What is a dosimeter and how to use it. Dosimeters-radiometers: reviews. The principle of operation of dosimeters and radiometers. Dosimeter and its functions

How does a personal radiation meter work?

FROM From the very time that man began to use the energy contained in the atom, there has been a danger for all mankind, especially in heavily populated and developed countries. And you don’t have to go far for examples, this is the Chernobyl disaster, and the recent incident at the Japanese nuclear power plant Fukushima, and various accidents at enterprises working with radioactive materials, as well as radioactive waste, military tests, and so on. In this regard, for ordinary citizens there is a need to be able to determine the radiation situation themselves and make the right decision in case of an emergency. And here a special device can help you a lot - household radiation dosimeter . But for its correct and correct application, it is necessary to understand the measurement methods.

AT The first radiations appeared only in 1989, they began to be produced by the decision of the National Commission for Radiation Protection, until that moment all information on the radiation situation in a particular region was classified. The impetus for such a decision was the events in Chernobyl.

P The first dosimeters were made on the basis of discrete logic circuits and an analog interface. Modern radiometers already use microprocessor technology and use specialized controllers, as well as liquid crystal displays. However, both of them are based on the use, and what it is will be discussed below.

FROM A Geiger counter is a sealed chamber made of metal or glass and filled with an inert gas, usually argon or neon, and under low pressure (). Two electrodes (anode and cathode) are built into the chamber. For most domestic dosimeters based on the SBM-20 type counter, the cathode is almost the entire casing of the sensitive sensor, and the anode is just a thin wire inside it. And for Beta - 1 or Beta - 2 type meters, a multi-section system of electrodes and a more complex structure are characteristic, this allows you to register a wide variety of types of radiation. For such counters, the thickness of the working window (the area of ​​​​radiation based on alpha and beta particles) is typical, about 12 microns. Therefore, such end-type dosimeters are able to detect low-energy beta particles, and, if measurements are performed correctly, high-energy alpha particles, for this, measurements should be taken no further than 1–2 mm from the source of alpha radiation radiation.

H To make it easier to register a radioactive particle that has passed through the counter, a special load resistor is included in the power supply circuit of the dosimeter, through which changes in the circuit between the cathode and the anode are recorded. To ensure that the ionization in the chamber quickly stops after the discharge, and is ready to capture a new particle, there are two ways to achieve this. The first is based on stopping the voltage supply to the electrodes for a very short period of time, which inhibits further ionization, the second is based on the addition of alcohol or iodine to an inert gas, as well as a number of other materials. In this case, such an impurity, immediately after the discharge, contributes to a sharp decrease in the voltage at the cathode and anode, less than 300 volts, which also abruptly stops ionization and the counter becomes ready to register the next particle or radiation quantum. To supply high voltage to the electrodes, a special multiplier converter is used, powered by a simple 3-12 volt battery, and capable of delivering a voltage of 380-420 volts.

O The determination of the radiation level is a physical calculation by the microelectronics of the device of all radioactive particles passing through the registration chamber, be it beta particles or gamma radiation. The counting of such particles for a certain unit of time leads to the result that we can see on the display of the device.

P Personal dosimeters have the following options for calculating radiation, namely sieverts per hour (Sv/h) or roentgens per hour (R/h). In practice, data recorded in microroentgens and microsieverts (μR / h, μSv / h) are most often used, since it is these units of measurement that correspond. The normal value is considered to be the magnitude of the radioactive background of 0.2 μSv / h or 20 μR / h. Sieverts and Roentgens are interconnected by the following ratio 1 µSv = 100 µR.

D To measure beta particles, some modern counters, such as the professional radiometer or , measure the beta flux by how many beta particles pass through a 1 square centimeter window in one minute.

FROM It should be noted that the accuracy of measurements directly depends on the duration of the measurement, however, the long time for the determination of radioactivity will significantly complicate the use of the device, and if you are in an area with an increased background radiation, there is a danger of being there doing the measurement. Therefore, many modern ones have several time modes for conducting radiation measurements. To significantly reduce the measurement time without loss of accuracy, some dosimeters use several Geiger counters at once, for example, up to 4 pieces. The largest selection of time intervals in .

H to use correctly household geiger counter and dosimeter, the above is quite enough, but you should be interested in this topic in order to be more professional in interpreting the readings and the correctness of the measurements. Although, even a complete lack of understanding of the processes, if you detect a radioactive background significantly above the norm, should cause you concern, with the development of further emergency measures.

Many did not even think about what radiation is until in 1986 there was a disaster at the Chernobyl nuclear power plant. Soviet citizens have since begun to acquire radiation dosimeters. The accident at Fukushima, which happened not so long ago, once again confirmed that the mortal danger is not so far from us, and no one is immune from its harmful effects.

Radiation is the radiation that the human body has extremely negative impact, which can lead to death. The peculiarity of such radiation is that it is absolutely impossible to detect it with the naked eye. It lies in wait for a person in any place. This forces Russians to acquire dosimeters that can detect radiation.

