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What is the background of the dosimeter counter. Instruments that measure radioactivity

Dosimeter- this is a device for measuring the dose or dose rate of ionizing radiation received by the device (and those who use it) for a certain period of time, for example, for a period of stay in a certain territory or for a work shift. The measurement of the above quantities is called dosimetry.

Sometimes "dosimeter" is not quite accurately called radiometer- a device for measuring the activity of a radionuclide in a source or sample (in the volume of liquid, gas, aerosol, on contaminated surfaces) or the density of the flux of ionizing radiation to check suspicious objects for radioactivity and assess the radiation situation in this place V this moment. The measurement of the above quantities is called radiometry. X-ray meter- a kind of radiometer for measuring the power of gamma radiation.

Household appliances, as a rule, combined, have both modes of operation with switching "dosimeter" - "radiometer", light and (or) sound alarms and a display for reading measurements. The mass of household items is from 400 to several tens of grams, the size allows you to put them in your pocket. Some modern models can be put on the hand like a watch. Time of continuous operation from one battery from several days to several months.

The measurement range of household radiometers, as a rule, is from 10 microroentgen per hour to 9.999 milliroentgen per hour (0.1-99.99 microsievert per hour), measurement error up to ±30%

detector(a sensitive element of a dosimeter or radiometer, which is used to convert phenomena caused by ionizing radiation into an electrical or other signal that is easily accessible for measurement) can be an ionization chamber, a Geiger counter, a scintillator, a semiconductor diode, etc.

IONIZATION CHAMBER

An ionization chamber is a gas-filled sensor designed to measure the level of ionizing radiation.

Measurement of the radiation level occurs by measuring the level of gas ionization in the working volume of the chamber, which is located between the two electrodes. A potential difference is created between the electrodes. In the presence of ions in the gas, an ion current occurs between the electrodes, which can be measured. The current, other things being equal, is proportional to the rate of occurrence of ions and, accordingly, the dose rate of radiation.

In a broad sense, ionization chambers also include proportional counters and Geiger-Muller counters. These devices use the phenomenon of the so-called gas amplification due to secondary ionization - in a strong electric field, the electrons that have arisen during the passage of an ionizing particle are accelerated to an energy sufficient to ionize gas molecules in turn. In a narrow sense, an ionization chamber is a gas-filled ionization detector operating outside the gas amplification mode.

The gas that fills the ionization chamber is usually an inert gas (or a mixture thereof) with the addition of a readily ionizable compound (usually a hydrocarbon, such as methane or acetylene). Open ionization chambers (eg ionization smoke detectors) are filled with air.

Ionization chambers are current (integrating) and pulsed. In the latter case, fast moving electrons are collected on the anode of the chamber (in a time of about 1 μs), while slowly drifting heavy positive ions do not have time to reach the cathode during this time. This makes it possible to register individual pulses from each particle. A third electrode is introduced into such chambers - a grid located near the anode and shielding it from positive ions.

GEIGER-MUELLER COUNTER

A Geiger counter, a Geiger-Muller counter is a gas-discharge device for counting the number of ionizing particles that have fallen into it. It is a gas-filled capacitor that breaks through the passage of an ionizing particle through a volume of gas. Additional electronic circuit provides the meter with power (as a rule, not less than 300V), provides, if necessary, extinguishing the discharge and counts the number of discharges through the meter.

Geiger counters are divided into non-self-extinguishing and self-extinguishing (not requiring an external discharge termination circuit). The sensitivity of the counter is determined by the composition of the gas, its volume, and the material (and thickness) of its walls.

In household dosimeters and radiometers manufactured in the USSR and Russia, 400-volt meters are usually used:
- "SBM-20" (in size - a little thicker than a pencil), SBM-21 (like a cigarette filter, both with a steel case, suitable for hard gamma and beta radiation);
- "SI-8B" (with a mica window in the body, suitable for measuring soft beta radiation).

The widespread use of the Geiger-Muller counter is explained by its high sensitivity, the ability to register various kinds of radiation, and the comparative simplicity and low cost of installation. The counter was invented in 1908 by Geiger and improved by Müller.

