Журавлева Сборник текстов для подготовки аспирантов-физиков 2011

tain kinds of agreements around enrichment and reprocessing," Moniz said.

Regardless, the U.S., at least, appears to be in no hurry to build nuclear reactors; only one is currently under construction at Watts Bar in Tennessee, with another potentially in the works at Vogtle in Georgia as a result of a loan guarantee from the Obama administration. The problem, as always, with nuclear is construction costs—the M.I.T. report assumes a nuclear reactor costs $4,000 per kilowatt of electricity produced to build—or $4 billion for a typical one-gigawatt nuclear power plant. Actual industry estimates for reactors being built today are at least $6 billion for such power plants and as much as $10 billion. "If you build a nuclear power plant and operate it well, it's going to produce a steady stream of income," Moniz noted. But "the disadvantage of nuclear is the enormous capital commitment that is made up front." Or as the report notes: "The track record for the construction costs of nuclear plants completed in the U.S. during the 1980s and early 1990s was poor. Actual costs were far higher than had been projected…. The first few U.S. plants will be a critical test for all parties involved."

Vocabulary

depleted - истощённый, обеднённый; исчерпанный (о запасах нефти или газа) ; выработанный (о расходуемых ресурсах или запасах)

affirm – подтверждать, утверждать, делать заявление

cask - бочка; бочонок; наливать в бочки; укладывать в бочки; хранить в бочках

ponder - обдумывать, взвешивать run out – кончаться

reprocessing = recycling – переработка, вторичное использование shortage - нехватка, недостаток; дефицит

constrain - заставлять, принуждать; обязывать to constrain Syn: compel , force, oblige; сдерживать, удерживать (от чего-л.)

complicate - затруднять, осложнять, усложнять abundant - обильный, богатый, изобилующий borehole - буровая скважина; шпур

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worrisome - беспокойный, испытывающий беспокойство, страдание, неприятность backbone - главная опора, основа; суть, сущность

proliferation - пролиферация, быстрое разрастание regardless - независимо

Find out and discuss modern problems nuclear power faces, which are mentioned in the text.

Find out the answers

What ways of solving these problems were mentioned? Why is keeping of depleted uranium complicated? What are the best ways of doing it?

What does the expression “leasing program” mean? What is the most reliable kind of nuclear reactor? What reactors do we use in our country?

Write down all words (in addition to vocabulary) connected with nuclear power.

Reproduce the text using this list of words.

Unit 3

Warming up activities

The Sun plays a significant role in every aspect of life in our planet. Remember the facts you know about the Sun. You’re going to read the article about this star. What surprising facts will you find out?

Does a Weaker Sun Mean a Warmer Earth?

Changes in the sun's output of various wavelengths of light have been warming the planet recently, contradicting scientists' computer models of the solar cycle

By David Bielo October 7, 2010

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SOLAR SURPRISE: In the most recent solar cycle, the sun put out more visible light than anticipated by scientists, exacerbating global warming.

The sun controls Earth's climate, bathing us in light ranging from ultraviolet to visible that warms the planet and drives the heat engines we know as weather systems and ocean currents. The sun is changeable, cycling from maximum to minimum outputs over a roughly 11-year cycle, increasing or decreasing the amount of light that reaches Earth as a result of the poorly understood aspects of the sun's seething nuclear fusion. Now new satellite measurements reveal that from 2004 to 2007—the declining phase of an unusually low and prolonged solar minimum—the sun put out even less ultraviolet light than expected but compensated by putting out more visible light. "The amount of visible radiation entering the lower atmosphere was increasing, which implies warming at the surface," says atmospheric physicist Joanna Haigh of Imperial College London, who led the research, published in Nature 0n October 7. "The solar radiative forcing of climate increased by 0.1 [watt per square meter]." That means the sun, at least for those three years, played a larger role in ongoing climate change than previously thought. Global climate change - average temperatures have risen by roughly 0.6 degree Celsius since the beginning of the 20th century - is caused by greenhouse gases in the atmosphere. These gases, chief among them carbon dioxide (CO2), act as a blanket, trapping the sun's heat that would otherwise be radiated back into space. Rising greenhouse gas levels in the atmosphere means rising average temperatures for the planet, causing climate change. But the change from 2004 to 2007 in the sun's output of visible light, and the attendant warming at Earth's surface of 0.1 watt per square meter, is roughly equivalent to the overall forcing of the sun on the climate over the past 25 years - estimated by the U.N. Intergovernmental Panel on Climate Change to be an additional 0.12 watt per square meter. That suggests scientists may have overestimated the sun’s role on the climate change.

