Учебное пособие Издание второе, переработанное и дополненное Москва Астрель act 2005
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| in | In measuring the current they used that device. Измеряя (при измерении) силу(ы) тока, они использовали этот прибор. |
| on, upon, after | On measuring the current they put down the results. Измерив (после измерения) силу(ы) тока, они записали результаты. |
| by | They achieved good results by experimenting. Они получили хорошие результаты путем экспериментирования (экспериментируя). |
| without | Не left the room without saying a word. Он ушел из комнаты, не сказав ни слова. |
• Phrases to be completed.
In solving the problem...
On comparing those phenomena...
In processing the data ...
Upon calculating the mass ...
By diluting the solution ...
Without increasing the speed ...
93
WORD AND PHRASE STUDY
• Study the meanings of due, be due to and due to.
due (to) adj. — соответствующий, надлежащий, вызванный,
обусловленный be due to — бытьобусловленным, являться следствием;
быть разработанным, предложенным due to prep. — благодаря, из-за, вследствии
(syn. because of, on account of, owing to, in view of, thanks to, by/in virtue of, consequent on)
• Now translate these sentences.
1,. Due consideration must be given to missile performance requirements.
No difference due to n-p scattering in the target was found.
Coincidences arise due to second-order effects.
A due explanation ofthe phenomenon of radioactivity was first given by the Curies.
This phenomenon was found to be due to the lowering of the temperature down to -200 °C.
An up-to-date apparatus, due to Frankenburg, isshown in Fig. 10.
READING (12A)
• Study the schematic representation of the passage given below, then read the passage and be prepared to summarize the problem using this diagram.
inactive (\Jm) T
critical size ( 10 cm)
I
chai
i
active (U235) i
fission —» neutrons
(carbon/graphite)
fissile —> materials
demonstration of scientific ideasefficiency production of
heavier isotopes I
FERMI-PILE AND PLUTONIUM
In the Fermi-pile, the fission chain reaction could be maintained in natural uranium, buTThe naturajuranium was so highly diluted by carbon thiaTRigh efficiency in energy production could not be achieved. Owing to the presence of inactive U238, the chain reaction in the pile could not possibly develop into an efficient explosion, nor could it be very useful as a power source.
So what good was the Fermi-pile, except for demonstrating the purely scientific principle of the possibility of a self-maintaining nuclear reaction? Of course, the demonstration of a purely scientific principle is always of very great importance, but the Fermi-pile was built at great expense in the midst of a perilous war when all expenditures were supposed to be judged on the basis of their military usefulness.
The Fermi-pile stood this acid test. Although the energy released in the fission of U235 nuclei could not be utilized and was literally sent down the drain by means of the water-cooling system, a new fissionable element was produced inside the pile during operation. The neutrons that were not used in the maintenance ofthe chain reaction in U235 nuclei were captured by U238 nuclei, producing the heavier isotope:
92U238 + on'->,2U23' + Y
Having an excess of neutrons, the nuclei of92U239 underwent two successive P- transformations, giving rise to elements with atomic numbers 93 and 94. These two elements, which do not exist in nature but have been produced artificially by human genius, were given the names neptunium andplutonium. The reactions following the neutron capture by U238 can be written:
A good tourist is supposed to be able to build a campfire even ifthe wood is soaking wet. This role of a good hiking tourist in the nuclear energy project was played by the Italian-American physicist, Enrico Fermi, who actually made the "wet" uranium logs "burn'VHe was able to do so by utilizing the fact mentioned above, that the effectiveness of fission neutrons in producing the fission of U235 nuclei increases quite considerably wjicjalhcy are slowed down. llsucfTilowingfTown of fission neutrons could be achieved, the presence of inactive U 238 would not make much difference.tTo slow down the original fission neutrons it was necessary to mix natural uranium with a large amountof carbon in theform of graphite. A large "pile" of graphite bricks with small pieces of natural uranium included in the structure was constructed in great secrecy under the grandstand ofthe University of Chicago Stadium, and on December 2, 1941, Professor A. Compton wired to Dr. Vannevar Bush in Washington, D.C.: "The Italian navigator has landed. The natives are friendly." In the secret language ofthe Manhattan Project this meant: "The Fermi-pile works successfully. Nuclear chain reaction is achieved."
