Надеина Л.В. Радиоэкология
Подождите немного. Документ загружается.
21
i.e – то есть
instead of – вместо чего-либо; взамен чего-л.
nevertheless – тем не менее; однако, все-таки
either …. or – или ….. или
in the same way – так же
because – потому что; так как
however – однако; тем не менее; несмотря на (э)то
for example – например
according to – в соответствии с; согласно; по
more broadly – значительно шире; более широко
thus – так; таким образом; итак; соответственно
in addition – к тому же; кроме того; сверх того
Radiation
Radiation is energy in motion. Not only does radiation come from ele-
ments in the form of radioactivity, some come from our natural environment,
others from human activities and vices.
22
Non-ionizing radiation: Non-ionizing radiation, by contrast, refers to
any type of radiation that does not carry enough energy per photon to ionize
atoms or molecules. Most especially, it refers to the lower energy forms of
electromagnetic radiation (i.e., radio waves, microwaves, terahertz
radiation, infrared light, and visible light). The effects of these forms of
radiation on living tissue have only recently been studied. Instead of
producing charged ions when passing through matter, the electromagnetic
radiation has sufficient energy only for excitation, the movement of an
electron to a higher energy state. Nevertheless, different biological effects
are observed for different types of non-ionizing radiation.
Neutron radiation: Neutron radiation is a kind of non-ionizing
radiation that consists of free neutrons. These neutrons may be emitted
during either spontaneous or induced nuclear fission, nuclear fusion
processes, or from other nuclear reactions. It does not ionize atoms in the
same way that charged particles such as protons and electrons do (exciting an
electron), because neutrons have no charge. However, neutron interactions
are largely ionizing, for example when neutron absorption results in gamma
emission and the gamma subsequently removes an electron from an atom, or
a nucleus recoiling from a neutron interaction is ionized and causes more
traditional subsequent ionization in other atoms.
Electromagnetic radiation: Electromagnetic radiation (sometimes
abbreviated EMR) takes the form of self-propagating waves in a vacuum or
in matter. EM radiation has an electric and magnetic field component which
oscillate in phase perpendicular to each other and to the direction of energy
propagation. Electromagnetic radiation is classified into types according to
the frequency of the wave, these types include (in order of increasing
frequency): radio waves, microwaves, terahertz radiation, infrared radiation,
visible light, ultraviolet radiation, X-rays and gamma rays. Of these, radio
waves have the longest wavelengths and Gamma rays have the shortest. A
small window of frequencies, called visible spectrum or light, is sensed by
the eye of various organisms, with variations of the limits of this narrow
spectrum. EM radiation carries energy and momentum, which may be
imparted when it interacts with matter. The electromagnetic spectrum is the
range of all possible electromagnetic radiation frequencies. The
electromagnetic spectrum of an object is the characteristic distribution of
electromagnetic radiation emitted by, or absorbed by, that particular object.
Light: Light, or visible light, is electromagnetic radiation of a
wavelength that is visible to the human eye (about 400–700 nm), or up to
23
380–750 nm. More broadly, physicists refer to light as electromagnetic
radiation of all wavelengths, whether visible or not.
Thermal radiation: Thermal radiation is the process by which the
surface of an object radiates its thermal energy in the form of electromagnetic
waves. Infrared radiation from a common household radiator or electric
heater is an example of thermal radiation, as is the light emitted by a glowing
incandescent light bulb. Thermal radiation is generated when heat from the
movement of charged particles within atoms is converted to electromagnetic
radiation. The emitted wave frequency of the thermal radiation is a
probability distribution depending only on temperature and for a genuine
black body is given by Planck’s law of radiation. Wien's law gives the most
likely frequency of the emitted radiation, and the Stefan–Boltzmann law
gives the heat intensity.
Black-body radiation: Black-body radiation is a common synonym for
thermal radiation (see above). It is so-called because the ideal radiator of
thermal energy would also be an ideal absorber of thermal energy: It would
not reflect any light, and thus would appear to be absolutely black.
