Ionizing Radiation

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Ionizing radiation

Radiation hazard symbol.
Ionizing radiation has many practical uses, but it is also dangerous to human health. Both aspects are discussed below.
Ionizing radiation is either
particle radiation or electromagnetic radiation in which an individual particle/photon carries enough energy to ionize an atom or molecule by completely removing an electron from its orbit. If the individual particles do not carry this amount of energy, it is impossible for even a large flood of particles to cause ionization. These ionizations, if enough occur, can be very destructive to living tissue, and can cause DNA damage and mutations. Examples of particle radiation that are ionizing may be energetic electrons, neutrons, atomic ions or photons. Electromagnetic radiation can cause ionization if the energy per photon, or frequency, is high enough, and thus the wavelength is short enough. The amount of energy required varies between molecules being ionized. X-rays, and gamma rays will ionize almost any molecule or atom; Far ultraviolet, near ultraviolet and visible light are ionizing to some molecules; microwaves and radio waves are non-ionizing radiation.
However,
visible light is so common that molecules that are ionized by it will often react nearly spontaneously unless protected by materials that block the visible spectrum. Examples include photographic film and some molecules involved in photosynthesis
Types of radiation
Alpha radiation consists of
helium-4 nuclei and is readily stopped by a sheet of paper. Beta radiation, consisting of electrons, is halted by an aluminium plate. Gamma radiation is eventually absorbed as it penetrates a dense material.
Ionizing radiation is produced by
radioactive decay, nuclear fission and nuclear fusion, by extremely hot objects (the hot sun, e.g., produces ultraviolet), and by particle accelerators that may produce, e.g., fast electrons or protons or bremsstrahlung or synchrotron radiation.
In order for radiation to be ionizing, the particles must both have a high enough energy and interact with electrons. Photons interact strongly with charged particles, so photons of sufficiently high energy are ionizing. The energy at which this begins to happen is in the
ultraviolet region; sunburn is one of the effects of this ionization. Charged particles such as electrons, positrons, and alpha particles also interact strongly with electrons. Neutrons, on the other hand, do not interact strongly with electrons, and so they cannot directly ionize atoms. They can interact with atomic nuclei, depending on the nucleus and their velocity, these reactions happen with fast neutrons and slow neutrons, depending on the situation. Neutron radiation often produces radioactive nuclei, which produce ionizing radiation when they decay.
In the picture at left, gamma quanta are represented by wavy lines, charged particles and neutrons by straight lines. The little circles show where ionization processes occur.
An ionization event normally produces a positive atomic ion and an electron. High energy beta particles may produce
bremsstrahlung when passing through matter, or secondary electrons (δ-electrons); both can ionize in turn.
Gamma quanta do not ionize all along their path like alpha or beta particles (see
particle radiation. They interact by one of three effects: photoelectric effect, Compton effect, or pair production. By way of example, the figure shows Compton effect: two Compton scatterings that happen sequentially. In every scattering event, the gamma quantum transfers energy to an electron, and it continues on its path in a different direction with reduced energy.
In the figure, the neutron collides with a proton of the material which then becomes a fast recoil proton that ionizes in turn. At the end of its path, the neutron is captured by some nucleus in an (n,γ)-reaction that leads to a
neutron capture photon.
The negatively charged electrons and positively charged
ions created by ionizing radiation may cause damage in living tissue. If the dose is sufficient, the effect may be seen almost immediately, in the form of radiation poisoning. Lower doses may cause cancer or other long-term problems. The effect of the very low doses encountered in normal circumstances (from both natural and artificial sources, like cosmic rays, medical X-rays and nuclear power plants) is a subject of current debate. A 2005 report released by the National Research Council (the BEIR VII report, summarized in [1]) indicated that the overall cancer risk associated with background sources of radiation was relatively low.
