The flow of positively charged particles of helium nuclei radiation. Characteristics of individual types of radiation
Corpuscular radiation - ionizing radiation, consisting of particles with a mass other than zero.
alpha radiation - a stream of positively charged particles (nuclei of helium atoms - 24He), which moves at a speed of about 20,000 km / s. Alpha rays are formed during the radioactive decay of the nuclei of elements with large serial numbers and during nuclear reactions, transformations. Their energy fluctuates within 4-9 (2-11) MeV. The range of a-particles in matter depends on their energy and on the nature of the matter in which they move. On average, the range in air is 2-10 cm, in biological tissue - a few microns. Since a-particles are massive and have relatively high energy, their path in matter rectilinear , they cause a strongly pronounced ionization effect. Specific ionization is approximately 40,000 pairs of ions per 1 cm of run in air (up to 250,000 pairs of ions can be created over the entire length of the run). In a biological tissue, up to 40,000 pairs of ions are also created on a path of 1-2 microns. All energy is transferred to the cells of the body, causing him great harm.
Alpha particles are trapped by a sheet of paper and practically cannot penetrate the outer (outer) layer of the skin, they are absorbed by the stratum corneum of the skin. Therefore, a-radiation is not dangerous as long as radioactive substances emitting a-particles will not get inside the body through an open wound, with food or inhaled air - then they become extremely dangerous .
beta radiation - a stream of b-particles, consisting of electrons (negatively charged particles) and positrons (positively charged particles) emitted atomic nuclei during their b-decay. The mass of β-particles in absolute terms is 9.1x10-28 g. Beta-particles carry one elementary electric charge and propagate in the medium at a speed of 100 thousand km / s to 300 thousand km / s (ie, up to the speed of light) depending on the radiation energy. The energy of b-particles fluctuates within considerable limits. This is explained by the fact that during each b-decay of radioactive nuclei, the resulting energy is distributed between the daughter nucleus, b-particles and neutrinos in different ratios, and the energy of b-particles can vary from zero to some maximum value. The maximum energy ranges from 0.015-0.05 MeV (soft radiation) to 3-13.5 MeV (hard radiation).
Since b-particles have a charge, they deviate from the rectilinear direction under the influence of electric and magnetic fields. Possessing a very small mass, b-particles, when colliding with atoms and molecules, also easily deviate from their original direction (i.e., they are strongly scattered). Therefore, it is very difficult to determine the path length of beta particles - this path is too winding. Mileage
b-particles due to the fact that they have a different amount of energy is also subject to fluctuations. The length of the run in the air can reach
25 cm, and sometimes several meters. In biological tissues, the range of particles is up to 1 cm. The density of the medium also affects the path of the path.
The ionizing power of beta particles is much lower than that of alpha particles. The degree of ionization depends on the speed: less speed - more ionization. For 1 cm of the path in air, a b-particle forms
50-100 pairs of ions (1000-25 thousand pairs of ions all the way in the air). High-energy beta particles, flying past the nucleus too quickly, do not have time to cause the same strong ionizing effect as slow beta particles. When energy is lost, it is captured either by a positive ion to form a neutral atom, or by an atom to form a negative ion.
neutron radiation - radiation consisting of neutrons, i.e. neutral particles. Neutrons are produced in nuclear reactions (a chain reaction of nuclear fission of heavy radioactive elements, in reactions of synthesis of heavier elements from hydrogen nuclei). Neutron radiation is indirectly ionizable; the formation of ions occurs not under the action of the neutrons themselves, but under the action of secondary heavy charged particles and gamma quanta, to which the neutrons transfer their energy. Neutron radiation is extremely dangerous due to its high penetrating power (the range in air can reach several thousand meters). In addition, neutrons can cause induced (including in living organisms), turning atoms of stable elements into their radioactive ones. Hydrogen-containing materials (graphite, paraffin, water, etc.) are well protected from neutron irradiation.