In addition, people are exposed to radiation from man-made sources
such as color televisions, smoke detectors, computer monitors, and X-rays.
These sources account for less than one-fifth of our total radiation exposure.
There is no difference between natural radiation and its effects and man-
made radiation and its effects.
Cosmic radiation and air travel: Cosmic radiation is part of our natural
environment, and we are constantly exposed to a certain amount of ionizing
radiation. Radiation originating from outer space and the sun is called cosmic
radiation and contributes about 13% of the background radiation level on
Earth (a greater part is due to radon).
Cosmic radiation is a collection of many different types of radiation
from many different types of sources. When people speak simply of 'cosmic
radiation' they are usually referring specifically to the cosmic microwave
background radiation. This consists of very, very low energy photons (en-
ergy of about 2.78 Kelvin) whose spectrum is peaked in the microwave re-
gion and which are remnants from the time when the universe was only about
200,000 years old.
24
There are also very old remnant neutrinos in the cosmic radiation. Neu-
trinos pass through just about everything with no effect so they are harmless.
The photons are too low in energy to be dangerous.
On top of these there are higher energy particles that are being created con-
stantly by all luminous objects in the universe. Photons of all different ener-
gies/wavelengths are being created by our sun, other stars, quasi-stellar ob-
jects, black-hole accretion disks, gamma-ray bursts and so on. These ob-
jects also produce high-energy massive particles such as electrons, muons,
protons and anti-protons. These higher energy particles are potentially dan-
gerous, but most of these particles never make it to the earth. They are de-
flected by magnetic fields between us and the source, or they interact with
other particles, or they decay in flight.
The particles that do make it to the earth interact with our atmosphere,
which acts as a «radiation shield». The high-energy cosmic rays bombard us
all the time, but they interact quickly, producing particles of much lower en-
ergy which impact the earth harmlessly. If this was dangerous to us, we
wouldn't be here to discuss these things! Some particles, like neutrinos and
25
high energy muons, are passing through us all the time, but they interact so
weakly that they have no effect on our bodies. Of course, if we were in space
without the protection of our atmosphere then we would need some other
type of shielding from the radiation (spacesuits and protective covering on
our spacecrafts).
The radiation to worry about, of course, is the 'cosmic' radiation pro-
duced by our sun. There is only one type of cosmic radiation known to ad-
versely affect us and that's UV radiation from our sun, which causes skin
cancer in millions of people every year. Again, our atmosphere serves as a
shield, but ultraviolet photons do make it through – and without that protec-
tive ozone layer which blocks these photons we're all going to need a lot
more sunscreen!
Special features of cosmic radiation
: Cosmic radiation is a complex
mixture of charged and neutral particles, some of them generated when pri-
mary particles from space interact with the earth's atmosphere. This complex-
ity also leads to difficulties in measuring radiation doses from cosmic radia-
tion, but physicists have developed sophisticated approaches to deal with this
situation. For the human exposure situation one feature of cosmic radiation is
of particular importance: a large percentage of the effective radiation dose
from cosmic radiation is due to neutrons of different energy levels. Neutrons
are subatomic particles which - when compared to X-rays or Gamma rays -
cause more biological damage per dose unit.
Exposure during flying:
As a rule, cosmic radiation levels rise with in-
creasing altitude (up to about 20 km above ground). The actual radiation
level is influenced by a number of factors, most importantly through the
shielding provided by the earth's atmosphere. The overall effect for flight
crew and travelers is an increased radiation exposure during flights as com-
pared to staying on the ground. Flight crew passes up to 1000 hours per year
on board of flying planes, which leads to annual effective radiation doses in
the range of 2 to 5 milliSievert (mSv) for most crew. Occasional travelers ob-
tain a fraction of this value through less frequent leisure or occupational
flights. In comparison, the natural background radiation amounts to 2 to 3
mSv per year at most geographical locations worldwide.