Radioactive materials usually release
alpha particles which are the nuclei of helium, beta particles, which are quickly moving electrons or positrons, or gamma rays. Alpha and beta rays can often be shielded by a piece of paper or a sheet of aluminium, respectively. They cause most damage when they are emitted inside the human body. Gamma rays are less ionizing than either alpha or beta rays, but protection against them requires thicker shielding. They produce damage similar to that caused by X-rays such as burns, and cancer through mutations. Human biology resists germline mutation by either correcting the changes in the DNA or inducing apoptosis in the mutated cell.
Non-ionizing radiation is thought to be essentially harmless below the levels that cause heating. Ionizing radiation is dangerous in direct exposure, although the degree of danger is a subject of debate. Humans and animals can also be exposed to ionizing radiation internally: if radioactive isotopes are present in the environment, they may be taken into the body. For example, radioactive
iodine is treated as normal iodine by the body and used by the thyroid; its accumulation there often leads to thyroid cancer. Some radioactive elements also bioaccumulate.
[Reaction)
Ionizing radiation has many uses. An X-ray is ionizing radiation, and ionizing radiation can be used in medicine to kill cancerous cells. However, although ionizing radiation has many uses the overuse of it can be hazardous to human health. Shop assistants in shoe shops used to use an X-ray machine to check a child's shoe size, which would be a big treat for the child. But when it was discovered that ionizing radiation was dangerous these machines were promptly removed. Since they are able to penetrate matter, ionizing radiations are can be used by means of gamma or x-rays. This are usually used in industrial production. In biology, one uses mainly the fact that radiation sterilizes, and that it enhances mutations. For example, mutations may be induced by radiation to produce new or improved species. A very promising field is the sterile insect technique, where male insects are sterilized and liberated in the chosen field, so that they have no descendants, and the population is reduced.
Radiation is also useful in sterilizing medical hardware or food. The advantage for medical hardware is that the object may be sealed in plastic before sterilization. For food, there are strict regulations to prevent the occurrence of induced radioactivity. The growth of a seedling may be enhanced by radiation, but excessive radiation will hinder growth.
Electrons, x rays, gamma rays or atomic ions may be used in radiation therapy to treat malignant tumors (cancer).but it is very useful in helping those people who are suffering cancer.
.
[
Radiation hazard symbol.
Ionizing radiation has many practical uses, but it is also dangerous to human health. Both aspects are discussed below.
Ionizing radiation is either
particle radiation or electromagnetic radiation in which an individual particle/photon carries enough energy to ionize an atom or molecule by completely removing an electron from its orbit. If the individual particles do not carry this amount of energy, it is impossible for even a large flood of particles to cause ionization. These ionizations, if enough occur, can be very destructive to living tissue, and can cause DNA damage and mutations. Examples of particle radiation that are ionizing may be energetic electrons, neutrons, atomic ions or photons. Electromagnetic radiation can cause ionization if the energy per photon, or frequency, is high enough, and thus the wavelength is short enough. The amount of energy required varies between molecules being ionized. X-rays, and gamma rays will ionize almost any molecule or atom; Far ultraviolet, near ultraviolet and visible light are ionizing to some molecules; microwaves and radio waves are non-ionizing radiation.
However,
visible light is so common that molecules that are ionized by it will often react nearly spontaneously unless protected by materials that block the visible spectrum. Examples include photographic film and some molecules involved in photosynthesis
Types of radiation
Alpha radiation consists of
helium-4 nuclei and is readily stopped by a sheet of paper. Beta radiation, consisting of electrons, is halted by an aluminium plate. Gamma radiation is eventually absorbed as it penetrates a dense material.
Ionizing radiation is produced by
radioactive decay, nuclear fission and nuclear fusion, by extremely hot objects (the hot sun, e.g., produces ultraviolet), and by particle accelerators that may produce, e.g., fast electrons or protons or bremsstrahlung or synchrotron radiation.
In order for radiation to be ionizing, the particles must both have a high enough energy and interact with electrons. Photons interact strongly with charged particles, so photons of sufficiently high energy are ionizing. The energy at which this begins to happen is in the
ultraviolet region; sunburn is one of the effects of this ionization. Charged particles such as electrons, positrons, and alpha particles also interact strongly with electrons. Neutrons, on the other hand, do not interact strongly with electrons, and so they cannot directly ionize atoms. They can interact with atomic nuclei, depending on the nucleus and their velocity, these reactions happen with fast neutrons and slow neutrons, depending on the situation. Neutron radiation often produces radioactive nuclei, which produce ionizing radiation when they decay.