Depending on the energy, the following neutrons are distinguished:
1. Ultrafast neutrons with an energy of 10-50 MeV. They are formed when nuclear explosions and operation of nuclear reactors.
2. Fast neutrons, their energy exceeds 100 keV.
3. Intermediate neutrons - their energy is from 100 keV to 1 keV.
4. Slow and thermal neutrons. The energy of slow neutrons does not exceed 1 keV. The energy of thermal neutrons reaches 0.025 eV.
Neutron radiation is used for neutron therapy in medicine, determination of the content of individual elements and their isotopes in biological media, etc. In medical radiology, mainly fast and thermal neutrons are used, mainly californium-252 is used, which decays with the release of neutrons with an average energy of 2.3 MeV.
electromagnetic radiation differ in their origin, energy, and also in wavelength. Electromagnetic radiation includes X-rays, gamma radiation from radioactive elements, and bremsstrahlung that occurs when strongly accelerated charged particles pass through matter. Visible light and radio waves are also electromagnetic radiation, but they do not ionize matter, because they are characterized by a large long wave (less rigidity). Energy electromagnetic field emitted not continuously, but in separate portions - quanta (photons). Therefore, electromagnetic radiation is a stream of quanta or photons.
X-ray radiation. X-rays were discovered by Wilhelm Conrad Roentgen in 1895. X-rays are quantum electromagnetic radiation with a wavelength of 0.001-10 nm. Radiation with a wavelength exceeding 0.2 nm is conditionally called "soft" X-ray radiation, and up to 0.2 nm - "hard". Wavelength - the distance over which radiation propagates in one period of oscillation. X-ray radiation, like any electromagnetic radiation, propagates at the speed of light - 300,000 km / s. The X-ray energy usually does not exceed 500 keV.
There are bremsstrahlung and characteristic X-rays. Bremsstrahlung occurs when fast electrons decelerate in the electrostatic field of the nucleus of atoms (ie, during the interaction of electrons with nuclei of atoms). When an electron of high energy passes near the nucleus, scattering (deceleration) of the electron is observed. The electron's speed decreases and part of its energy is emitted as a bremsstrahlung photon.
Characteristic X-rays occur when fast electrons penetrate deep into the atom and are knocked out of the internal levels (K, L and even M). The atom is excited and then returns to the ground state. In this case, electrons from the outer levels fill the vacated places in the inner levels and, in this case, photons of characteristic radiation are emitted with an energy equal difference energy of an atom in the excited and ground state (not exceeding 250 keV). Those. characteristic radiation arises when the electron shells of atoms are rearranged. During various transitions of atoms from an excited state to an unexcited state, excess energy can also be emitted in the form of visible light, infrared and ultraviolet rays. Because X-rays have a short wavelength and are less absorbed in a substance, they have a greater penetrating power.
