Types of radiation and their properties. What are the types of radiation

Introduction

Ionizing radiation, if we talk about it in general view, - it different kinds microparticles and physical fields capable of ionizing matter. Main types ionizing radiation is electromagnetic radiation (X-ray and gamma radiation), as well as streams of charged particles - alpha particles and beta particles that occur during a nuclear explosion. Defence from damaging factors is the basis civil defense country. Consider the main types of ionizing radiation.

Types of radiation

alpha radiation

Alpha radiation is a stream of positively charged particles formed by 2 protons and 2 neutrons. The particle is identical to the nucleus of the helium-4 atom (4He2+). It is formed during the alpha decay of nuclei. For the first time, alpha radiation was discovered by E. Rutherford. Studying radioactive elements, in particular, studying such radioactive elements as uranium, radium and actinium, E. Rutherford came to the conclusion that all radioactive elements emit alpha and beta rays. And, more importantly, the radioactivity of any radioactive element decreases after a certain specific period of time. The source of alpha radiation is radioactive elements. Unlike other types of ionizing radiation, alpha radiation is the most harmless. It is dangerous only when such a substance enters the body (inhalation, eating, drinking, rubbing, etc.), since the range of an alpha particle, for example, with an energy of 5 MeV, in air is 3.7 cm, and in biological tissue 0, 05 mm. The alpha radiation of a radionuclide that has entered the body causes truly nightmarish destruction, tk. the quality factor for alpha radiation with energies less than 10 MeV is 20 mm. and energy losses occur in a very thin layer of biological tissue. It practically burns him. When alpha particles are absorbed by living organisms, mutagenic (factors that cause mutation), carcinogenic (substances or a physical agent (radiation) that can cause the development of malignant neoplasms) and other negative effects can occur. Penetrating ability A. - and. small because held back by a piece of paper.

beta radiation

Beta particle (beta particle), a charged particle emitted as a result of beta decay. The stream of beta particles is called beta rays or beta radiation.

Negatively charged beta particles are electrons (b-), positively charged - positrons (b+).

The energies of beta particles are distributed continuously from zero to some maximum energy, depending on the decaying isotope; this maximum energy ranges from 2.5 keV (for rhenium-187) to tens of MeV (for short-lived nuclei far from the beta stability line).

Beta rays under the action of electric and magnetic fields deviate from a rectilinear direction. The speed of particles in beta rays is close to the speed of light.

Beta rays are able to ionize gases, cause chemical reactions, luminescence, act on photographic plates.

Significant doses of external beta radiation can cause radiation burns to the skin and lead to radiation sickness. Even more dangerous is internal exposure from beta-active radionuclides that have entered the body. Beta radiation has a significantly lower penetrating power than gamma radiation (however, an order of magnitude greater than alpha radiation). A layer of any substance with a surface density of about 1 g/cm2 (for example, a few millimeters of aluminum or several meters of air) almost completely absorbs beta particles with an energy of about 1 MeV.

Gamma radiation

Gamma radiation is a type of electromagnetic radiation with an extremely short wavelength -< 5Ч10-3 нм и вследствие этого ярко выраженными корпускулярными и слабо выраженными волновыми свойствами. Гамма-квантами являются фотоны высокой энергии. Обычно считается, что энергии квантов гамма-излучения превышают 105 эВ, хотя резкая граница между гамма- и рентгеновским излучением не определена. На шкале электромагнитных волн гамма-излучение граничит с рентгеновским излучением, занимая диапазон более высоких частот и энергий. В области 1-100 кэВ гамма-излучение и рентгеновское излучение различаются только по источнику: если квант излучается в ядерном переходе, то его принято относить к гамма-излучению, если при взаимодействиях электронов или при переходах в атомной электронной оболочке-то к рентгеновскому излучению. Очевидно, физически кванты электромагнитного излучения с одинаковой энергией не отличаются, поэтому такое разделение условно.

Gamma radiation is emitted during transitions between excited states of atomic nuclei (the energies of such gamma quanta range from ~ 1 keV to tens of MeV), during nuclear reactions (for example, during the annihilation of an electron and a positron, the decay of a neutral pion, etc.) , as well as during the deflection of energetic charged particles in magnetic and electric fields (see Synchrotron radiation).

