: he inspects additionally ... or not, ”commented a former employee of the state security organs (FSB), reserve colonel, an expert in the field of private security activities Vladimir Chernikov .
According to the interlocutor, the frames often work, but, of course, not everyone is inspected. “Employees pay attention to a person's appearance, behavior, and other factors. For example, someone who is carrying something has eyes running around, and this immediately arouses suspicion. Equipment does not work without people, and people are such a subtlety, everything is very subjective, it depends on skill and professionalism,” Chernikov said.
According to the expert, today the most advanced inspection equipment is in Israel, and the situation there is not significantly improving. Of course, the equipment will change. But professional criminals also change, they act outside the box and find new ways to get around technology.
“There is another reliable method. I served in the state security agencies, these things were decided through agents. These are people who permeate the entire society and tap, prompt, and you can turn on in time. If such counterintelligence work is not carried out, then the technical means and the people who are with them are not very effective. It is impossible to watch a lot of people, and unprofessional crooks are scared away. Professionals can only be reached with the help of agents. Here the role of the FSB is very significant, this is their main business,” the expert noted.
FACT: The sense of smell in bees and wasps is better than in dogs. That is why the DARPA specialist (USA) and a number of others decided to train them as sappers. It turned out to be easy to teach insects to detect explosives - dinitrotoluene (one of the main components of explosives) was mixed with sweetened water, and gradually the bees began to associate this component with delicacy. The bee detector really works in some places - bees placed in special devices, if they smell explosives, are immediately activated.
What happens if a person with a pacemaker goes through a metal detector, and is it true that we are irradiated when checking at the airport? Read about how the framework works in the material of the Moscow 24 portal.
A bit of history
The first metal detector was invented in the USA in the 20th century. Initially, the device was developed to prevent theft of metal parts from factories.
Scottish physicist and inventor of one of the first telephones, Alexander Graham Bell, used a metal detector to detect bullets in the chest of US President James Garfield in 1881. However, this attempt failed because the president's body was on a metal bed, and this misled the metal detector.
The use of detectors in the field of security began thanks to Garrett Metal Detectors, which, on the eve of the 1984 Olympic Games, first introduced frame and hand-held metal detectors.
How metal detectors work
Photo: Portal Moscow 24/Alexander Avilov
Metal detectors are designed to identify and classify the presence of metal in a person's pocket or luggage. Among the detectors, there are: ground, military, underwater, deep, inspection (arch or frame) and a magnetometer.
Metal detectors are very sensitive and can react not only to metal
Stanislav Vinogradov
According to Stanislav Vinogradov, lecturer at the Department of General Physics at the Moscow Institute of Physics and Technology, the metal detector senses changes in the alternating electromagnetic field that the metal inside the frame introduces.
“Depending on the design, it (the metal detector. - Portal Moscow 24) “responds” either to a change in the frequency to which it is tuned, or to the appearance of an electromagnetic signal reflected from the metal, or to a change in the amplitude of current oscillations in the frame,” the expert explained.
In general, the device is very sensitive: it can react not only to metal, but even just to the human body, which is a current conductor, Vinogradov added.
As the physicist noted, the sensitivity is tuned to a certain amount of metal. Some metal detectors can also respond to the type of metal, but these are developments of recent years that are not yet widely used.
Are airport detectors harmful?
Photo: Portal Moscow 24/Lidia Shironina
Surely, many have noticed that in front of the frames, for example, in the subway there is an announcement that people with pacemakers may not pass through the detectors. A physics teacher at the Moscow Institute of Physics and Technology explained in an interview with the Moscow 24 portal that there are metal parts in pacemakers, so the metal detector reacts to them in the same way as a watch and change in your pocket. However, when passing the frame, the settings on the medical device may be lost.
In general, the EKS (pacemaker) is sensitive to all electromagnetic and magnetic fields. There have been cases when a person even reacted to fridge magnets or those used to close tablet covers.
When a magnetic field is applied to the device, a person feels a tingling sensation in the fingers when touching the magnets.
Only luggage is irradiated
Stanislav Vinogradov
Lecturer, Department of General Physics, Moscow Institute of Physics and Technology
As for exposure at airports, Stanislav Vinogradov is sure that no harm to humans occurs.
“Irradiation detectors are mainly used to check luggage. But their work, unlike metal detectors, is based on a different principle: X-rays are transmitted, similar to what is usually done in an X-ray room. Such devices “see” density fluctuations under clothing: if the object is dense , then it does not transmit X-rays well and will be seen dark on the screen," the expert explained.
A few years ago, ordinary paper cribs were worn for exams. Russians can only remember the use of special equipment from Leonid Gaidai's well-known comedy "Operation Y and Shurik's Other Adventures", where a student hid the equipment in a compress for an allegedly sore ear. But it turned out that "the professor is not a burdock" and the inventive student was sent for a retake.