In the picture at left, gamma quanta are represented by wavy lines, charged particles and neutrons by straight lines. The little circles show where ionization processes occur.
An ionization event normally produces a positive atomic ion and an electron. High energy beta particles may produce
bremsstrahlung when passing through matter, or secondary electrons (δ-electrons); both can ionize in turn.
Gamma quanta do not ionize all along their path like alpha or beta particles (see
particle radiation. They interact by one of three effects: photoelectric effect, Compton effect, or pair production. By way of example, the figure shows Compton effect: two Compton scatterings that happen sequentially. In every scattering event, the gamma quantum transfers energy to an electron, and it continues on its path in a different direction with reduced energy.
In the figure, the neutron collides with a proton of the material which then becomes a fast recoil proton that ionizes in turn. At the end of its path, the neutron is captured by some nucleus in an (n,γ)-reaction that leads to a
neutron capture photon.
The negatively charged electrons and positively charged
ions created by ionizing radiation may cause damage in living tissue. If the dose is sufficient, the effect may be seen almost immediately, in the form of radiation poisoning. Lower doses may cause cancer or other long-term problems. The effect of the very low doses encountered in normal circumstances (from both natural and artificial sources, like cosmic rays, medical X-rays and nuclear power plants) is a subject of current debate. A 2005 report released by the National Research Council (the BEIR VII report, summarized in [1]) indicated that the overall cancer risk associated with background sources of radiation was relatively low.
Radioactive materials usually release
alpha particles which are the nuclei of helium, beta particles, which are quickly moving electrons or positrons, or gamma rays. Alpha and beta rays can often be shielded by a piece of paper or a sheet of aluminium, respectively. They cause most damage when they are emitted inside the human body. Gamma rays are less ionizing than either alpha or beta rays, but protection against them requires thicker shielding. They produce damage similar to that caused by X-rays such as burns, and cancer through mutations. Human biology resists germline mutation by either correcting the changes in the DNA or inducing apoptosis in the mutated cell.
Non-ionizing radiation is thought to be essentially harmless below the levels that cause heating. Ionizing radiation is dangerous in direct exposure, although the degree of danger is a subject of debate. Humans and animals can also be exposed to ionizing radiation internally: if radioactive isotopes are present in the environment, they may be taken into the body. For example, radioactive
iodine is treated as normal iodine by the body and used by the thyroid; its accumulation there often leads to thyroid cancer. Some radioactive elements also bioaccumulate.


[Reaction)
Ionizing radiation has many uses. An X-ray is ionizing radiation, and ionizing radiation can be used in medicine to kill cancerous cells. However, although ionizing radiation has many uses the overuse of it can be hazardous to human health. Shop assistants in shoe shops used to use an X-ray machine to check a child's shoe size, which would be a big treat for the child. But when it was discovered that ionizing radiation was dangerous these machines were promptly removed. Since they are able to penetrate matter, ionizing radiations are can be used by means of gamma or x-rays. This are usually used in industrial production. In biology, one uses mainly the fact that radiation sterilizes, and that it enhances mutations. For example, mutations may be induced by radiation to produce new or improved species. A very promising field is the sterile insect technique, where male insects are sterilized and liberated in the chosen field, so that they have no descendants, and the population is reduced.
Radiation is also useful in sterilizing medical hardware or food. The advantage for medical hardware is that the object may be sealed in plastic before sterilization. For food, there are strict regulations to prevent the occurrence of induced radioactivity. The growth of a seedling may be enhanced by radiation, but excessive radiation will hinder growth.
Electrons, x rays, gamma rays or atomic ions may be used in radiation therapy to treat malignant tumors (cancer).but it is very useful in helping those people who are suffering cancer.
.
[