Gamma rays, unlike b-rays and b-rays, are not deflected by electric and magnetic fields and are characterized by greater penetrating power at equal energies and other equal conditions. Gamma rays cause the ionization of the atoms of matter. The main processes that occur during the passage of gamma radiation through matter:

Photoelectric effect (gamma quantum is absorbed by the electron of the atomic shell, transferring all the energy to it and ionizing the atom).

Compton scattering (gamma-quantum is scattered by an electron, transferring to it part of its energy).

The birth of electron-positron pairs (in the field of the nucleus, a gamma quantum with an energy of at least 2mec2=1.022 MeV turns into an electron and a positron).

Photonuclear processes (at energies above several tens of MeV, a gamma quantum is able to knock out nucleons from the nucleus).

Gamma rays, like any other photons, can be polarized.

Irradiation with gamma rays, depending on the dose and duration, can cause chronic and acute radiation sickness. Stochastic effects of radiation include various types of cancer. At the same time, gamma radiation inhibits the growth of cancerous and other rapidly dividing cells. Gamma radiation is a mutagenic and teratogenic factor.

A layer of matter can serve as protection against gamma radiation. The effectiveness of protection (that is, the probability of absorption of a gamma-quantum when passing through it) increases with an increase in the thickness of the layer, the density of the substance and the content of heavy nuclei (lead, tungsten, depleted uranium, etc.) in it.

Previously, people, in order to explain what they do not understand, invented various fantastic things - myths, gods, religion, magical creatures. And although he still believes in these superstitions a large number of people, we now know that everything has an explanation. One of the most interesting, mysterious and amazing topics is radiation. What does it represent? What kinds of it exist? What is radiation in physics? How is it absorbed? Is it possible to protect yourself from radiation?

general information

So, allocate the following types radiation: wave motion of the medium, corpuscular and electromagnetic. Most attention will be paid to the latter. Regarding the wave motion of the medium, we can say that it arises as a result of the mechanical motion of a certain object, which causes a consistent rarefaction or compression of the medium. An example is infrasound or ultrasound. Corpuscular radiation is a stream of atomic particles such as electrons, positrons, protons, neutrons, alpha, which is accompanied by natural and artificial decay of nuclei. Let's talk about these two for now.

Influence

Consider solar radiation. This is a powerful healing and preventive factor. The totality of related physiological and bio chemical reactions that proceed with the participation of light, called photobiological processes. They take part in the synthesis of biologically important compounds, serve to obtain information and orientation in space (vision), and can also cause harmful effects, such as the appearance of harmful mutations, the destruction of vitamins, enzymes, proteins.

About electromagnetic radiation

In the future, the article will be devoted exclusively to him. What does radiation in physics do, how does it affect us? EMP is electromagnetic waves that are emitted by charged molecules, atoms, particles. As major sources antennas or other radiating systems may protrude. The wavelength of the radiation (oscillation frequency) together with the sources is of decisive importance. So, depending on these parameters, gamma, x-ray, optical radiation is emitted. The latter is divided into a number of other subspecies. So, it is infrared, ultraviolet, radio emission, and also light. The range is up to 10 -13 . Gamma radiation is generated by excited atomic nuclei. X-rays can be obtained by deceleration of accelerated electrons, as well as by their transition to non-free levels. Radio waves leave their mark while moving along the conductors of radiating systems (for example, antennas) of alternating electric currents.

About ultraviolet radiation

Biologically, UV rays are the most active. Upon contact with the skin, they can cause local changes in tissue and cellular proteins. In addition, the effect on skin receptors is fixed. It reflexively affects the whole organism. Since it is a non-specific stimulant of physiological functions, it has a beneficial effect on the body's immune system, as well as on mineral, protein, carbohydrate and fat metabolism. All this manifests itself in the form of a general health-improving, tonic and preventive action solar radiation. It should also be mentioned about individual specific properties that a certain range of waves has. Thus, the effect of radiation on a person at a length of 320 to 400 nanometers contributes to the erythema-tanning effect. In the range from 275 to 320 nm, weak bactericidal and antirachitic effects are recorded. But ultraviolet radiation from 180 to 275 nm damages biological tissue. Therefore, care must be taken. Long-term direct solar radiation, even in a safe spectrum, can lead to severe erythema with swelling of the skin and a significant deterioration in health. Up to an increase in the likelihood of developing skin cancer.