Cylindrical Geiger-Muller counter consists of metal tube or a glass tube metallized from the inside and a thin metal thread stretched along the axis of the cylinder. The filament is the anode, the tube is the cathode. The tube is filled with a rarefied gas, in most cases the noble gases argon and neon are used. A voltage of about 1500 V is created between the cathode and anode.

The operation of the counter is based on impact ionization. Gamma - quanta emitted by a radioactive isotope, falling on the walls of the counter, knock out electrons from it. Electrons, moving in the gas and colliding with gas atoms, knock electrons out of atoms and create positive ions and free electrons. The electric field between the cathode and the anode accelerates the electrons to energies at which impact ionization begins. There is an avalanche of ions, and the current through the counter increases sharply. In this case, a voltage pulse is formed on the resistance R, which is fed to the recording device. In order for the counter to be able to register the next particle that fell into it, the avalanche charge must be extinguished. This happens automatically. At the moment the current pulse appears on the resistance R, a large voltage drop occurs, so the voltage between the anode and cathode decreases sharply and so much that the discharge stops and the counter is ready for operation again.

An important characteristic counter is its efficiency. Not all gamma-ray photons that hit the counter will give secondary electrons and will be registered, since the acts of interaction of gamma rays with matter are relatively rare, and some of the secondary electrons are absorbed in the walls of the device without reaching the gas volume.

The efficiency of the counter depends on the thickness of the walls of the counter, their material and the energy of gamma radiation. The most efficient are counters whose walls are made of a material with a large atomic number Z, since this increases the production of secondary electrons. In addition, the walls of the counter must be sufficiently thick. The wall thickness of the counter is chosen from the condition of its equality to the mean free path of secondary electrons in the wall material. With a large wall thickness, the secondary electrons will not pass into the working volume of the counter and the appearance of a current pulse will not occur. Since gamma radiation weakly interacts with matter, the efficiency of gamma counters is usually also low and amounts to only 1-2%. Another disadvantage of the Geiger-Muller counter is that it does not provide the ability to identify particles and determine their energy. These shortcomings are absent in scintillation counters.

SCINTILLATORS

Scintillators are substances that have the ability to emit light upon absorption of ionizing radiation (gamma quanta, electrons, alpha particles, etc.). As a rule, the emitted number of photons for of this type radiation is approximately proportional to the absorbed energy, which makes it possible to obtain the energy spectra of the radiation. Nuclear research scintillation detectors are the main application of scintillators. In a scintillation detector, the light emitted during scintillation is collected on a photodetector (as a rule, this is a photomultiplier photocathode - PMT, photodiodes and other photodetectors are used much less often), converted into a current pulse, amplified and recorded by one or another recording system.

The constant scandals around the discovery of radiation sources in large Russian cities make many people think about the radiation safety of their families. And it is right. For example, recently in one of the Moscow apartments, 3 sources of ionizing radiation were discovered at once, the most powerful of which emitted 250,000 micro-roentgens per hour! It was a real mini-Chernobyl in an ordinary apartment!

Here's what a home dosimeter can come in handy for

It all started with the fact that a Muscovite living in an ordinary house on Korovinskoye Highway No. 13 decided to examine her apartment with a conventional dosimeter. It was the right decision, because under the ceiling a miniature device literally went off scale, showing a thousand micro-roentgens per hour! The hostess called the Ministry of Emergency Situations, and the Radon task force that arrived at the scene confirmed the indicators of the household dosimeter. Radiation near the ceiling exceeded 850 μR/h. Fortunately, at the level of human growth (about a meter from the ceiling), the gamma background was within the natural range - 30 μR / h, otherwise the consequences for the residents of the apartment would have been fatal. Specialists had to open a non-residential apartment on the floor above. Her elderly mistress had been in the hospital for a long time. In an empty apartment in the bottom drawer of the closet, three powerful sources of radiation were discovered at once. The most dangerous was an ordinary compressed tablet, resembling dry alcohol, on the surface of which the power of gamma radiation was 250,000 microroentgens per hour, that is, the norm was exceeded ten thousand times! The box also contained a hermetically sealed glass ampoule with unknown contents, which gave 160 microR/h, and a wooden box that “radiated” 60 microroentgens.