(Merril Eisenbud, Thomas F.Gesell, Environmental radioactivity: from
natural, industrial, and military sources. Academic Press, 1997)
26
3.1 Give the English equivalents to the Russian words:
1. The effects of (этих форм радиации) on living tissue have only
recently been studied.
2. It does not ionize atoms in the same way that (заряженные частицы)
(такие как) protons and electrons do (exciting an electron), because neutrons
have no charge.
3. A small window of frequencies, called (видимый спектр) or light,
(улавливается) by the eye of various organisms, with variations of the limits
of this narrow spectrum.
4. Thermal radiation is generated when heat from the (движение заря-
женных частиц) within atoms (преобразовывается) to electromagnetic
radiation.
5. These sources account for (менее 1/5) of our total radiation exposure.
6. Neutrinos (проходят почти через все) with no effect so they are
harmless.
7. These higher energy particles are (потенциально опасны), but most
of these particles never make it to the earth.
8. The high-energy cosmic rays bombard us all the time, but they (бы-
стро взаимодействуют), producing particles of much lower energy which
impact the earth harmlessly.
9. The radiation (которая нас беспокоит), of course, is the 'cosmic' ra-
diation produced by our sun.
10. Again, our atmosphere serves (как щит), but ultraviolet photons do
make it through – and without that protective (озоновый слой) which blocks
these photons we're all going to need a lot more sunscreen.
11. This (сложность) also leads to (трудностям) in (измерении
доз
радиации) from cosmic radiation, but physicists have developed sophisti-
cated approaches to deal with this situation.
12. The actual radiation level is influenced by (ряд факторов), most
importantly through the shielding provided by (атмосфера Земли).
13. Cosmic radiation is a (сложная смесь заряженных и) neutral parti-
cles, some of them generated when primary particles from space interact with
the earth's atmosphere.
14. Of course, (если бы мы были в космосе) without the protection of
our atmosphere then we would need some other type of shielding from the
radiation (spacesuits and protective covering on our spacecrafts).
15. (Если бы это было опасно для нас), we wouldn't be here to discuss
these things!
27
16. (Существует только один известный тип космической
радиации) to adversely affect us and that's UV radiation from our sun, which
causes skin cancer in millions of people every year.
4. Read the text.
Isotopes
Isotopes are used in modern medicine for research purposes and diag-
nose diseases. In this picture a researcher is working with a radioactive iso-
tope in a laboratory. A number of precautions are required to protect the per-
son from too large a dose of the radioactive material.
Isotopes in Research and Medicine:
Scientists can now create radioactive forms of common elements, called
isotopes. Each isotope has a fixed rate of decay which can be characterized
by its half-life, or the length of time that it takes half of the radioactive atoms
in a sample to decay. Because each isotope decays at a unique and predict-
able rate, different isotopes can be used for a variety of purposes. For exam-
ple, isotopes play an important role in modern medicine. They can be in-
gested and traced in their path through the body, revealing biochemical and
metabolic processes with precision. These isotropic «tracers» are currently
used for practical diagnosis of disease as well as in research.
The dating of radioactive carbon has helped to define the history of life
on this planet. Any living organism takes in both radioactive and non-
radioactive carbon, either through the process of photosynthesis or by eating
plants or eating animals that have eaten plants. When the animal dies, how-
ever, uptake of carbon stops. As a result, radioactive carbon atoms are not re-
placed as they decay, and the amount of this material decreases over time.
28
The rate of decrease is predictable and can be described with accuracy, vastly
increasing our ability to date the biological events of our planet.