Reaction to sunlight

First of all, infrared radiation should be mentioned. It has a thermal effect on the body, which depends on the degree of absorption of rays by the skin. The word "burn" is used to characterize its influence. The visible spectrum affects the visual analyzer and the functional state of the central nervous system. And through the central nervous system and to all human systems and organs. It should be noted that we are influenced not only by the degree of illumination, but also by the color scheme. sunlight, that is, the entire spectrum of radiation. So, color perception depends on the wavelength and influences our emotional activity, as well as the functioning of various body systems.

Red excites the psyche, enhances emotions and gives a feeling of warmth. But it quickly tires, contributes to muscle tension, increased breathing and increased blood pressure. Orange color causes a feeling of well-being and fun, yellow uplifts and stimulates nervous system and vision. Green calms, is useful during insomnia, with overwork, increases the overall tone of the body. Purple has a relaxing effect on the psyche. Blue calms the nervous system and keeps the muscles in good shape.

small digression

Why, considering what radiation is in physics, we are talking more about EMP? The fact is that it is in most cases that they mean it when they turn to the topic. The same corpuscular radiation and wave motion of the medium is an order of magnitude smaller and less known. Very often, when they talk about the types of radiation, they mean only those into which EMP is divided, which is fundamentally wrong. After all, speaking about what radiation is in physics, attention should be paid to all aspects. But at the same time, the emphasis is on the most important points.

About radiation sources

We continue to consider electromagnetic radiation. We know that it is a wave that occurs when an electrical or magnetic field. This process is interpreted by modern physics from the point of view of the theory of corpuscular-wave dualism. So it is recognized that the minimum portion of EMR is a quantum. But along with this, it is believed that it also has frequency-wave properties, on which the main characteristics depend. To improve the possibilities of classifying sources, different emission spectra of EMP frequencies are distinguished. So this:

1. Hard radiation (ionized);
2. Optical (visible to the eye);
3. Thermal (it is also infrared);
4. Radio frequency.

Some of them have already been considered. Each emission spectrum has its own unique characteristics.

Nature of sources

Depending on their origin, electromagnetic waves can occur in two cases:

1. When there is a perturbation of artificial origin.
2. Registration of radiation coming from a natural source.

What can be said about the first? Artificial sources are most often a side effect that occurs as a result of the operation of various electrical appliances and mechanisms. Radiation of natural origin generates the Earth's magnetic field, electrical processes in the planet's atmosphere, nuclear fusion in the depths of the sun. The degree of intensity of the electromagnetic field depends on the power level of the source. Conventionally, the radiation that is recorded is divided into low-level and high-level. The first ones are:

1. Almost all devices equipped with a CRT display (such as a computer).
2. Various household appliances, ranging from climate systems to irons;
3. Engineering systems that provide electricity to various objects. Examples include power cables, sockets, electricity meters.

High-level electromagnetic radiation is possessed by:

1. Power lines.
2. All electric transport and its infrastructure.
3. Radio and television towers, as well as mobile and mobile communication stations.
4. Elevators and other lifting equipment where electromechanical power plants are used.
5. Devices for converting voltage in the network (waves coming from a distribution substation or transformer).

Separately allocate special equipment that is used in medicine and emits hard radiation. Examples include MRI, X-ray machines, and the like.

The influence of electromagnetic radiation on humans

In the course of numerous studies, scientists have come to the sad conclusion that long-term exposure to EMR contributes to a real explosion of diseases. At the same time, many violations occur in genetic level. Therefore, protection against electromagnetic radiation is relevant. This is due to the fact that EMR has a high level of biological activity. In this case, the result of the influence depends on:

1. The nature of the radiation.
2. Duration and intensity of influence.

Specific moments of influence

It all depends on the location. Absorption of radiation can be local or general. As an example of the second case, we can cite the effect that power lines have. As an example of local influence, one can cite electromagnetic waves that emit an electronic watch or mobile phone. The thermal effect should also be mentioned. Due to the vibration of the molecules, the field energy is converted into heat. Microwave emitters work according to this principle, which are used to heat various substances. It should be noted that when influencing a person, the thermal effect is always negative, and even harmful. It should be noted that we are constantly irradiated. At work, at home, moving around the city. Over time, the negative effect only intensifies. Therefore, protection from electromagnetic radiation is becoming more and more important.