92U»8^0,Np2-w + c-
Being chemically different from uranium, the plutonium produced in the Fermi-pile can be separated and purified with much less effort than it takes to separate a light uranium isotope from the heavy one, and this element turned out to be even more fissionable than U235. In fact, whereas U2'5 gives rise to 2.5 fission neutrons, the corresponding figure for Pu239 is 2.9 fission neutrons.
Critical Size
When a single fission process occurs inside a given sample of pure U235 or Pu239, several fission neutrons are ejected from the point where the nuclear breakup took place. The average distance a fission neutron must travel through the material in order to run into another nucleus is about 10 cm so that if the size ofthe sample in question is less than that, most of the fission neutrons will cross the surface of the sample and fly away before they have a chance to cause another fission and produce more neutrons. Thus, no progressive chain reaction can develop if the sample of fissionable material is too small. Going to larger and larger samples, we find that more fission neutrons produced in the interior have a chance to produce another fission by colliding with a nucleus before they escape through the surface, and for samples of a very large size only a small fraction of the neutrons produced in them has a chance to reach the surface before collidi ng with one of the nuclei. The size ofthe sample of a given fissionable material for which the percentage of neutrons giving rise to subsequent fission processes is high enough to secure a progressive reaction is known as the critical size for that particular material. Since the number of neutrons per fission is larger in the case of plutonium than in the case of uranium-235, the critical size of plutonium samples is smaller than that of uranium-235 samples because the former can afford larger losses of neutrons through its surface.
• Find English equivalents for the following Russian phrases.
не имело бы большого значения; зажечь костер, даже если дерево насквозь пропиталось водой; самоподдерживающаяся цепная реакция; выдержал суровое испытание; из-за наличия неактивного U23S; за исключением демонстрации чисто научного принципа; претерпели последовательные преобразования; приводя к образованию элементов; заставил гореть ценой огромных расходов; буквально была спущена в дренажную трубу; ценой гораздо меньших усилий, чем требуется для...; может позволить большие потери
• Read the passage carefully again and supply answers to the following questions.
What scientific discoveries led to the idea ofthe first chain reaction?
When and where was the first atomic pile constructed?
What fissile material was used in it?
What conditions should be met for the chain reaction to be achieved?
Could the Fermi-pile be useful as a power source? Why not?
What two scientific ideas did the Fermi-pile demonstrate?
Give a summary of the passage using the scheme on p. 94.
Choose the correct form to fit into each sentence.
(collisions, collide, colliding)
1. Quite frequently the two types of atom will.... The energy given up by the electron injumpingtoa lower state goes into creating an additional photon with the same characteristics as the ... photon. For samples of a very large size only a small fraction of the neutrons produced in them has a chance to reach the surface before... with one of the nuclei. There are two kinds of... between the electrons and the atoms.
(the question, in question, question)
2. The substance ... contains traces of this element. One might... these results. Ifthe size of the sample ... is less than 10 cm, most ofthe fission neutrons will cross the surface and flyaway.... arises of how accurately these data present the results obtained.
• Translate the following word combinations.
original fission neutrons, nuclear chain reaction, single fission process, vertical cloud chamber, cosmic ray particle, wide energy spread, total energy liberation, thick material layer, critical size level, nuclear power production, ordinary steam turbine
• Translate into Russian, observe the use of "theformer, the latter".
There are two different methods to count scintillations: in the former the microscope is used, in the latter, the Geiger-counter.
There are two ways to detect and measure radioactivity. The former is the gold-leaf electroscope, the latter, the Wilson cloud chamber.
Only two types of rays are deflected in the magnetic field: the former to the left, the latter to the right.
CLASSWORK
READING (12B)
• Skim the passage as fast as possible and find answers to the following questions.
What is the main problem in maintaininga steady chain reaction?
What are "control rods" used for?
What is the design of a "swimming pool" reactor?
For what purposes are nuclear power reactors used?