All found sources were immediately taken out by specialists and buried. The owner of the ill-fated apartment died just a few days later, so it remains a mystery to specialists how such powerful sources of radiation ended up in an ordinary Moscow five-story building. According to neighbors, an elderly woman, the owner of a makeshift radioactive burial ground, was fond of antique objects, picked them up from landfills and carried them home. According to another version, she once worked at a secret research institute, and these items were recently given to her by a former colleague. A criminal case was opened. What harm was done to the neighbors of the old woman, one can only guess, but she herself gave her life for dangerous finds.

A household portable dosimeter will help you quickly assess the radioactive situation in your apartment.

This incident, for sure, made many think about whether they store deadly antiquities, antiques, and whether any of the neighbors indulge in a dangerous hobby. This question is not idle, because every year up to 80 objects of the strongest radioactivity are destroyed in Moscow. Given the harm that radiation does to human health, causing malignant tumors, DNA errors, mutations and deformities, infertility, everyone should check the radiation background in their home. The easiest way, with which you can measure both the level of radiation in the apartment, and check the safety of an individual item. It is not expensive, and even a child can use it, no special knowledge is required. You can take the dosimeter with you to the market, on a trip, to the country house, to pick berries and mushrooms, because you can meet radiation anywhere, and you should always be prepared for this. Short-term exposure to small radiation is not dangerous, but in no case should you constantly live near contaminated objects. Young children, whose fragile bodies are still growing, suffer especially from radiation. For them, even a small dose of radiation can be deadly and cause serious developmental disabilities.

How to choose a good dosimeter?

The specialists of our website www.site give following tips: first of all, do not chase after big amount functions in the device. In everyday life, they are practically useless. It is unlikely that you will ever need to measure alpha, beta or gamma radiation separately. Of course, you can even buy a device that measures neutron radiation, but the price of such devices is huge, and there is no benefit from them. It is better to use portable household dosimeters like "RadEx". It is characterized by ease of use, reliability, miniature size and very accurate measurements - that is, it has all the qualities of a good household dosimeter.

Particular attention should be paid to simplicity and ease of use, because it may often not be possible to take measurements within a few minutes, the decision must be made quickly. RadEx will give the result in just 45 seconds! In addition, the dosimeter will immediately show the excess of the object's radiation over the natural background, that is, you do not have to make complex calculations in your mind, which will save you time and nerves.

Dosimeter "RadEx" can be used to examine food.

How to use a dosimeter?

As we have already noted, using a household dosimeter is very simple. You can inspect your apartment, office, suburban area fish caught in fishing, collected mushrooms and berries, etc. To begin with, remember that the natural gamma background for Moscow is from 10 to 30 microroentgens per hour. If these values are exceeded, you need to call the Ministry of Emergency Situations, and they will already send specialists of the profile you need. In order to obtain the most accurate data on the radiation background in the room, it is necessary to carry out at least three measurements at one point. Then start walking around the room, measuring the radioactive background of various objects. If the old grandfather clock exceeds the normal radiation background by at least 1-2 microroentgens per hour, then think about whether you need an additional source of radiation in your own apartment, because there are a lot of natural sources of radiation around, from which you can’t escape and you can’t protect yourself. A single dose of a few micro-roentgens, of course, is not lethal, but the doses of radiation that we receive throughout life are summed up, accumulating in our body and threatening serious damage to health.

Dosimeter

Outdated household dosimeter-radiometer "Sosna" (USSR, 1992). The battery compartment is ajar. Shows 16 microroentgen/hour.

Dosimeter- a device for measuring the effective dose or power of ionizing radiation over a certain period of time. The measurement itself is called dosimetry.

Sometimes "dosimeter" is not quite accurately called radiometer- a device for measuring the activity of a radionuclide in a source or sample (in the volume of liquid, gas, aerosol, on contaminated surfaces) or the density of the ionizing radiation flux to check for radioactivity of suspicious objects and assess the radiation situation in a given place at a given moment.
The measurement of the above quantities is called radiometry.

Household appliances, as a rule, combined, have both modes of operation with switching "dosimeter" - "radiometer", light and (or) sound alarms and a display for reading measurements. Weight household appliances from 400 to several tens of grams, the size allows you to put them in your pocket. Some modern models can be worn on the wrist like a watch. Time continuous work from one battery from several days to several months.