How can you protect yourself?

Initially, you need to know what you have to deal with. This will help a special device for measuring radiation. It will allow you to assess the security situation. In production, absorbing screens are used for protection. But, alas, they are not designed for use at home. There are three guidelines to start with:

1. Stay at a safe distance from devices. For power lines, television and radio towers, this is at least 25 meters. With CRT monitors and TVs, thirty centimeters is enough. Electronic watches should be no closer than 5 cm. And radio and cell phones are not recommended to be brought closer than 2.5 centimeters. You can choose a place using a special device - a fluxmeter. The permissible dose of radiation fixed by it should not exceed 0.2 μT.
2. Try to reduce the time you have to irradiate.
3. Always turn off electrical appliances that are not in use. After all, even when inactive, they continue to emit EMP.

About the silent killer

And let's finish the article with an important, albeit rather poorly known topic in wide circles - radiation. Throughout his life, development and existence, a person was irradiated by a natural background. natural radiation can be conditionally divided into external and internal exposure. The first includes cosmic radiation, solar radiation, the influence earth's crust and air. Even Construction Materials, from which houses and structures are created, generate a certain background.

Radiation radiation has a significant penetrating power, so it is problematic to stop it. So, in order to completely isolate the rays, it is necessary to hide behind a wall of lead, 80 centimeters thick. Internal exposure occurs when natural radioactive substances enter the body along with food, air, and water. In the bowels of the earth you can find radon, thoron, uranium, thorium, rubidium, radium. All of them are absorbed by plants, they can be in water - and when eating food, they enter our body.

Ionizing radiation (hereinafter - IR) is radiation, the interaction of which with matter leads to the ionization of atoms and molecules, i.e. this interaction leads to the excitation of the atom and the detachment of individual electrons (negatively charged particles) from the atomic shells. As a result, deprived of one or more electrons, the atom turns into a positively charged ion - primary ionization occurs. AI includes electromagnetic radiation (gamma radiation) and flows of charged and neutral particles - corpuscular radiation (alpha radiation, beta radiation, and neutron radiation).

alpha radiation refers to corpuscular radiation. This is a stream of heavy positively charged a-particles (nuclei of helium atoms), resulting from the decay of atoms of heavy elements such as uranium, radium and thorium. Since the particles are heavy, the range of alpha particles in matter (that is, the path on which they produce ionization) turns out to be very short: hundredths of a millimeter in biological media, 2.5-8 cm in air. Thus, it is capable of retaining these particles plain sheet paper or outer dead skin layer.

However, substances that emit alpha particles are long-lived. As a result of ingestion of such substances into the body with food, air or through wounds, they are carried throughout the body by blood flow, deposited in organs responsible for metabolism and body protection (for example, the spleen or lymph nodes), thus causing internal exposure of the body . The danger of such internal exposure of the body is high, because. these alpha particles create very big number ions (up to several thousand pairs of ions per 1 micron path in tissues). Ionization, in turn, causes a number of features of those chemical reactions that occur in matter, in particular, in living tissue (formation of strong oxidants, free hydrogen and oxygen, etc.).

beta radiation(beta rays, or a stream of beta particles) also refers to the corpuscular type of radiation. This is a stream of electrons (β-radiation, or, more often, simply β-radiation) or positrons (β+-radiation) emitted during the radioactive beta decay of the nuclei of some atoms. Electrons or positrons are formed in the nucleus during the transformation of a neutron into a proton or a proton into a neutron, respectively.