NUCLEAR REACTORS
A sample of fissionable material smaller than the "critical size" is unable to carry on a nuclear chain reaction. If the size of the sample is exactly critical, the number of neutrons produced in each generation is the same as that produced in the previous one, resulting in steady nuclear energy liberation. The original Fermi-pile and its later modifications maintain nuclear reactions at the critical size level. *It must be mentioned in this connection that the conditions of "criticality" are extremely unstable: a small deviation (отклонение) in one direction will result in the rapid extinction (уменьшение количества нейтронов) of fission neutrons and the cut-off of the nuclear chain reaction, whereas a deviation in another direction will lead to a rapid multiplication ofthe fission neutrons and the melting (плавление) of the entire structure. Thus, the important problem in maintaining a steady chain reaction is that of regulating the rate of neutron production and of keeping the chain reaction from "dying out" or "running away". *This is achieved by using "controlrods" made from neutron-absording materials (such as boron) which arc automatically pushed in or pulled out from narrow channels drilled through the reacting fissionable material as soon as the rate of neutron production drops below or exceeds the desired level.
We have already mentioned that Fermi-piles were unsuitable for purposes of nuclear power production because ofthe high dilution of uranium by carbon; they should be considered rather as "alchemicalplants" in which plutonium is produced. For the purpose of nuclear power production, we use the controlled nuclearehain reactions in pure fissionable materials, such as U235 or Pu234, which can be run at quite high temperatures. In the so-called "swimming pool" reactor (реактор бассейнового типа) in which several cylindrical containers filled with pure fissionable material arc placed at the bottom of a large water tank, the water circulating through the tank carries away the heat produced in the fission process and also protects the observer from the deadly nuclear radiation. The color of the water turns blue as a result of the so-called Cherenkoffs radiation produced in water by high-energy electrons.
Explain how you understand the italicized words and phrases in the text.
Give an adequate translation of the sentences marked with an asterisk.
Give a summary of the passage in English or in Russian.
Give a free translation of the text.
У каждого элемента есть радиоактивные изотопы, которые либо существуют в природе, либо возбуждаются искусственно бомбардировкой устойчивых ядер такими частицами, как протоны, альфа-частицы или нейтроны. Частица, однако, не будет поглощаться ядром мишени, если ее скорость не будет соответствовать (correspond with) одному из энергетических уровней (level) ядра. Тяжелые ядра, имеющие больше энергетических уровней, чем легкие, осуществляют захват частицы с большей вероятностью, и этот факт помогает объяснить значение урана, тория и других очень тяжелых атомов в ядерном исследовании.
Так как нейтрон не заряжен, на него не влияют заряженные электроны и протоны, и поэтому более вероятно, что он, а не другая частица, будет захвачен. В случае захвата нейтрона массовое число ядра увеличится и ядро станет неустойчивым и радиоактивным. По мере того как излучение продолжается, уровень радиоактивности уменьшается экспоненциально, и время, которое требуется для того, чтобы он достиг половины своей первоначальной (исходной) величины, известно как период полураспада изотопа (half-life).
HOMEWORK
(to be done in writing)
1. Translate into Russian.
The predicted accuracy was found to be difficult to obtain in practice.
Light was assumed to leave a source as an indefinite number of particles travelling in straight lines.
Collisions between electrons and neutral molecules in solids appear to be frequent.
The moon appears to be a particularly good gravitational antenna.
The new lasers were expected to work in principle at least at a very high efficiency in comparison with other lasers.
An intense beam of light is observed to emerge from the mirror ends of the crystal: the entire process is called light amplification by stimulated emission of radiation (hence the acronym "laser").
Solid-state lasers already exist and although they have not had the spectral purity of gas lasers, this situation seems to be changing.
At first the concept of charge density in an atom seems to bear little resemblance to Bohr's picture of an electron orbiting the nucleus, but the two views are closely related.
2. Translate into English.
Считают, что эти величины находятся в хорошем согласии с экспериментальными величинами.
По-видимому, высота остается одной и той же в течение всего периода времени.
Не наблюдалось, чтобы эти вещества обладали радиационными свойствами.
Оказывается, лазеры широко используются в медицине и в промышленности.