Today, everything is different - modern devices have replaced traditional paper cheat sheets. Cell phones and tablets, into which answers to tickets are downloaded, will no longer surprise anyone, but earpieces are something new. On one of the Amur sites there is an announcement that they are rented out for passing the exam, institute exams. The kit includes: an induction headset (antenna), a magnet extractor, 3 micromagnets for a speaker (earpiece), instructions for use. The rental price for this pleasure is 500 rubles per day. We contacted this entrepreneur and found out that when renting micro-earphones, he is personally present, somewhere nearby, within the walls of an educational institution, and there is no need to leave anything as a deposit.
The wireless earpiece measures only 3x2 mm. You put it in your ear, connect the headset to the phone - and go ahead for the desired mark in the student's record book! The complete set is ready to use. By the way, due to their size, the micro-earphones are not noticeable to others even if you look into the ear, where this wonderful cheat sheet is located.
As we were assured in the press service of the Federal Security Service for the Amur Region, these headphones do not belong to special technical equipment or “agency” means, but, of course, it is not good to use them in exams.
To pass the exam, schoolchildren can carry a minimum of items with them, - says Svetlana ABBAKUMOVA, head of the education department of the Blagoveshchensk administration. - They leave all mobile phones, tablets outside the class in which they take the exam. The use of such technical means on the exam is simply not necessary. First, questions cannot be predicted. Secondly, in the future, students who rely on cheat sheets and do not learn the material will find it much more difficult to study in secondary or higher educational institutions. Thirdly, from this year, the introduction of such items will be checked by metal detectors in police regions. Last academic year, there was a case when a student brought a mobile phone to the exam. For this, he was removed from the exam.
Going to an exam with cheat sheets is a common thing, - said the Annunciation psychotherapist Maxim CHEKMAREV. - Students are resourceful, and it pleases. There was a so-called technical resourcefulness. But such resourcefulness is aimed at only one thing - obtaining an estimated result. This is not right. The most important thing is to learn how to learn! For this, it is necessary to “pass” all the knowledge gained through oneself, and not rely on technology.
When conducting the exam at the points, and there are 77 of them in the region, there are attendants, managers and police officers, - said Larisa ZAKIROVA, Deputy Minister of Education and Science of the Amur Region. - All points are equipped, according to the order, with video cameras and metal detectors. It is forbidden to have electronic computers, mobile phones, audio-video equipment, various notes and records with you. As well as other items that interfere with the exam. Students should only have a passport and a gel pen with them. By the way, all the teachers on duty and the leader at the USE examination point must also comply with the regulations and be in the room without foreign things and objects.
This year, sensational glasses from a well-known company should go on sale - a headset for a smartphone that recognizes the movement of the eye and supplies visible objects with additional data. With their help, you can also run various programs, write texts, take photos and videos. The user of glasses will be able to take pictures with the help of natural blinking of the eye. Presumably, these glasses can be used in the everyday life of negligent students, whether they are schoolchildren or students: they wrote everything down on a flash card and look quietly at the exam. So teachers and educators need to be vigilant.
The fact is that the chain consists of links, each of which is less than the sensitivity threshold of the metal detector. The sensitivity threshold is the minimum target that a metal detector can detect.
Metal detectors perceive the chain not as a whole, but as a set of separate links. Questions from the same category: will the metal detector react to gold dust? Undoubtedly, it will be if you pour it in a slide or pour it into a box, but as soon as you distribute it on the table, the electromagnetic connection will be broken and the metal detector will not be able to detect individual grains of sand, regardless of their number. With a chain, the situation is similar. But as soon as it lies in the ground for some time and oxidizes, the metal detector will be able to detect it, since there will be an electronic connection between the links.
Why does my Quattro metal detector not see the chain, it works at a high frequency of 100 kHz, but does not see the chain?
Treasure metal detectors Quattro, Safari, E-Trac, Explorer, Sovereign, although they operate at frequencies from 1.5 to 100 kHz, the sensitivity is deliberately lowered for such small targets so that you do not have to dig up a lot of small items that are not of interest . Basically it will be garbage, pellets, primers from cartridges, scraps of foil and other trifles. High frequencies in these models are used for better discrimination of metals.
It is technically very difficult to create a metal detector that sees small chain links and at the same time would have a large detection depth. Therefore, metal detector models are divided into beach and treasure detectors.
Beach metal detectors designed specifically to search for small objects, including chains, for example, the Garrett ACE150, ACE250 or AT PRO models, have a maximum depth of 50-60 cm, but they have a high sensitivity to small objects, so they called beach.