Electrons are much smaller than alpha particles and can penetrate deep into the substance (body) by 10-15 centimeters (compare with hundredths of a millimeter for alpha particles). When passing through a substance, beta radiation interacts with the electrons and nuclei of its atoms, spending its energy on this and slowing down the movement until it stops completely. Thanks to these properties, it is sufficient to have an appropriate thickness of an organic glass screen for protection against beta radiation. The use of beta radiation in medicine for superficial, interstitial and intracavitary radiotherapy.

neutron radiation- another type of corpuscular type of radiation. Neutron radiation is a flux of neutrons ( elementary particles that do not have an electric charge). Neutrons do not have an ionizing effect, but a very significant ionizing effect occurs due to elastic and inelastic scattering on the nuclei of matter.

Substances irradiated by neutrons can acquire radioactive properties, that is, receive the so-called induced radioactivity. Neutron radiation is produced during the operation of elementary particle accelerators, in nuclear reactors, industrial and laboratory installations, during nuclear explosions, etc. Neutron radiation has the highest penetrating power. The best for protection against neutron radiation are hydrogen-containing materials.

Gamma radiation and X-rays are related to electromagnetic radiation.

The fundamental difference between these two types of radiation lies in the mechanism of their occurrence. X-ray radiation is of extra-nuclear origin, gamma radiation is a product of the decay of nuclei.

X-ray radiation, discovered in 1895 by the physicist Roentgen. This is an invisible radiation that can penetrate, albeit to varying degrees, into all substances. Represents electromagnetic radiation with a wavelength of the order from - from 10 -12 to 10 -7. The source of X-rays is an X-ray tube, some radionuclides (for example, beta emitters), accelerators and accumulators of electrons (synchrotron radiation).

The x-ray tube has two electrodes - cathode and anode (negative and positive electrodes respectively). When the cathode is heated, electron emission occurs (the phenomenon of electron emission by the surface solid body or liquid). The electrons emitted from the cathode are accelerated by the electric field and hit the anode surface, where they are abruptly decelerated, resulting in X-ray radiation. Like visible light, X-rays cause blackening of photographic film. This is one of its properties, the main thing for medicine is that it is a penetrating radiation and, accordingly, a patient can be illuminated with its help, and since. tissues of different density absorb X-rays in different ways - then we can diagnose many types of diseases of internal organs at a very early stage.

Gamma radiation is of intranuclear origin. It occurs during the decay of radioactive nuclei, the transition of nuclei from an excited state to the ground state, during the interaction of fast charged particles with matter, annihilation of electron-positron pairs, etc.

The high penetrating power of gamma radiation is due to the short wavelength. To attenuate the flow of gamma radiation, substances are used that differ significantly mass number(lead, tungsten, uranium, etc.) and all kinds of high-density compounds (various concretes with metal fillers).

Radioactive radiation (or ionizing) is the energy that is released by atoms in the form of particles or waves of an electromagnetic nature. Man is exposed to such influence both through natural and anthropogenic sources.

The useful properties of radiation have made it possible to successfully use it in industry, medicine, scientific experiments and research, agriculture and other areas. However, with the spread of the use of this phenomenon, a threat to human health has arisen. A small dose of radiation exposure can increase the risk of acquiring serious diseases.

The difference between radiation and radioactivity

Radiation, in a broad sense, means radiation, that is, the propagation of energy in the form of waves or particles. Radioactive radiation is divided into three types:

• alpha radiation - a stream of helium-4 nuclei;
• beta radiation - the flow of electrons;
• gamma radiation is a stream of high-energy photons.

The characterization of radioactive emissions is based on their energy, transmission properties and the type of emitted particles.

Alpha radiation, which is a stream of positively charged corpuscles, can be blocked by air or clothing. This species practically does not penetrate the skin, but when it enters the body, for example, through cuts, it is very dangerous and has a detrimental effect on internal organs.

Beta radiation has more energy - electrons move with high speed and their sizes are small. So this species radiation penetrates through thin clothing and skin deep into tissues. Shielding of beta radiation can be done with an aluminum sheet of a few millimeters or a thick wooden board.

Gamma radiation is a high-energy radiation of an electromagnetic nature, which has a strong penetrating power. To protect against it, you need to use a thick layer of concrete or a plate made of heavy metals such as platinum and lead.