Маловероятно, чтобы он решил это уравнение.
Известно, что на движение электронов влияют эти столкновения.
Известно, что радиоактивность была случайно открыта в 1896году французским физиком Беккерелем.
UNIT THIRTEEN
GRAMMAR: GERUND
• Sentences to be translated.
The possibility of water being converted into ice is evident.
The teacher objected to our measuring this volume in advance.
There were other ways of applying high voltage.
The group couldn't help visiting the exhibition again.
The paper is worth(while) reading due to its importance.
The programmer worked very hard with the view to making the program intelligible.
Besides putting forward a new theory he succeeded in proving it experimentally.
Various methods of cooling transformers are used in practice.
WORD AND PHRASE STUDY
according to prep. (syn. in accord with, in accordance with) — согласно, в соответствии с
account/?. — описание, отчет; учет, принятие во внимание take into account (syn. take into consideration) — учитывать, принимать во внимание
give account of — объяснять, описать, охарактеризовать
take account of — учитывать
of no account — не имеющий значения
onaccountof — из-за, вследствие, на основании, по случаю
on no account — ни в коем случае
on this account — но этой причине, из-за, ввиду этого
to account for — объяснять, быть причиной, относить за счет
101
The earth's atmosphere exerts a pressure on account of its weight in the same way as liquids do.
Einstein's theory of light was put forward to account for the photoelectric effect.
The energy losses in a gaseous source arc to be taken into account.
This phenomenon is accounted for by the sudden rise of temperature.
Electromagnetic theory can give a satisfactory account ofthe transmission of light in transparent media.
No account was taken of relativistic electrons.
READING (13A)
• Read the passage carefully and explain the phenomenon of "phase change". Say why this phenomenon is of interest to physicists.
THE WORLD IS MADE OF SUBATOMIC PARTICLES
According to contemporary physicists, the world is made of several types of objects, collectively referred to as subatomic particles. (These particles can also be thought of as manifestations of something yet more fundamental, known as quantum fields.) There may be as many as I О89 identical copies of some of these particles in the present universe. The forms of matter familiar to us, both living and nonliving, on the earth and in the heavens, are all composed of various combinations of only three types of subatomic particles — protons, neutrons, and electrons. Dozens of other types of particles can be produced momentarily in the laboratory, however, and arc thought to have existed in large numbers in the early universe.
All subatomic particles are defined by a few qualities that they may possess, such as mass, spin, and electric charge. Two particles arc of the same type, if all of these qualities agree. Otherwise, they arc considered to be different particles. Particles of the same type are, as far as we know, truly identical in these properties of mass, spin, and charge rather than just very similar. If all photons, the particles that make up light, were not identical, lasers would not operate.
The subatomic particles readily convert into one another when they collide. The kinetic energy of motion of light particles can be converted into the energy associated with mass (rest energy) of heavy particles. In many cases, even isolated particles can convert spontaneously into others, if the latter are less massive. In all such transformations, only a few properties, such as the total electric charge, remain unchanged. The subatomic particles do not act like the changeless building blocks imagined by some Greek philosophers. In the last few years, physicists have realized that even those subatomic particles which exist have changed radically over the lifetime ofthe universe. It appears that evolution takes place on all levels of matter, not just on the more complex levels of living things. The driving force behind this evolution is the expansion ofthe universe, which by changing the environment in which particles are found, changes the particles themselves. Only twenty years ago, the idea that the properties of subatomic particles might depend on their environment would have been considered heresy. Nevertheless, there is now considerable theoretical support for this conclusion.
Under the conditions in which physicists usually observe subatomic particles, their defining properties are not perceived to vary, giving these properties an illusion of stability. However, under the immense temperatures and densities that prevailed in the early stages of the universe, the properties, such as mass, of some particles would have been very different from what they are now. This situation is related by nature to the variability of a liquid such as water. Under a fairly wide range of temperatures water remains liquid and its properties do not change much whatever the temperature within this range. But if the water is subjected to much lower temperatures, oris heated to above 100° Celsius, its properties change abruptly. The liquid becomes a solid (ice) ora gas (water vapour). This type of change, in which the properties of a substance change drastically as a result of a small variation in its environmental conditions, is called a "phase change" by physicists.