On the modern market there is a large selection of devices that can measure radiation. A variety of models differ in design, feature set, cost. At the same time, all dosimeters have the same principle of operation and a set of basic capabilities. Therefore, before buying a device, you should think about the conditions under which it will be used.

Dosimeters are divided into two types:

• household;
• professional.

Both of these types have advantages and disadvantages.

Household dosimeters convenient because they have a compact size and ergonomic design, they can be put in your pocket or hand luggage. Their main advantage is their relatively low cost.

Household dosimeters are also convenient in that they can quickly provide information about exceeding the permissible level of radiation in a particular place. By signaling danger, it allows a person to leave this place as quickly as possible.

However, for the most part, such devices are able to determine only to what extent the environment is contaminated. But they are not able to determine what dose of radiation a person has accumulated, because the principle of operation of household dosimeters is based on counting the number of ionizing particles that have entered the device from the external environment. Household appliances are:

• threshold;
• non-threshold.

Professional radiation dosimeters compare favorably with household ones in that they can accurately determine what dose of radiation a person has accumulated. In addition, they have high sensitivity and measurement accuracy. These devices are mainly used by narrow specialists, as well as people who, on duty, are in the danger zone.

Professional dosimeters do not have an original design and are not compact. However, in terms of their characteristics, they significantly exceed the most advanced models, but their cost is quite high.

How to choose a radiation dosimeter

Experts advise: do not choose a device that has a large number of functions. Using it at home is completely useless, because hardly anyone will measure gamma, alpha and beta radiation separately. You can, of course, choose a device that measures neutron radiation, but its cost is very high. It is best to use a portable household dosimeter type "Rad Ex". It has the following benefits:

• ease of use;
• small size;
• reliability;
• high measurement accuracy.

Particular attention should be paid to ease of use and simplicity, because sometimes there are no extra minutes to take a measurement, and a decision must be made immediately. A portable household dosimeter can measure radiation in 45 seconds. Moreover, it immediately shows how much excess radiation the object has over the natural fund.

You should also pay attention to degree of error. This indicator is extremely important for low backgrounds, and also if the device is used in frost or outdoors, because at low temperatures the dosimeter often shows inaccurate data.

The principle of operation of the dosimeter

Using this device is very simple. You can examine your apartment, summer cottage, office, picked berries and mushrooms, etc. You should know that the natural gamma background is 10 - 30 microroentgen per hour. If these figures are exceeded, you need to urgently call the Ministry of Emergency Situations so that they send the necessary specialist.

To obtain the most accurate indicators of the radiation background in the room, you should at least three measurements at one point. After that, you need to walk around the entire room, measuring the radioactive background of various objects.

If any object exceeds the normal radiation background by 1 - 2 microroentgen per hour, you need to get rid of it immediately, because such an additional source of radiation is unlikely to be a joy after that. Such a small dose, of course, is not capable of causing serious harm, but the doses of radiation that a person receives throughout life can accumulate in the body, threatening health with serious problems.

Conclusion

Radiation is not visible, it is impossible to see it, but the consequences after radiation exposure appear almost instantly. If you suspect that in some particular place there may be background radiation exceeded, you need to purchase a radiation dosimeter. It can be used to examine the premises, building materials, food products for contamination with radioactive elements.

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 flux of ionizing radiation 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. The mass of household appliances is 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. Such a system is often 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).

see also

• Dubovsky, Boris Grigorievich - creator of Soviet dosimeters

Links

• Photos of some Soviet dosimeters (in the "Dosimeters" section).
• Testing and comparative analysis of household dosimeters

Photo

Wikimedia Foundation. 2010 .

See what "Dosimeter" is in other dictionaries:

Dosimeter … Spelling Dictionary

dosimeter- A device or installation for measuring ionizing radiation, designed to obtain measuring information about the exposure dose and exposure dose rate of photon radiation and (or) about 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 fundamentally different types of D.: D., which measures the dose accumulated during a certain time of stay in conditions of increased radiation loads, and D., which shows 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

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 flux of ionizing radiation 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 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 of a digital indicator: from a simple LED to a 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.

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.

In the article "" we examined the nature of radiation - what is radiation(ionizing radiation) and radioactivity, concept radionuclides and half-life, the effect of radiation on the human body, and talked a little about the radioactive objects around us.

What does a dosimeter measure and what does it not measure?

The dosimeter measures the dose rate of ionizing radiation directly in the place where it is located. The main purpose of a household dosimeter is to measure the dose rate in the place where this dosimeter is located (in the hands of a person, on the ground, etc.) and thereby check suspicious objects for radioactivity. However, most likely you will be able to notice only fairly large increases in dose rate.

Therefore, an individual dosimeter will help, first of all, those who often visit areas contaminated as a result of the Chernobyl accident (as a rule, all these places are well known).