Regardless, the solar change is dwarfed by the impact from the extra heat trapped by CO2 alone since 1750: an additional 1.66 watts per square meter, an effect that other greenhouse gases, such as methane, strengthen further. In other words, whereas the new satellite mea-

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surements call into question computer models of solar output, it does not change the fundamental physics of human-induced global warming Still, the finding suggests that scientists' understanding of solar cycles and their impact on climate needs more work. "The result reverses understanding of solar cycle climate effects," which had been that the sun generally warms the climate on the way up from minimum to maximum and generally cools the climate on the way down from maximum to minimum, explains atmospheric scientist Piers Forster of the University of Leeds in England. "But the opposite seems to have been true of the last solar cycle."

In addition, the larger than expected loss of UV light meant less stratospheric ozone up to 45 kilometers above the surface, but more above that line. That distinguishes this solar cycle from the preceding two and "suggests that the declining phase of solar cycle 23 is behaving differently to previous solar cycles," the team wrote.

Of course, solar irradiance measurements from just three years of one solar cycle cannot be applied to any other period than the one measured by the Spectral Irradiance Monitor on NASA's Solar Radiation and Climate Experiment (SORCE) satellite. "We cannot extrapolate to a 250-year period," Haigh says. "While this increase is similar to that produced by greenhouse gases, it may well turn round with the 11-year cycle so it can't be used to imply any long-term forcing."

In fact, the solar minimum for the last cycle was reached in 2009, and the sun’s activity has picked up in the intervening months. It remains to be seen if that will bring a decline in the sun's output of visible light - and therefore a decline in the sun's contribution to a warming climate during this upward part of the present solar cycle. The sun "was thought to be having a cooling effect over the last few years," Forster notes, a thought now shown likely to be mistaken. "Perhaps the sun has been trying to warm the Earth after all."

Vocabulary

anticipate [] 1) ожидать, предвидеть; предчувствовать, предвкушать,

exacerbate [] 1) а) обострять, осложнять, углублять, усиливать (кризис, недовольство)

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seethe [] 1. 1) бурлить, кипеть

attendant сопровождающий, сопутствующий

dwarfed отставший в росте; искусственно задержанный в росте intervening [] промежуточный, переходный, неустановившийся

Syn: intermediate , in-between , intermediary , interim , mediate , transitional

Explain the following statements

It is very important for humanity to know about the Sun as much as possible.

The extra heat trapped by CO2 hurts the Earth.

The received results reverse understanding of solar cycle climate effects

The larger than expected loss of UV light meant less stratospheric ozone up to 45

kilometers above the surface

Write down question you would like to ask to know more about the Sun.

Organise a briefing using these questions.

Unit 4

Warming up activities

Have you heard about nanotechnologies? What advantages do they have? What drawbacks of silicon technology do scientists try to overcome? This article considers a new method of cutting graphene, what is the main difference with the old one?

Graphite Novel: Nobel Prize Thrusts Graphene into the Spotlight - But Can It Deliver?

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Georgia Institute of Technology researchers have described a way of making graphene that preserves the material's conductive properties, an early step toward graphene silicon electronics

By Larry Greenmeier October 7, 2010

For years researchers have held out hope that graphene would be the material to pick up the mantle in the electronics industry when silicon hits its limits as the material of choice for making devices smaller, faster and cheaper. Yet, turning graphene's promise into a reality has been difficult to say the least, in part because of the inherent difficulty of working with a substance one atom thick.