The presumed change in the properties of subatomic particles at very high temperatures is also considered to be a phase change, one that involves the properties of space, as well as ofthe particles in it. In other words, the particles do not react directly to a temperature change but to some alteration in space, (he medium, in which they find themselves.
It is easy to boil or freeze water, but very difficult to duplicate in the lab the extreme conditions present at the birth ofthe universe. Yet physicists have become convinced of the theory that atomic particles, and space itself, went through momentous phase changes during and after the Big Bang. The rapid cooling that followed that primordial explosion is thought to have generated several phase changes. After an incredibly short time (perhaps a microsecond), the subatomic stuff of the young universe became stabilized, combining into the particles that make up matter today.
• Look through the passage carefully and find English equivalents for the following Russian phrases.
известные под общим названием; действительно (истинно); идентичные, а не просто схожие; фазовые превращения; энергия покоя; рассматривалась бы как ересь; огромные температуры; невероятно короткий период; субатомный материал
• For each word in A find in В its equivalent having roughly the same meaning.
A. 1. abrupt; 2. immense; 3. rapid; 4. incredible; 5. drastic; 6. to prevail;
7. to presume; 8. to perceive
B. a) quick; b) unlimited, immeasurable; c) very powerful; d) improbable,
impossible to believe; e) sudden and surprising; 0 to understand (see or
notice); g) to be most common or general; h) to suppose to be true
without proof
• Fill in the blanks with information taken from the text.
The world is made up of 10s4... .
These subatomic particles have characteristic properties of..., and ....
These particles can be converted into one another while ....
Dozens of other types of particles can be produced only ....
Scientists believe that other types of particles existed ....
Under ordinary conditions subatomic particles are considered to be ... .
Under immense temperatures and densities ofthe Big Bang they might have undergone....
The Big Bang process might have lasted only ....
• Read the passage again and find answers to the following questions.
What do contemporary physicists know for certain about matter?
What do physicists assume concerning the other types of subatomic particles?
Why do physicists insist on the identity ofthe particles?
What should happen ifthe particles were not identical?
What phenomenon do the physicists call "phase change"?
What examples of phase changes could you give?
Could subatomic particles experience phase changes?
Under what conditions could they have experienced phase changes?
• Think and say a few words about:
Big Bang and subatomic world;
the matter makeup;
phase changes in everyday life and in subatomic world;
laboratory experimentation with subatomic particles.
CLASS WORK
READING (13B)
• The problem of the passage below is illustrated in a block-scheme. Look at it and say what you know about the problem. Then, read the passage and find the facts to prove or disprove your ideas.
The Universe
quarks/gluons
matter
photons/neutrinos
| > | field | ) |
| < | |
proton/neutron
PARTICLES AND FIELDS
The number of the particles of each type in the present universe is the result of a complicated history. Most ofthe particle types that were abundant in the early universe have long ago disappeared. We only observe them when they are produced briefly in laboratories, and then annihilate or decay. Because of this we are uncertain of how many particle types may exist.
In the present universe, quarks and electrons have properties that allow them to form the tightly bound clusters that we call nuclei and atoms. Photons and neutrinos cannot do this, and so exist much more diffusely throughout the universe.
Nevertheless, most of the universe we know is made of quarks and electrons, and the present picture we have of the world is largely an expression of the properties of these particles. Of the two, quarks have a greater tendency to cluster together. Indeed, this tendency is so pronounced that most physicists believe that quarks are never found in isolation, but only in combinations containing either three quarks or one quark and one antiquark. These are the combinations that make up most of the subatomic particles that we observe, such as protons and neutrons, the particles found in the nuclei of atoms.
The reasons why quarks insist on clustering in this way are not completely understood. There is a general theory, known as quantum chromodynamics (QCD) that attempts to describe how quarks behave. QCD involves the interactions of fields associated with quarks and fields associated with another type of particle called gluons (so named because they bind the quarks together). Most physicists believe that when the predictions of this theory are better understood, we will know why quarks cluster as they do.