The phenomenon of radioactivity was discovered in 1896. The discovery was made by the French physicist Becquerel. Radioactivity - the ability of objects, compounds, elements to emit ionizing study, that is, radiation. The cause of the phenomenon lies in the instability atomic nucleus, which releases energy when it decays. There are three types of radioactivity:

• natural - characteristic of heavy elements, the serial number of which is greater than 82;
• artificial - initiated specifically with the help of nuclear reactions;
• induced - characteristic of objects that themselves become a source of radiation if they are strongly irradiated.

Elements that are radioactive are called radionuclides. Each of them is characterized by:

• half-life;
• the type of radiation emitted;
• radiation energy;
• and other properties.

Sources of radiation

The human body is regularly exposed to radioactive radiation. Approximately 80% of the amount received annually comes from cosmic rays. Air, water and soil contain 60 radioactive elements that are sources of natural radiation. Main natural source radiation is considered inert gas radon released from the earth and rocks. Radionuclides also enter the human body with food. Some of the ionizing radiation to which humans are exposed comes from anthropogenic sources, ranging from nuclear power generators and nuclear reactors to radiation used for medical treatment and diagnosis. To date, common artificial sources of radiation are:

• medical equipment (the main anthropogenic source of radiation);
• radiochemical industry (mining, enrichment of nuclear fuel, processing of nuclear waste and their recovery);
• radionuclides used in agriculture, light industry;
• accidents at radiochemical plants, nuclear explosions, radiation emissions
• Construction Materials.

Radiation exposure according to the method of penetration into the body is divided into two types: internal and external. The latter is typical for radionuclides dispersed in the air (aerosol, dust). They get on the skin or clothes. In this case, the sources of radiation can be removed by washing them away. External irradiation causes burns of mucous membranes and skin. At internal type the radionuclide enters the bloodstream, for example by injection into a vein or through wounds, and is removed by excretion or therapy. Such radiation provokes malignant tumors.

The radioactive background significantly depends on geographical location- in some regions, the level of radiation can exceed the average by hundreds of times.

Effect of radiation on human health

Radioactive radiation due to the ionizing effect leads to the formation of free radicals in the human body - chemically active aggressive molecules that cause cell damage and death.

Cells of the gastrointestinal tract, reproductive and hematopoietic systems are especially sensitive to them. Radioactive exposure disrupts their work and causes nausea, vomiting, stool disorders, and fever. By acting on the tissues of the eye, it can lead to radiation cataracts. The consequences of ionizing radiation also include such damage as vascular sclerosis, impaired immunity, and a violation of the genetic apparatus.

The system of transmission of hereditary data has a fine organization. Free radicals and their derivatives can damage the structure of the carrier DNA genetic information. This leads to mutations that affect the health of future generations.

The nature of the impact of radioactive radiation on the body is determined by a number of factors:

• type of radiation;
• radiation intensity;
• individual characteristics of the body.

The results of radiation exposure may not appear immediately. Sometimes its effects become noticeable after a considerable period of time. At the same time, a large single dose of radiation is more dangerous than long-term exposure to small doses.

The absorbed amount of radiation is characterized by a value called Sievert (Sv).

• The normal radiation background does not exceed 0.2 mSv/h, which corresponds to 20 microroentgens per hour. When X-raying a tooth, a person receives 0.1 mSv.

• The lethal single dose is 6-7 Sv.

Application of ionizing radiation

Radioactive radiation is widely used in technology, medicine, science, military and nuclear industry and other fields. human activity. The phenomenon underlies such devices as smoke detectors, power generators, icing alarms, air ionizers.

In medicine, radioactive radiation is used in radiation therapy to treat cancer. Ionizing radiation allowed the creation of radiopharmaceuticals. They are used for diagnostic tests. On the basis of ionizing radiation, instruments for the analysis of the composition of compounds and sterilization are arranged.

The discovery of radioactive radiation was, without exaggeration, revolutionary - the use of this phenomenon brought mankind to new level development. However, it has also become a threat to the environment and human health. In this regard, maintaining radiation safety is important task modernity.

The term "radiation" comes from the Latin word "radius" and means a beam. In the broadest sense of the word, radiation covers all types of radiation that exist in nature - radio waves, infrared radiation, visible light, ultraviolet and, finally, ionizing radiation. All these types of radiation, having an electromagnetic nature, differ in wavelength, frequency and energy.