The measurement range of household radiometers is usually from 10 to 10 thousand microroentgen per hour (0,1 - 100 microsievert per hour), measurement error ±30%.

In the USSR, household dosimeters became most widespread after the Chernobyl accident in 1986. Until that time, dosimeters were used only for scientific or military purposes.

Whole body dosimetry counters

BOMAB

The Bomab (The BOttle MAnikin Absober) is a phantom developed in 1949 and has since been adopted in North America, if not worldwide, as the industry standard (ANSI 1995) for calibrating dosimeters used for whole body counting. .

The phantom consists of 10 polyethylene bottles, either cylinders or elliptical balloons, which are its head, neck, chest, abdomen, thighs, legs and arms. Each section is filled with a radioactive solution in water, the radioactivity of which is proportional to the volume of each section. This mimics the uniform distribution of the material throughout the body.

Examples of radioactive isotopes used to calibrate calibration efficiency: edit] Lung counter

Lung Counter is a system designed to measure and count radiation from radioactive gases and aerosols inhaled by a person and insoluble enough in body tissues to leave the lungs for several weeks, months or years. Consists of a radiation detector or detectors and their associated electronics. The detectors imitate the shape, density and chemical composition of the tissue of the lungs and surrounding organs. The cavities in the detectors are filled with the investigated radioactive gas or aerosol. Often, such a system is located in the lower floors of rooms (to protect against the hadronic component of the cosmic background) and is surrounded by protection from background gamma radiation (thick walls made of steel, lead, and other heavy materials) and neutron radiation (cadmium, boron, polyethylene).

Since the lung counter is primarily used to measure radioactive substances that emit low-energy gamma or x-rays, the phantom used to calibrate the system must be anthropometric. Such a phantom of the human body was developed, for example, at the Livermore National Laboratory. E. Lawrence (Torso Phantom).

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Synonyms:

See what "Dosimeter" is in other dictionaries:

Dosimeter … Spelling Dictionary

dosimeter- A device or installation for measuring ionizing radiation, designed to obtain measuring information on the exposure dose and exposure dose rate of photon radiation and (or) on the energy carried by ionizing radiation ... ... Technical Translator's Handbook

dosimeter- a, m. dosimètre m., German. Dosimeter. A device for measuring the dose of radioactive radiation. Photoelectric dosimeter. Personal dosimeter. ALS 2. Today they scare us with everything in the world, And you can survive in our days completely. And I live: I walk in a bulletproof vest, ... ... Historical Dictionary of Gallicisms of the Russian Language

DOSIMETER- (D.) a device for monitoring radiation exposure. There are two fundamental different types D.: D., measuring the dose accumulated over certain time stay in conditions of increased radiation loads, and D., showing the excess of the permissible ... Ecological dictionary

dosimeter- and an outdated dosimeter ... Dictionary of pronunciation and stress difficulties in modern Russian

DOSIMETER, a device for measuring the dose of radiation or related quantities. There are dosimeters for one type of radiation (for example, neutron dosimeters, g dosimeters) and for mixed radiation. The main parts of the dosimeter are the particle detector and… … Modern Encyclopedia

DOSIMETER, a device for measuring the dose of RADIATION, usually a pocket ELECTROSCOPE. The quartz fiber is charged and then viewed against a scale. The measure of its deviation during irradiation corresponds to the level of radiation with which it ... ... Scientific and technical encyclopedic dictionary

Ex., number of synonyms: 5 biodosimeter (1) gamma dosimeter (1) microdosimeter ... Synonym dictionary

Dosimeters-radiometers are multifunction devices, which are designed to determine gamma radiation. In this case, the device determines Some models are capable of measuring neutron radiation. Dosimeters are used primarily in the nuclear industry. However, there are many household modifications on the market.

Dosimeters are also used to control the quality of raw materials and food products. They are also used in medicine. Additionally, for the determination of X-rays, they are found in the metallurgical industry. In order to familiarize yourself with dosimeters in more detail, you should first consider the design of the model.

Simple model device

The main element of any dosimeter is considered to be a counter. The specified component works thanks to the blocking generator. The devices also use a voltage multiplier. In some cases, it is installed in a two-pin type. Capacitors are most often used precisely separating. Single vibrators in devices are used low-frequency.