Ever since the first microsecond after the origin of the universe, quarks have been bound together, in groups of three, into neutrons or protons. All of the other combinations of quarks or the other quark types, which also can bind together, are unstable under present conditions. That is, if they are produced, they change spontaneously into less massive particles, and eventually into some combination of the stable ones. Even neutrons are unstable when they are found in isolation — as when they arc produced in nuclear reactors — and decay into protons in a few minutes. The reason that neutrons exist at all in the present universe is that when given the chance they bind together into more complex and lasting objects. Neutrons can bind with protons into atomic nuclei, and with one another in immense numbers into neutron stars.
Electrons also bind with nuclei and with each other into the combinations that we know as atoms and molecules. This binding occurs through electric and magnetic forces, which are manifestations of the same quantum field whose particle aspect is the photon. The detailed properties of this field arc summarized in a theory known as quantum electrodynamics (QED), the most widely tested theory in quantum physics. No inaccuracies have been found in the theory, down to a level of error of less than one part in a billion.
Most physicists believe, on the basis of theoretical arguments, that even protons and bound neutrons are not really stable, and that over sufficiently long periods of time they decay into electrons or neutrinos. Such decays have not yet been observed, although experimental searches are underway. The time period over which this is thought to occur is 1031 years or more, so that few of the protons and neutrons produced in the early universe would have decayed yet in this way. However, by looking at matter containing thousands of tons of protons, a few proton decays should be seen in a year. According to this theory, ifthe universe continues to expand for another 1031 years or more, matter as we know it will have disappeared. The era in which the universe is dominated by the matter familiar to us will be very long by human and by galactic standards, but it may still be just an instant in the whole history ofthe universe.
• Look through the passage and find English equivalents for the following Russian phrases.
современная вселенная; во всей вселенной; сложная история; из-за этого; плотно связанные; выражение свойств; тенденция столь ярко выражена; зарождение (возникновение) вселенной; они спонтанно превращаются в...; через достаточно долгий период времени; экспериментальные исследования ведутся; всеголишь мгновение; стремятся сгруппироваться
• Fill in the blanks with information from the text or from any other source.
The matter of the universe is made up of....
The general theory describing the behaviour of quarks is....
The QCD involves the interaction of... and ....
Protons and neutrons arc made up of....
The subatorhic particles existing in the universe diffusely are ... and ... .
Neutrons can bind with one another into ....
QED involves the binding of... and ... into ....
The subatomic particles never found in isolation arc ....
• Choose the facts from the list below which you could consider as well-established by science. Give reasons for your choice.
The number of distinct particle types in nature.
Photonsand neutrinos cannot cluster.
Most matter of the universe is made up of quarks and electrons.
Electron is indivisible.
Quarks cannot be found in isolation.
Neutrons are unstable.
Protons are unstable.
Neutrons can bind with one another.
Quarks can bind with one another.
• Think and say a few words about:
distinct particle types known in nature;
the nature of quarks;
QCD and QED theories;
protons and neutrons, their present and future.
HOMEWORK
(to be done in writing)
1. Translate into Russian.
The Properties of Space
How is it possible for space to change, if space is conceived of as nothing at all? Actually, physicists no longer think of space in that way. Einstein, in his general theory of relativity, following up on the work ofthe nineteenth-century mathematicians Bernhard Riemann and William Clifford, asserted that the properties of any region of space depend considerably on the presence and form of matter nearby. For example, the space near the sun is distorted in its geometrical properties; it "curves" because ofthe star's great mass. A triangle drawn by intersecting light rays near the sun would not obey the rules of Euclidean geometry, its angles would not add up to 180 degrees. It is this distortion of space and a related change in the way time passes that earlier physicists identified as the force of gravity, and which in Einstein's theory leads to the motion of the planets in orbits around the sun.
2. Translate into English. Use the Gerund forms.
Стоит обсудить проблему субатомных частиц подробно.
Мы не можем не попытаться дать определение этим понятиям.
Не стоит повторять эти измерения без высокочувствительною прибора.
Нельзя не признать ценность этих исследований.
Не имеет смысла (не стоит) перечислять все достоинства этой работы.
Стоит учесть все недостатки этой работы.