There is a universal metal detector designed both for searching on the beach and for searching for treasures, coins and gold nuggets - X-Terra 705. This model is specially designed not only for searching for treasures, but also for gold. For more information about the X-Terra 705 model, you can find out from the videos on the KLADTV.RU website:
1. Metal detector X-Terra. Practice in the field.
2. "GEO" mode of X-Terra 705 metal detector.
3. How to set up X-Terra 705. Instructional video.
Complaining that the metal detector does not see the chain, think about whether this kind of fuss is worth your efforts? A chain is a light product, as a rule, its weight does not exceed 1-2 grams, but in the time that you spend on digging up small unnecessary debris in search of a chain, with another metal detector you can find several rings, and possibly a ring with a diamond.
There is a little trick, using which you can search for chains. If, during an instrumental search, you find a gold pendant or a cross, then most likely the chain on which it hung is somewhere nearby, since in most cases it was unfastened or torn from the neck. Therefore, when you find such things, examine the search area more carefully, without ignoring a single object from which the signal emanates. Turn the Threshold on so that it is audible, this will help you determine if there is a target under the coil.
Metal detector settings for searching for gold chains.
- Set the maximum sensitivity.
- Use concentric or mono coils with a small diameter of 9” or even 6”.
- Set discrimination mask to search for jewelry.
- Use tonal background.
- Be sure to use headphones.
P.S.
For what purposes do you plan to purchase a metal detector - this is the first question that everyone should ask themselves when they are going to buy a metal detector. Since the purpose of the metal detector determines its capabilities, sensitivity, detection depth, etc. Choose a detector: beach, treasure hunt, underwater, for searching for gold nuggets or universal.
Video:
Gold of Kapchigay
Beach search with a metal detector along the banks of rivers and reservoirs video. Excalibur 2 metal detector tips for finding finds. Gold on the beach. Metal detector beach search. Metal detector Excalibur 2 search in the lake. Beach gold. Author Rudolf Kavchik, Kazakhstan.
Underwater search in water with Excalibur metal detector. How to successfully search on the beach.
Expert advice
The security of a typical airport daily inspects the luggage of about two million people. Even when you do not have large metal objects with you, the metal detector works exactly when you pass. You are extremely surprised and an unpleasant inspection procedure awaits you. We offer our readers a list of items that security systems respond to.
aluminum wrap
Many manufacturers of chewing gum, candies and cigarettes use paper for wrapping instead of foil. The reason for this is the problems that passengers encountered when carrying such products. As a result, a negative attitude towards the brand.
What to do? In front of the metal detector, take absolutely everything out of your pockets to reduce the risk of being searched to zero.
Keys
We are talking about keys that are pulled out of a special case by pressing a button. When your bags are scanned, such an object looks like a knife. If you have such a key, be sure that you will be stopped and asked to show what you are carrying.
What to do? Keep your keys in your hand luggage so that you don't have to unpack the huge bags that you check in the luggage compartment.
hair bands
Yes Yes. The reason for your screening may be a simple bow. The reason is simple: many bows contain metal in their structure.
What to do? Lay out such tapes immediately before passing through the metal detector.
Small bottles of alcoholic drinks
There are clear rules about this. The bottle must contain no more than 3.4 ounces (100 ml) of hard liquor and be in the original container. You need to pack it in a transparent plastic bag, which is fastened with a zipper.
Glass snow globes
They cannot be carried in cabin baggage because they contain more than 3.4 ounces (100 ml) of liquid.
Bradley International Airport (Connecticut) was evacuated in October because security found a package containing such a glass ball. The airport resumed work only after a thorough study of the find.
What to do? If you are carrying such a souvenir, put it on top of your things and get ready for your luggage to be searched.
inhalers
As a rule, they contain more than 100 ml of liquid and are therefore not allowed in cabin baggage. But this ban does not apply to people who use an inhaler for medical reasons and cannot do without it during the flight.
What to do? Pack it in a transparent plastic bag and inform the security staff in advance that you are going to take this medication on board the aircraft. Make sure your aerosol is clearly labeled and described.
Bras
Manufacturers of metal detectors claim that they do not react to women's underwear, but many passengers say otherwise. As a rule, women are searched in a separate room. Needless to say, screening can be delayed and you miss your flight.
What to do? Try not to wear underwear with metal elements during the flight. And if there are such things in your luggage, then immediately prepare them for inspection.
Jars of peanut butter
Everything on the planet has its own form: liquid, solid or gaseous. Peanut butter is not one of them. If you put such a treat in your luggage, then you will be detained with a 100 percent probability.
What to do? If you're a big fan of peanut butter, stock up on sandwiches so you don't draw the attention of the guards and save your nerves.
We wish you pleasant flights, flights without delays and soft landings.