Gamma radiation This is nuclear radiation. It is emitted by the nuclei of atoms during the alpha and beta decay of natural artificial radionuclides in those cases when an excess of energy is found in the daughter nucleus that is not captured by corpuscular radiation (alpha and beta particles). This excess of energy is instantly displayed in the form of gamma quanta. Those. gamma radiation is a stream of electromagnetic waves (quanta) that is emitted in the process radioactive decay when the energy state of the nuclei changes. In addition, gamma quanta are formed during the antihilation of a positron and an electron. In terms of properties, gamma radiation is close to X-rays, but has a greater speed and energy. The speed of propagation in vacuum is equal to the speed of light - 300,000 km/s. Since gamma rays have no charge, in electric and magnetic fields do not deviate, propagating in a straight line and uniformly in all directions from the source. The energy of gamma radiation ranges from tens of thousands to millions of electron volts (2-3 MeV), rarely reaches 5-6 MeV (so the average energy of gamma rays produced during the decay of cobalt-60 is 1.25 MeV). The composition of the gamma radiation flux includes quanta of various energies. During the decay of 131
The degree of protection depends on the energy of the penetrating radiation and the characteristics of the absorber. The thickness of the shield is equal to the mean free path of the particle. To study the passage of alpha particles in a substance, the following quantities are calculated:The empirical formula for calculating the average air mileage under normal conditions is:
4Mev< Е α < 7 МэВ
Average range of alpha particles in matter
(Bragg formula)
with a known atomic number of the absorbent substance
with a known range of alpha particles in air with the same energy
Beta particles are a stream of electrons and positrons. They have the same charge and mass. But the charge sign is different. In addition, the average lifetime of electrons is infinitely long, for positrons it is 10 -9 s. When they annihilate, they form two gamma rays: . Particles from artificial and natural radionuclides have an energy of 0 to 10 MeV. The energy distribution of beta particles is called the beta spectrum. The dependence of the number of beta particles after passing through a layer of matter depends on the energy of beta particles and the thickness of the absorber (3- at the minimum thickness of the absorber):
E β |
Radiation losses during braking |
Ionization loss |
Nuclear reactions |
(0,15<Е β <0,8 МэВ)
(0,8<Е β <3 МэВ)
(E β >0.5 MeV) (E β<0,5 МэВ)
If the thickness of the absorber is much less than the maximum range, then the attenuation of the flux density occurs according to the exponential law:
F (x) \u003d F about exp (-μx),
where x is the thickness of the absorber, ; μ-mass factor p
Change |
Sheet |
Document No. |
Signature |
the date |
Sheet |
3AES-6.12 PR-2 |
The number of particles that have passed through the absorber layer decreases with increasing absorber thickness x according to the law.
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Radiation and types of radioactive radiation, the composition of radioactive (ionizing) radiation and its main characteristics. The action of radiation on matter.
What is radiation
First, let's define what radiation is:
In the process of decay of a substance or its synthesis, the elements of the atom (protons, neutrons, electrons, photons) are ejected, otherwise we can say radiation occurs these elements. Such radiation is called ionizing radiation or what is more common radiation, or even easier radiation . Ionizing radiation also includes x-rays and gamma rays.
Radiation - this is the process of emission of charged elementary particles by matter, in the form of electrons, protons, neutrons, helium atoms or photons and muons. The type of radiation depends on which element is emitted.
Ionization- is the process of formation of positively or negatively charged ions or free electrons from neutrally charged atoms or molecules.
Radioactive (ionizing) radiation can be divided into several types, depending on the type of elements of which it consists. Different types of radiation are caused by different microparticles and therefore have different energy effects on matter, different ability to penetrate through it and, as a result, different biological effects of radiation.
Alpha, beta and neutron radiation- These are radiations consisting of various particles of atoms.
Gamma and X-rays is the emission of energy.
alpha radiation
- emitted: two protons and two neutrons
- penetrating power: low
- source exposure: up to 10 cm
- radiation speed: 20,000 km/s
- ionization: 30,000 pairs of ions per 1 cm of run
- high
Alpha (α) radiation arises from the decay of unstable isotopes elements.
alpha radiation- this is the radiation of heavy, positively charged alpha particles, which are the nuclei of helium atoms (two neutrons and two protons). Alpha particles are emitted during the decay of more complex nuclei, for example, during the decay of uranium, radium, and thorium atoms.
Alpha particles have a large mass and are emitted at a relatively low speed of 20,000 km/s on average, which is about 15 times less than the speed of light. Since alpha particles are very heavy, upon contact with a substance, the particles collide with the molecules of this substance, begin to interact with them, losing their energy, and therefore the penetrating power of these particles is not great and even a simple sheet of paper can hold them.
However, alpha particles carry a lot of energy and, when interacting with matter, cause its significant ionization. And in the cells of a living organism, in addition to ionization, alpha radiation destroys tissues, leading to various damage to living cells.
