Units of measurement of radiation. Units of measurement of penetrating radiation

Since the middle of the last century a new word has come to science - radiation. Its discovery has revolutionized the minds of physicists from all over the world and has allowed the rejection of some Newtonian theories and making bold assumptions about the structure of the universe, its formation and our place in it. But this is all for specialists. The inhabitants only sigh and try to put together such scattered knowledge about this subject. Complicating the process is the fact that there are quite a few units of radiation measurement, and all of them are eligible.

Terminology

The first term to be met with is radiation itself. This is the name of the process of radiation by any substance of minute particles, such as electrons, protons, neutrons, helium atoms, and others. Depending on the type of particle, the radiation properties differ from each other. Radiation is observed either in the decomposition of substances into simpler ones, or in their synthesis.

Units of radiation are conditional concepts that indicate how many elementary particles are released from a substance. At the moment, physics operates with seven different units and their combinations. This allows us to describe the various processes that take place with matter.

Radioactive decay is an arbitrary change in the structure of unstable nuclei of atoms by the release of microparticles.

The decay constant is a statistical concept predicting the probability of the atom breaking down for a certain period of time.

The half-life is the time period during which half of the total amount of the substance disintegrates. For some elements, it is calculated in minutes, and for others - for years, and even for decades.

What is the measurement of radiation

Units of radiation are not the only ones used to assess the properties of radioactive materials. In addition, they use such quantities as:
- activity of the source of radiation;
- flux density (the amount of ionizing particles per unit area).

In addition, there is a difference in the description of the effect of radiation on living and nonliving objects. So, if the substance is not alive, then the concepts apply to it:

- absorbed dose;
- exposure dose.

If the radiation has affected the living tissue, then use the following terms:

- equivalent dose;
- effective equivalent dose;
Dose rate.

Units of radiation measurement are, as already mentioned above, conditional numerical values adopted by scientists to facilitate calculations and construct hypotheses and theories. Perhaps, that is why there is no single generally accepted unit of measurement.

Curie

One of the units for measuring radiation is the curie. It does not belong to the system (it does not belong to the SI system). In Russia it is used in nuclear physics and medicine. The activity of the substance will be equal to one curie, if in one second it will have 3.7 billion radioactive decays. That is, we can say that one curie is equal to three billion seven hundred million becquerels.

This number was due to the fact that Maria Curie (who introduced the term to science) conducted her experiments on radium and took as a basis its rate of decay. But over time, physicists decided that the numerical value of this unit is better tied to another - Becquerel. This allowed to avoid some errors in mathematical calculations.

In addition to curies, it is often possible to find multiples or fractional units, such as:
- megacuries (3.7 on 10 in the 16th degree of becquerels);
- килокюри (3,7 thousand billion becquerels);
- millicuries (37 million becquerels);
- microcurie (37 thousand becquerels).

With the help of this unit, one can express the volume, surface or specific activity of a substance.

Becquerel

The unit for measuring the dose of Becquerel radiation is systemic and is included in the International System of Units (SI). It is the simplest, because the activity of radiation in one becquerel means that in the substance there is only one radioactive decay per second.

It got its name in honor of Antoine Henri Becquerel, the French physicist. The name was approved at the end of the last century and is still in use. Since this is a fairly small unit, decimal consoles are used to designate activity: kilo, milli-, micro- and others.

Recently, along with Becquerels, such extrasystem units as Curie and Rutherford began to be used. One reserve is equal to one million becquerels. In the description of bulk or surface activity, one can find the notations of becquerel per kilogram, becquerel per meter (square or cubic) and their various derivatives.

X-ray

Unit of measurement of radiation X-ray also is not systemic, although it is used everywhere to denote the exposure dose of the obtained gamma radiation. One X-ray is equal to a dose of radiation at which one cubic centimeter of air at a standard atmospheric pressure and zero temperature carries a charge equal to 3.3 * (10 * -10). This is equal to two million pairs of ions.

In spite of the fact that according to the legislation of the Russian Federation the majority of non-system units are forbidden to use, the x-ray is used in the marking of dosimeters. But they will soon cease to be used, because it was more practical to write down and calculate everything in the sins and sievers.