Methods of cutting graphene into useable pieces tend to leave frayed edges that mitigate the material's effectiveness as a conductor. Now, a team of researchers at Georgia Institute of Technology led by Walter de Heer claims to have made a significant advance in that area by developing a technique for creating nanometer-scale graphene ribbons without rough edges. (A nanometer is one billionth of a meter.) Graphene has, of course, made headlines throughout the scientific world this week, thanks to the awarding of the Nobel Prise in Physics to two researchers at the University of Manchester in England who in 2004 pioneered a way of isolating graphen by repeatedly cleaving graphite with adhesive tape. The Nobel Prize committee recognized Andre Geim and Konstantin Novoselov "for groundbreaking experiments regarding the two-dimensional material graphene." Unlike the approach taken by Geim and Novoselov, de Heer and his team in the past have created graphene sheets by heating a silicon carbide surface to 1,500 degrees Celsius until a layer of graphene formed. The graphene was then cut to a particular size and shape using an electron beam. "This was a serious problem because cutting graphene leaves rough edges that destroy a lot of graphene's good properties, making it less conductive," says de Heer, regents' professor in Georgia Tech's School of Physics.

De Heer's new approach, described October 3 in Nature Nanotechnology, is to etch patterns into the silicon carbide and then heat that surface until graphene forms within the etched patterns. (Scientific Ameri-

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can is part of Nature Publishing Group.) In this way graphene forms in specific shapes and sizes without the need for cutting. "The whole philosophy has changed," he says. "We're not starting with an infinite sheet of graphene; we're growing it where we want to grow it." The researchers claim to have used the technique to fabricate a densely packed array of 10,000 top-gated graphene transistors on a 0.24-square- centimeter chip, a step toward their ultimate goal of creating graphene components that can be integrated with silicon for new generations of electronics. Such a consolidation would be a key milestone towards making microprocessors able to operate at terahertz speeds, 1,000 times faster than today's chips (whose speeds are clocked at billions of hertz). Another goal is to reduce heat generation as an increasing number of transistors are packed onto each chip. Such advances would continue to validate Moore’s law even as silicon circuits reach their miniaturization limit. "In principle, graphene can overcome silicon's limitation," de Heer says. "If we completely succeed [only] time will tell." Graphene and silicon will be able to coexist much the same way that airplanes and freight ships are used for transporting cargo. "They move at different speeds, but both are important because they have different costs," de Heer says. "I think a similar thing will happen in electronics."

De Heer is also quick to acknowledge that, although the study of graphene dates back to the 1970s, the field still has a long way to go. He and his team are now investigating how the ribbons they created will perform over time and to what degree their new approach improves on cutting pieces of graphene out of larger sheets. With so many open questions about graphene's viability, de Heer says he was surprised that the Nobel selection committee recognized graphene at this time. The technology has tremendous potential but only a fraction of that potential has been realized to date. "It's a little early," he says. "If you ask me the bottom line - What has graphene accomplished? - it's still trying to find its way."

Vocabulary

inherent - обязательно присущий, неотъемлемый thrust - пихать, толкать

frayed - изношенный, истёршийся; размочаленный

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mitigate - ослаблять; смягчать; подавлять

etch - гравировать; травить (на металле, стекле) ; вытравливать milestone - камень или столб с указанием миль; веха

validate - ратифицировать, утверждать Syn: ratify; объявлять действительным, придавать законную силу; обосновывать Syn: legalize; подтверждать

freight - фрахт; перевозка грузов (на зафрахтованном судне) cargo – груз

Answer the questions

In what way will proliferation of nanotechnologies serve the mankind?

What main drawback of silicon technology will be put away? Will both technologies be used by humanity, in what way? How will the speed change?

Using these questions as a plan retell the text

Unit 5

Warming up activity

Why do you think the black holes are widely discussed by scientists and by ordinary people?

Does your department deal with astrophysics?