4.1 Memorize the following pairs of derivatives.
Noun Adjective
radioactivity radioactive
energy energetic
orbit orbital
atom atomic
nature natural
biology biological
difference different
tradition traditional
electricity electric
magnet magnetic
length long
vision visible
variety various
possibility possible
character characteristic
frequency frequent
danger dangerous
mass massive
protection protective
complexity complex
difficulty difficult
importance important
geography geographical
prediction predictable
practice practical
4.2 Choose between the alternatives to complete these sentences.
1. The electromagnetic spectrum of an object is the
characteristic/character distribution of electromagnetic radiation emitted
by, or absorbed by, that particular object.
29
2. For the human exposure situation one feature of cosmic radiation is of
particular important/importance: a large percentage of the effective radia-
tion dose from cosmic radiation is due to neutrons of different energy levels.
3. The photons are too low in energetic/energy to be dangerous.
4. Cosmic radiation is a collection of many difference/different types
of radiation from many different/difference types of sources.
5. Electromagnetic radiation is classified into types according to the
frequent/frequency of the wave, these types include: radio waves,
microwaves, terahertz radiation, infrared radiation, visible/vision light,
ultraviolet radiation, X-rays and gamma rays.
6. Ionizing radiation can consist of high speed subatomic particles
ejected from the nucleus or electromagnetic radiation (gamma-rays) emitted
by either the nucleus or orbital/orbit electrons.
7. Neutron interactions are largely ionizing, for example when neutron
absorption results in gamma emission and the gamma subsequently removes
an electron from an atomic/atom or a nucleus recoiling from a neutron
interaction is ionized and causes more traditional/tradition subsequent
ionization in other atoms.
8.
These objects also produce high-energy massive/mass particles such
as electrons, muons, protons and anti-protons.
9. These isotropic "tracers" are currently used for practical/practice di-
agnosis of disease as well as in research.
10. Not only does radiation come from elements in the form of radioac-
tive/radioactivity, some come from our natural environment, others from
human activities and vices.
5. Choose the right preposition to the following verbs. Some prepositions
can be used twice.
1. to consist a) with
2. to result b) from
3. to come c) on
4. to refer d) into
5. to pass e) to
6. to be classified f) through
7. to interact g) in
8. to depend h) of
9. to originate j) up
10. to deal
30
5.1 Put a preposition in each of the numbered spaces.
1. Most of the particles passed 1) _____ the foil undisturbed, suggesting
that the foil was made up mostly of empty space rather than of a sheet of sol-
id atoms.
2. Atomic particles, Rutherford's work showed, consisted 2) ___ empty
space surrounding a well-defined central core called a nucleus.
3. As they pass 3) _____ matter, they are scattered and absorbed and the
degree of penetration depends 4) ___ the kind of matter and the energy of the
rays.
4. A single interaction event between a primary x-ray photon and a par-
ticle of matter does not usually result 5) ____ the photon changing to some
other form of energy and effectively disappearing.
5. The event is also known as incoherent scattering because the photon
energy change resulting 6) _____ an interaction is not always orderly and
consistent.
6. The energy shift depends 7) ___ the angle of scattering and not on the
nature of the scattering medium.
7. Radioecology is a branch of ecology which studies how radioactive
substances interact 8) ____ nature, how different mechanisms affect the sub-
stances migration and uptake in food chain and ecosystems.
8. Fallout commonly refers 9) ____ the radioactive dust created when a
nuclear weapon explodes.
9. Radioecology is a science that came 10) ___ after the first tests of nu-
clear bombs.
10. The radiation sickness is generally used to refer 11) ___ acute prob-
lems caused by a large dosage of radiation in a short period, though this also
has occurred with long term exposure.
6. Read the text and do the task.
The Discovery of Radioactivity:
One hundred years ago, a group of scientists unknowingly ushered in
the Atomic Age. Driven by curiosity, these men and women explored the na-
ture and functioning of atoms. Their work initiated paths of research which
changed our understanding of the building blocks of matter; their discoveries
prepared the way for development of new methods and tools used to explore
our origins, the functioning of our bodies both in sickness and in health, and
much more.