Glad

The radiation unit rad is outside the SI system and is equal to the amount of radiation in which one millionth of the energy is transferred to one gram of matter. That is, one happy is 0.01 joule per kilogram of matter.

The material that absorbs energy can be both living tissue and other organic and inorganic substances and substances: soil, water, air. As an independent unit was glad to be introduced in 1953 and in Russia has the right to be used in physics and medicine.

Gray

This is another unit for measuring the level of radiation, which is recognized by the International System of Units. It reflects the absorbed dose of radiation. It is believed that the substance received a dose of one gray if the energy that was transmitted with radiation is equal to one joule per kilogram.

This unit received its name in honor of the English scientist Lewis Gray and was officially introduced into science in 1975. According to the rules, the full name of the unit is written with a small letter, but its abbreviated designation is from a large one. One gray is equal to a hundred rads. In addition to simple units, science uses multiple and their equivalent equivalents, such as kilohera, megacre, decigra, centigray, microgrey and others.

Sievert

The unit of measurement of radiation sievert is used to denote effective and equivalent radiation doses and also enters the SI system, like gray and becquerel. Used in science since 1978. One sievert is equal to the energy absorbed by a kilogram of tissue after exposure to one warming gamma-ray. The name of the unit was given in honor of Rolf Sievert, a scholar from Sweden.

Judging by definition, sieverts and gray are equal, that is, equivalent and absorbed doses are the same size. But there is a difference between them. In determining the equivalent dose, it is necessary to take into account not only the quantity, but also other radiation properties, such as the wavelength, amplitude and what particles it represents. Therefore, the numerical value of the absorbed dose is multiplied by the radiation quality factor.

So, for example, for all other equal conditions, the absorbed alpha-particle effect will be twenty times stronger than the same dose of gamma radiation. In addition, it is necessary to take into account the tissue coefficient, which shows how the organs react to radiation. Therefore, an equivalent dose is used in radiobiology, and effective - in occupational health (to normalize the effects of radiation).

Solar constant

There is a theory that life on our planet came about thanks to solar radiation. Units of measurement of radiation from the star are calories and watts, divided by the unit of time. So it was decided because the amount of radiation from the Sun is determined by the amount of heat that the objects receive, and the intensity with which it comes. Only half a millionth of the total amount of energy released reaches the Earth.

Radiation from stars spreads in space at the speed of light and into our atmosphere will get in the form of rays. The spectrum of this radiation is quite wide - from "white noise", that is, radio waves, to X-rays. Particles that also get together with radiation are protons, but sometimes there can be electrons (if the energy release was large).

The radiation received from the Sun is the driving force of all living processes on the planet. The amount of energy we receive depends on the time of year, the position of the star above the horizon and the transparency of the atmosphere.

The effect of radiation on living things

If the living tissues of the same characteristics are irradiated by different types of radiation (in the same dose and intensity), the results will vary. Therefore, to determine the effects, only the absorbed or exposure dose is small, as in the case of nonliving objects. On the stage, units of measurement of penetrating radiation appear, such as sieverts of beers and gray, which indicate an equivalent dose of radiation.

Equivalent is the dose absorbed by the living tissue and multiplied by the conditional (tabulated) coefficient, which takes into account how dangerous this or that type of radiation is. Most often, a sievert is used to measure it. One sievert equals one hundred beers. The higher the coefficient of themes, respectively, the radiation is more dangerous. So, for photons this is a unit, and for neutrons and alpha particles - twenty.

Since the Chernobyl accident in Russia and other CIS countries, special attention has been paid to the level of radiation exposure to humans. The equivalent dose from natural radiation sources should not be more than five millisieverts per year.

The effect of radionuclides on non-living objects

Radioactive particles carry a charge of energy, which they transmit to the substance when they collide with it. And the more particles come in contact with a certain amount of matter on their way, the more energy they will get. The amount is estimated in doses.

1. The absorbed dose is the amount of radioactive radiation that was received by a unit of matter. It is measured in greeks. This value does not take into account the fact that the effect of different types of radiation on matter is different.
2. Exposure dose - is an absorbed dose, but taking into account the degree of ionization of the substance from the effects of different radioactive particles. Measured in coulombs per kilogram or X-rays.