Of all types of radiation, alpha radiation has the least penetrating power, but the consequences of irradiating living tissues with this type of radiation are the most severe and significant compared to other types of radiation.
Exposure to radiation in the form of alpha radiation can occur when radioactive elements enter the body, for example, with air, water or food, as well as through cuts or wounds. Once in the body, these radioactive elements are carried by the bloodstream throughout the body, accumulate in tissues and organs, exerting a powerful energy effect on them. Since some types of radioactive isotopes that emit alpha radiation have a long lifespan, when they get inside the body, they can cause serious changes in cells and lead to tissue degeneration and mutations.
Radioactive isotopes are not actually excreted from the body on their own, therefore, once inside the body, they will irradiate the tissues from the inside for many years until they lead to serious changes. The human body is not able to neutralize, process, assimilate or utilize most of the radioactive isotopes that have entered the body.
neutron radiation
- emitted: neutrons
- penetrating power: high
- source exposure: kilometers
- radiation speed: 40,000 km/s
- ionization: from 3000 to 5000 pairs of ions per 1 cm of run
- biological effect of radiation: high
neutron radiation- This is man-made radiation that occurs in various nuclear reactors and during atomic explosions. Also, neutron radiation is emitted by stars in which active thermonuclear reactions take place.
Having no charge, neutron radiation, colliding with matter, weakly interacts with elements of atoms at the atomic level, therefore it has a high penetrating power. Neutron radiation can be stopped by using materials with a high hydrogen content, such as a container of water. Also, neutron radiation does not penetrate well through polyethylene.
Neutron radiation passing through biological tissues causes serious damage to cells, as it has a significant mass and a higher speed than alpha radiation.
beta radiation
- emitted: electrons or positrons
- penetrating power: average
- source exposure: up to 20 m
- radiation speed: 300,000 km/s
- ionization: from 40 to 150 pairs of ions per 1 cm of run
- biological effect of radiation: average
Beta (β) radiation arises during the transformation of one element into another, while the processes occur in the very nucleus of the atom of matter with a change in the properties of protons and neutrons.
With beta radiation, a neutron is converted into a proton or a proton into a neutron, with this transformation an electron or positron (an antiparticle of the electron) is emitted, depending on the type of transformation. The speed of the emitted elements approaches the speed of light and is approximately equal to 300,000 km/s. The emitted elements are called beta particles.
Having an initially high radiation speed and small dimensions of the emitted elements, beta radiation has a higher penetrating power than alpha radiation, but has hundreds of times less ability to ionize matter compared to alpha radiation.
Beta radiation easily penetrates through clothes and partially through living tissues, but when passing through denser structures of matter, for example, through metal, it begins to interact with it more intensively and loses most of its energy, transferring it to the elements of matter. A metal sheet of a few millimeters can completely stop beta radiation.
If alpha radiation is dangerous only in direct contact with a radioactive isotope, then beta radiation, depending on its intensity, can already cause significant harm to a living organism at a distance of several tens of meters from the source of radiation.
If a radioactive isotope emitting beta radiation gets inside a living organism, it accumulates in tissues and organs, exerting an energy effect on them, leading to changes in the structure of tissues and causing significant damage over time.
Some radioactive isotopes with beta radiation have a long decay period, that is, when they enter the body, they will irradiate it for years until they lead to tissue degeneration and, as a result, to cancer.
Gamma radiation
- emitted: energy in the form of photons
- penetrating power: high
- source exposure: up to hundreds of meters
- radiation speed: 300,000 km/s
- ionization:
- biological effect of radiation: low
Gamma (γ) radiation- this is an energetic electromagnetic radiation in the form of photons.
Gamma radiation accompanies the process of decay of atoms of matter and manifests itself in the form of radiated electromagnetic energy in the form of photons released when the energy state of the atomic nucleus changes. Gamma rays are emitted from the nucleus at the speed of light.