Directly, the control units in terms of parameters are quite different. The functional part of the device depends on the manufacturer. A converter is also used in the devices. Batteries are most often installed with a small capacity. Dosimeters also have a resonator and a modulator, which are located near a compact microcontroller.

The principle of operation of the device

The principle of operation of dosimeters and radiometers is based on the distortion of the limiting frequency of gamma radiation. The X-ray particles are directly captured by the counter. Next, the signal is transmitted to the blocking generator. In order for the resonator to activate, a converter is required. The single vibrator in this case provides high sensitivity of the device.

The resonator, in turn, is responsible for the signal transmission speed. The microcontroller receives data on gamma radiation through a modulator. Then they are immediately displayed on the display. Direct voltage to the microcontroller is supplied through the battery.

Reviews about "SOEKS-01M"

These dosimeters-radiometers are highly sensitive. If we talk about their design features, it is important to note that the models have only one counter. The equivalent power of the presented device is as much as 0.1 microns per hour. If you believe customer reviews, then the indicated model determines the beta-radiation flux density quite quickly. The blocking generator in the device is used with an output winding. The energy dependence of the presented model is insignificant. The quality of the voltage multiplier deserves special attention. In this case, the operating mode is set only for 5 seconds.

Opinion of buyers about the model "SOEKS Defender"

These dosimeters-radiometers are more in demand in the metallurgical industry. If you believe the feedback from consumers, then the blocking generator for the models is quite powerful. The ambient dose parameter in this case is 0.1 microns.

The flux density of beta radiation is determined quickly. This model has only one detector chamber. It is also important to note the compact dimensions of the device. In this case, the display backlight is provided. The case is quite durable. This device can be used even at a temperature of -20 degrees.

Reviews about MKS-05

This compact dosimeter-radiometer reviews from consumers deserve mostly positive. However, the device still has disadvantages. First of all, it should be noted that the ambient dose rate is low at the level of 0.3 microns per hour. Also, the device suffers from reduced sensitivity. However, the advantages should include a high-quality counter.

This model also uses two blocking generators. If you believe the customer reviews, then the display system it provides is quite high quality. The operating mode is activated in the device in 4 seconds. Dosimeter-radiometer MKS-05 has an automatic restart function.

According to the documentation for the product, the capacitors of the model are of a dividing type. Given this fact, the device is able to boast of a high signal transfer rate. Directly the scoreboard is installed with backlight. Indication of the degree of battery charge in this case is provided. If necessary, the dosimeter can be connected to a personal computer.

Features of the MKS-01CA1M model

The MKS-01CA1M dosimeter-radiometer is quite simple to use. In this case, the manufacturer provides a backlight for the display. If you believe the opinion of consumers, then the flux of beta radiation is determined quickly. Directly, the ambient dose rate is 0.1 microns per hour. The presented model uses only one blocking generator.

The counter has a rather high sensitivity, so the error of the indicated device gives a small one. Deserves special attention high setting flux density at the level of 20 ah. If you believe customer reviews, then the operating mode in the presented model is activated after 6 seconds. In this case, there is an indication of the units of measurement. The MKS-01CA1M dosimeter-radiometer also has the function of continuous operation.

Model "ISS Aquantum"

Dosimeter radiometer "MKS Aquantum" is quite in demand in the nuclear industry. If you believe the reviews of experts, then the presented model determines the power of the beta radiation flux with high accuracy. Her case is compact, and the device is quite simple to use.

If we talk about design features, it is important to note that there are two blocking generators in the device. The single vibrator itself is of the low-frequency type. The control unit, in turn, is used two-channel. According to customer reviews, the model has measurements. Also at this appliance There is an automatic restart option.

Features "Ecotest"

These household dosimeters-radiometers have recently been in great demand. The model has only one blocking generator. Directly, the voltage multiplier is used single-pin. Thus, the battery in the device is not quickly discharged. If you believe customer reviews, then the operating mode in the presented configuration is activated in 5 seconds.

If we talk about the main parameters, then first of all, the high dose rate at around 22 AH deserves attention. The range of gamma radiation detected by the device is quite wide. The model has only one counter. Directly the resonator is set to high sensitivity. The presented model is able to determine the flux density of beta radiation. It is also important to mention that her scoreboard is highlighted.