In addition, such a device can be useful in an unfamiliar area remote from civilization (for example, when picking berries and mushrooms in rather “wild” places), when choosing a place for building a house, for preliminary testing of imported soil during landscape improvement. In these cases, it will be useful only for very significant radioactive contamination. Not very strong, but nevertheless unsafe pollution is very difficult to detect with a household dosimeter.

With regard to the possibility of checking the compliance of radiation parameters with established standards using a household dosimeter, the following can be said: ozic indicators (dose rate in rooms, dose rate on the ground) for individual points can be checked, but it is very difficult to examine the entire room with a household dosimeter and achieve confidence that a local source of radioactivity has not been missed.

It is almost useless to try to measure the radioactivity of food or building materials with a household dosimeter. The dosimeter can only detect very much contaminated products or building materials, the content of radioactivity in which exceeds the permissible norms by tens of times. For products and building materials, it is not the dose rate that is normalized, but the content of radionuclides, and the dosimeter is fundamentally does not allow measure this parameter.

How to use a dosimeter correctly?

Use the dosimeter in accordance with the instructions supplied with it.

It is also necessary to take into account that in any radiation measurements there is a natural radiation background. Therefore, first, a dosimeter measures the background level characteristic of a given area of ​​the terrain (at a sufficient distance from the alleged source of radiation), after which measurements are taken already in the presence of the alleged radiation source. The presence of a stable excess above the background level may indicate the detection of radioactivity.

The fact that the dosimeter readings in the apartment are more 1,5 — 2 times than on the street, nothing out of the ordinary. In addition, it must be taken into account that when measuring at the “background level” in the same place, the device can show, for example, 8, 15 and 10 μR / h. Therefore, to obtain a reliable result, it is recommended to take several measurements and then calculate the arithmetic mean. In our example, the average will be (8+15+10)/3 = 11 µR/hour.

What are dosimeters?

On sale can be found as household, and professional dosimeters. The latter have a number of fundamental advantages. However, these devices are quite expensive (ten or more times more expensive than a household dosimeter), and situations where these advantages can be realized are extremely rare in everyday life. Therefore, you need to purchase a household dosimeter.

Special mention should be made of radiometers for measuring radon activity: although they are only in professional performance, but their use in everyday life can be justified.

The vast majority of dosimeters are directly showing, i.e. with their help, you can get the result immediately after the measurement. There are also indirect-reading dosimeters that do not have any power supply and indication devices, and are extremely compact (often in the form of a key fob). Their purpose is individual dosimetric control at radiation-hazardous objects and in medicine. Since such a dosimeter can be recharged or its readings read only with the help of special stationary equipment, it cannot be used to make operational decisions.

Dosimeters are non-threshold and threshold. The latter make it possible to detect only the excess of the standard radiation level preset by the manufacturer according to the “yes-no” principle and due to this they are simple and reliable in operation, they cost about 1.5-2 times cheaper than non-threshold ones. As a rule, non-threshold dosimeters can also be operated in the threshold mode.

Household dosimeters mainly differ in the following parameters:

• types of detected radiation - only gamma, or gamma and beta;
• type of detection unit - gas discharge counter (also known as a Geiger counter) or scintillation crystal/plastic; the number of gas-discharge counters varies from 1 to 4;
• location of the detection unit - remote or built-in;
• the presence of a digital and / or sound indicator;
• time of one measurement - from 3 to 40 seconds;
• the presence of certain modes of measurement and self-diagnosis;
• dimensions and weight;
• price, depending on the combination of the above parameters.

Examples:

	Household dosimeter-radiometer of gamma and beta radiation ANRI-01-02 "Pine". Price — $10-30 Detector type — 2 built-in gas-discharge counters. Digital indicator on liquid crystals The time spent on 1 measurement is 20 seconds. Dimensions of the device 133x82x45 mm, weight 350 g.
	Professional radiometer SRP-88, designed to search for and detect sources of gamma radiation (for example, when examining scrap metal). The estimated cost is $1,500. Detector type - scintillation crystal, detection unit - remote. Digital and pointer indicators. The time spent on 1 measurement is from 1 to 10 seconds. The mass of the device is 2.2 kg.

What should I do if the dosimeter goes off scale or its readings are unusually high?

• Make sure that when the dosimeter is moved away from the place where it "rolls over", the readings of the device return to normal.
• Make sure that the dosimeter is working properly (most devices of this kind have a special self-diagnosis mode).
• Short circuits, battery leaks, strong external electromagnetic fields can partially or completely disrupt the normal operation of the electrical circuit of the dosimeter. If possible, it is desirable to duplicate the measurements using another dosimeter, preferably a different type.

If you are sure that you have found a source or site of radioactive contamination, IN NO EVENT should you try to get rid of it yourself (throw it away, bury it or hide it). You should somehow mark the place of your find, and be sure to report it to the services (for example, MosNPO Radon in Moscow), whose duties include the detection, identification and disposal of orphan radioactive sources. Read also.