When a radioactive decay of an atom occurs, then others are formed from some substances. The atom of newly formed substances are in an energetically unstable (excited) state. By acting on each other, neutrons and protons in the nucleus come to a state where the forces of interaction are balanced, and excess energy is emitted by the atom in the form of gamma radiation
Gamma radiation has a high penetrating power and easily penetrates through clothes, living tissues, a little more difficult through dense structures of a substance such as metal. To stop gamma radiation would require a significant thickness of steel or concrete. But at the same time, gamma radiation has a hundred times weaker effect on matter than beta radiation and tens of thousands of times weaker than alpha radiation.
The main danger of gamma radiation is its ability to overcome considerable distances and affect living organisms several hundred meters from the source of gamma radiation.
x-ray radiation
- emitted: energy in the form of photons
- penetrating power: high
- source exposure: up to hundreds of meters
- radiation speed: 300,000 km/s
- ionization: from 3 to 5 pairs of ions per 1 cm of run
- biological effect of radiation: low
x-ray radiation- this is an energetic electromagnetic radiation in the form of photons, arising from the transition of an electron inside an atom from one orbit to another.
X-ray radiation is similar in action to gamma radiation, but has a lower penetrating power, because it has a longer wavelength.
Having considered various types of radioactive radiation, it is clear that the concept of radiation includes completely different types of radiation that have different effects on matter and living tissues, from direct bombardment by elementary particles (alpha, beta and neutron radiation) to energy effects in the form of gamma and X-rays. cure.
Each of the considered radiations is dangerous!
Comparative table with the characteristics of various types of radiation
characteristic | Type of radiation | ||||
alpha radiation | neutron radiation | beta radiation | Gamma radiation | x-ray radiation | |
radiated | two protons and two neutrons | neutrons | electrons or positrons | energy in the form of photons | energy in the form of photons |
penetrating power | low | high | average | high | high |
source exposure | up to 10 cm | kilometers | up to 20 m | hundreds of meters | hundreds of meters |
radiation speed | 20,000 km/s | 40,000 km/s | 300,000 km/s | 300,000 km/s | 300,000 km/s |
ionization, vapor per 1 cm of run | 30 000 | from 3000 to 5000 | from 40 to 150 | 3 to 5 | 3 to 5 |
biological effect of radiation | high | high | average | low | low |
As can be seen from the table, depending on the type of radiation, radiation at the same intensity, for example, at 0.1 Roentgen, will have a different destructive effect on the cells of a living organism. To take into account this difference, the coefficient k was introduced, which reflects the degree of exposure to radioactive radiation on living objects.
coefficient k | |
Type of radiation and energy range | Weight multiplier |
Photons all energies (gamma radiation) | 1 |
Electrons and muons all energies (beta radiation) | 1 |
neutrons with energy < 10 КэВ (нейтронное излучение) | 5 |
Neutrons from 10 to 100 keV (neutron radiation) | 10 |
Neutrons from 100 keV to 2 MeV (neutron radiation) | 20 |
Neutrons from 2 MeV to 20 MeV (neutron radiation) | 10 |
Neutrons> 20 MeV (neutron radiation) | 5 |
Protons with energies > 2 MeV (except for recoil protons) | 5 |
alpha particles, fission fragments and other heavy nuclei (alpha radiation) | 20 |
The higher the "coefficient k" the more dangerous the action of a certain type of radiation for the tissues of a living organism.
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The word "radiation" has Latin roots. Radius is Latin for ray. In general, radiation refers to all natural radiation. These are radio waves, ultraviolet, alpha radiation, even ordinary light. Some radiations are harmful, others can even become useful.
Education
The emergence of alpha particles is facilitated by nuclear alpha decay, nuclear reactions, or the complete ionization of helium-4 atoms. Primary cosmic rays are largely composed of alpha particles.
Basically, these are accelerated helium nuclei from interstellar gas flows. Some particles appear as chips from the heavier nuclei of cosmic rays. It is also possible to obtain them using a charged particle accelerator.