Model DKS-96

The dosimeter-radiometer DKS-96 is characterized by large limits of relative measurement error. If you believe the reviews of experts, the blocking generator of the model is quite high quality. In this case, the signal is transmitted very quickly. The direct beta-radiation flux parameter is 0.5 microns. The model has a continuous measurement function. The device also has a detector chamber. The dose rate of the model is 21 AH.

The operating mode turns on in 4 seconds. The voltage multiplier is of the single-terminal type, and accumulator battery does not dissipate quickly. The control unit of the device is designed for two channels. To determine the flow of gamma radiation, the device can be used. The device has an automatic restart function. The model has an indication of the degree of battery charge. According to many consumers, the body of the dosimeter is very compact, but the readings on the display are clearly visible.

Dosimeter- a device for measuring the equivalent dose of ionizing radiation over a certain period of time (dose rate). The measurement itself is called dosimetry.

Sometimes "dosimeter" is not quite accurately called radiometer- a device for measuring the activity of a radionuclide in a source or sample (in the volume of liquid, gas, aerosol, on contaminated surfaces) or the density of the ionizing radiation flux to check for radioactivity of suspicious objects and assess the radiation situation in a given place at a given moment.
The measurement of the above quantities is called radiometry.

Household appliances, as a rule, combined, have both modes of operation with switching "dosimeter" - "radiometer", light and (or) sound alarms and a display for reading measurements. Mass of household appliances from 400 to several tens of grams [ ] , the size allows you to put them in your pocket. Some modern models can be worn on the wrist like a watch. Time continuous operation from one battery from several hours (instruments with color LCD screens) to several months.

The measurement range of household radiometers is usually from 10 to 10 thousand microroentgen per hour (0,1 - 100 microsievert v hour), measurement error ±30%.

In the USSR, household dosimeters became most widespread after the Chernobyl accident in 1986. Until that time, dosimeters were used only for scientific or military purposes.

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Types of dosimeters

Professional. In addition to measuring the dose of radiation, they can measure the activity of a radionuclide in any sample: an object, liquid, gas, etc. Dosimeters-radiometers can measure the flux density of ionizing radiation to check for radioactivity of various objects or to assess the radiation situation on the ground. Modern professional dosimeters-radiometers allow, by the nature and energy spectrum of the radiation, to immediately issue a conclusion about which isotope emits. As a rule, they have a separate special detector for alpha radiation. Separately, special devices for dosimetry of neutrons, protons, etc. can be distinguished.
Domestic. Relatively inexpensive individual dosimeters that measure the dose rate of ionizing radiation at the household level with a low measurement accuracy - to check food, building materials, the radiation situation at home, etc. Household dosimeters are mainly characterized by the following parameters. Types of detected radiation - only gamma, or gamma and hard beta, very rarely soft beta and alpha. Type of ionizing radiation detection unit - the cheapest indicators use a special diode, high-quality mid-level dosimeters-radiometers use one or more gas-discharge counters (also known as a Geiger counter, or an improved analogue, a Geiger-Muller counter; as a rule, in domestic dosimeters counters such as SBM-20, SBT, etc. are used), the most expensive household dosimeters can use a scintillation crystal / plastic, as well as a separate sensor for recording alpha and soft beta radiation; the number of gas-discharge counters varies from 1 to 4. The location of the detection unit is usually built-in. Availability digital indicator: from simple LED to the color LCD display. The presence of a sound indicator: from a simple tweeter speaker to the ability to pronounce readings with a voice. The time of one measurement is from 3 to 40 seconds. The measurement limit is relatively small. Small dimensions and weight.
Individual. Shows the accumulated dose.
Industrial. It is installed next to objects such as nuclear power plants for continuous monitoring of the radiation situation.
Military. Designed for use in military operations, in particular for work in the conditions of a nuclear explosion.

Whole body dosimetry counters

TBMA

Bomab (The BOttle MAnikin Absober) is a phantom developed in 1949 and has since been adopted in North America, if not worldwide [ ] as an industry standard (ANSI 1995) for calibrating dosimeters used for whole body counting.