What exact knowledge do scientists have about black holes? What theories about event horizon have you heard?

Artificial Event Horizon Emits Laboratory Analogue to Theoretical Black Hole Radiation

A laboratory experiment may have offered the first glimpses of a long-predicted quantum effect known as Hawking radiation

By John Matson October 1, 2010

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BLACK LIGHT: Black holes are believed to emit a faint glow of radiation due to quantum-mechanical effects. Although such radiation has never been observed, astronomers can identify black holes by the much more luminous radiation given off by matter falling into them. This image from the Chandra X-ray Observatory shows the region surrounding the Milky Way galaxy's central supermassive black hole.

Stephen Hawking is famous for many things: provocative bestselling books, Simpsons guest stints and his long and productive life with amyotrophic lateral sclerosis among them. In the field of astrophysics, the University of Cambridge physicist is also known for his work on gravity and black holes, includinghis 1974 postulation of the eponymous Hawking radiation , a phenomenon by which a black hole should give off a stream of particles from its outer boundary. Hawking radiation is predicted to arise from quantum fluctuations at the event horizon of a black hole, the point of no return beyond which even light is too slow to escape. Alongside light waves and regular matter falling into a black hole, Hawking realized, ought to be particles that pop into and out of existence. Quantum mechanics dictates that such short-lived particle pairs arise from even empty space, infusing the vacuum with its own ripples of activity. In most corners of the cosmos, those pairs quickly disappear together back into the vacuum, but at the edge of an event horizon one particle may be captured by the black hole, leaving the other free to escape as radiation.

The relatively faint emission has never been detected from a real black hole, so researchers have sought a number of laboratory proxies to demonstrate the general principles of the phenomenon. Now a group of Italian researchers reports what may be the first demonstration of a quantum-mechanical Hawking radiation analogue. In a paper set to be published in Physical Review Letters, the team reports observing photons trickling out from transient event horizons in a piece of glass. "We've given what we think are initial indications that Hawking radiation can be measured in the lab," says Daniele Facco, who led the research at the University of Insubria in Italy but is moving to the HeriotWatt University in Scotland. Faccio and his colleagues created the event horizons in a two-centimeter-long section of fused silica glass, a me-

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dium in which intense laser pulses can locally perturb the refractive index, or speed of light passing through the material.

As that perturbation travels through the glass, it forms a moving blockade for light trying to pass. "If you have a light pulse that's approaching the perturbation from behind, that is trying to catch up to it, it will feel an increase in refractive index that will slow it down," Faccio says. "Imagine yourself sitting on top of this perturbation, and you will see this light wave approaching you until it stops." In other words, the laser-induced perturbation acts as a boundary beyond which light cannot pass—a sort of moving event horizon. If a pair of photons is produced close enough to the event horizon, they will become separated and will be unable to return to the vacuum from whence they came. In a true black hole, the separation would be more pronounced; one of the particles would be lost for good to the black hole.

The researchers recorded photons streaking outward from the event horizon, about one photon per 100 laser pulses, with the traits predicted of Hawking radiation. The photon emission was unpolarized, for instance, and appeared in the right wavelengths. After taking steps to rule out possible contamination from more mundane mechanisms, such as fluorescence, the group concluded that the photons appeared to be spontaneously produced from the same physics underlying Hawking radiation.

Physicists in the field disagree about exactly what the observation means. Ulf Leonhardt of the University of St. Andrews in Scotland, whose group in 2008 proposed the optical method of producing the event horizons that Faccio and his colleagues used, says that the new research indeed represents the first observation of Hawking radiation. But others are not as certain. "I still need to be convinced that what they are seeing is the analogue of what Hawking found for black holes," says William Unruh, a physicist at the University of British Columbia who has demonstrated a classical, or nonquantum, analogue of Hawking radiation in the lab by studying the propagation of waves on moving water surface. One possible issue is that the Faccio group's photons emerge from the glass at a 90-degree angle from the direction of the laser pulse.

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