Characteristic
Alpha radiation is a type of ionizing radiation. This is a stream of heavy particles, positively charged, moving at a speed of about 20,000 km / s and having sufficient energy. The main sources of this type of radiation are radioactive isotopes of substances that have decay properties due to the weakness of atomic bonds. This decay contributes to the emission of alpha particles.
The main feature of this radiation is its very low penetrating power. In this it differs from other types of nuclear radiation. This follows from their highest ionizing abilities. But for each action of ionization, a certain energy is expended.
The interaction of heavy charged particles occurs more often with atomic electrons, so they almost do not deviate from the initial direction of motion. Based on this, the path of particles is measured as the direct distance from the source of the particles themselves to the point where they stop.
The measurement of the range of alpha particles is made in units of length or surface density of the material. In air, the magnitude of such a run can be 3 - 11 cm, and in liquid or solid media - only hundredths of a millimeter.
Human impact
Due to the very active ionization of atoms, alpha particles rapidly lose energy. Therefore, it is not enough even to penetrate the dead skin layer. This reduces the risks of radiation exposure to zero. But if the particles were produced using an accelerator, then they will become high-energy.
The main danger is borne by particles that appeared in the process of alpha decay of radionuclides. When they get inside the body, even a microscopic dose is enough to cause acute radiation sickness. And very often this disease ends in death.
Impact on electronic equipment
Alpha particles create electron-hole pairs in semiconductors. This can cause malfunctions in semiconductor devices. To prevent undesirable consequences for the production of microcircuits, materials with low alpha activity are used.
Detection
To find out if alpha radiation is present, and in what values, it is necessary to detect and measure it. For these purposes, there are detectors - particle counters. These devices register both the particles themselves and individual atomic nuclei, and determine their characteristics. The most famous detector is the Geiger counter.
Alpha particle protection
The low penetrating power of alpha radiation makes it quite safe. It affects the human body only in a special proximity to the source of radiation. A sheet of paper, rubber gloves, plastic glasses is enough to protect yourself.
The presence of a respirator should be a prerequisite. The main danger is the ingress of particles into the body, so the respiratory tract must be protected especially carefully.
Benefits of alpha radiation
The use of this type of radiation in medicine is called alpha therapy. It uses isotopes obtained with alpha radiation - radon, thoron, which have short lifespans.
Special procedures have also been developed that have a positive effect on the vital systems of the human body, and also have analgesic and anti-inflammatory effects. These are radon baths, alpha-radioactive compresses, inhalation of air saturated with radon. In this case, alpha radiation is useful radioactivity.
British doctors are successfully experimenting with new drugs that use the effects of alpha particles. The experiment was carried out on 992 patients whose prostate was affected by advanced stage cancer. The result was a 30% reduction in mortality.
The findings of scientists suggest that alpha particles are safe for patients. They are also more efficient than the commonly used beta particles. Also, their impact is more precise, and it takes no more than three hits to destroy a cancer cell. Beta particles achieve the same effect after several thousand hits.
Radiation sources
An actively developing civilization pollutes the environment actively. Uranium industry facilities, nuclear reactors, radiochemical industry enterprises, radioactive waste disposal facilities contribute to radioactive contamination of the space around us.
Also, alpha and other types of radiation are possible when using radionuclides at national economy facilities. Space research and networks of radioisotope laboratories also add radiation to their total mass.
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, a regular sheet of paper or an outer dead layer of skin is capable of retaining these particles.
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 the 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 a very large number of 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 surface, interstitial and intracavitary radiation therapy is based on the same properties.
neutron radiation- another type of corpuscular type of radiation. Neutron radiation is a stream 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 electron storage devices (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 of a solid 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 have a significant mass number (lead, tungsten, uranium, etc.) and all kinds of high-density compositions (various concretes with metal fillers).