There are also radiations that are of a different nature and are streams of various particles, for example, alpha particles, beta particles, neutrons, etc.

Each time a barrier is placed in the path of radiation, it transfers some or all of its energy to that barrier. And the final effect of irradiation depends on how much energy was transferred and absorbed in the body. Everyone knows the pleasure of a bronze tan and the chagrin of the hardest sunburn. Obviously, overexposure to any kind of radiation is fraught with unpleasant consequences.

Most important for human health ionizing species radiation. Passing through the tissue, ionizing radiation transfers energy and ionizes atoms in molecules, which play an important biological role. Therefore, exposure to any type of ionizing radiation can affect health in one way or another. These include:

alpha radiation are heavy positively charged particles consisting of two protons and two neutrons tightly bound together. In nature, alpha particles are produced by the decay of atoms of heavy elements such as uranium, radium, and thorium. In the air, alpha radiation travels no more than five centimeters and, as a rule, is completely blocked by a sheet of paper or the outer dead layer of the skin. However, if a substance that emits alpha particles enters the body with food or inhaled air, it irradiates the internal organs and becomes potentially dangerous.

beta radiation are electrons that are much smaller than alpha particles and can penetrate several centimeters deep into the body. You can protect yourself from it with a thin sheet of metal, window glass and even ordinary clothing. Getting to unprotected areas of the body, beta radiation has an effect, as a rule, on the upper layers of the skin. During the accident at the Chernobyl nuclear power plant in 1986, firefighters suffered skin burns as a result of very strong exposure to beta particles. If a substance that emits beta particles enters the body, it will irradiate the internal tissues.

Gamma radiation are photons, i.e. electromagnetic wave that carries energy. In the air, it can travel long distances, gradually losing energy as a result of collisions with the atoms of the medium. Intense gamma radiation, if not protected from it, can damage not only the skin, but also internal tissues. Dense and heavy materials such as iron and lead are excellent barriers to gamma radiation.

x-ray radiation similar to gamma radiation emitted by nuclei, but produced artificially in an X-ray tube, which is not itself radioactive. Since the x-ray tube is powered by electricity, the x-ray emission can be turned on or off with a switch.

neutron radiation It is formed during the fission of the atomic nucleus and has a high penetrating power. Neutrons can be stopped by a thick concrete, water or paraffin barrier. Fortunately, in civilian life, nowhere, except in the immediate vicinity of nuclear reactors, neutron radiation practically does not exist.

In relation to X-ray and gamma radiation, definitions are often used "hard" and "soft". This is a relative characteristic of its energy and the penetrating power of radiation associated with it ("hard" - greater energy and penetrating power, "soft" - smaller). Ionizing radiation and their penetrating power

The number of neutrons in a nucleus determines whether a given nucleus is radioactive. In order for the nucleus to be in a stable state, the number of neutrons, as a rule, must be slightly higher than the number of protons. In a stable nucleus, protons and neutrons are so tightly bound together by nuclear forces that not a single particle can escape from it. Such a core will always remain in a balanced and calm state. However, the situation is quite different if the number of neutrons disturbs the equilibrium. In this case, the core has excess energy and simply cannot be kept intact. Sooner or later it will release its excess energy.

Various nuclei release their energy different ways: in the form of electromagnetic waves or particle streams. This energy is called radiation. radioactive decay

The process by which unstable atoms emit their excess energy is called radioactive decay, and such atoms themselves are radionuclides. Light nuclei with a small number of protons and neutrons become stable after one decay. When heavy nuclei, such as uranium, decay, the resulting nucleus is still unstable and, in turn, decays further, forming a new nucleus, and so on. The chain of nuclear transformations ends with the formation of a stable nucleus. Such chains can form radioactive families. The radioactive families of uranium and thorium are known in nature.

The concept of the decay intensity is given by the concept of the half-life - the period during which half of the unstable nuclei of a radioactive substance will decay. The half-life of each radionuclide is unique and unchangeable. One radionuclide, such as krypton-94, is produced in nuclear reactor and disintegrates very quickly. Its half-life is less than a second. Another, for example, potassium-40, was formed at the time of the birth of the Universe and is still preserved on the planet. Its half-life is measured in billions of years.