English for students of physics. Часть 2 (110

7 Infrasound can’t be heard.

8 But that level is far above what exists in nature.

III.Answer the questions:

-What is the objective of the author's study?

-What are the main problems of measuring Infrasound?

-Explain the nature of a Schumann Resonance.

-According to the author, can infrasound be the solution to the mystery of the Maria Celesta and the Flying Dutchman?

-What solutions to the problem does he suggest?

-Who might be the recipient of this article?

IV. Style. Rephrase the passage of the article so that to make its language more formal and scientific.

V. Debate. Do you think it is a good idea to study paranormal activity from the point of view of physics, or should a physicist focus on something more scientific than that? Give your reasons.

Unit III. Using Sound Waves to Induce Nuclear Fusion with No External Neutron Source

I. Lead-in:

A.Work in pairs. Think of as many possible uses of sound waves as you can. Share your ideas with the group.

B.Can you think of any unusual ways of using sound waves in research and ordinary life? You can consult any sources you can for providing information.

A team of researchers from Rensselaer Polytechnic Institute, Purdue University, and the Russian Academy of Sciences has used sound waves to induce nuclear fusion without the need for an external A._______ source, according to a paper in the Jan. 27 issue of Physical Review Letters. The results address one of the most

prominent questions raised after publication of the team's earlier results in 2004,

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suggesting that "sonofusion" may be a B. _____ approach to producing neutrons for a variety of applications.

By bombarding a special mixture of acetone and benzene with oscillating sound waves, the researchers caused C. _____ in the mixture to expand and then violently collapse. This technique, which has been dubbed "sonofusion," produces a shock wave that has the potential to fuse D. ______ together, according to the team.

The telltale sign that fusion has occurred is the production of neutrons. Earlier experiments were criticized because the researchers used an external neutron source to produce the bubbles, and some have suggested that the neutrons detected as evidence of fusion might have been left over from this external source.

"To address the concern about the use of an external neutron source, we found a different way to E. ____ the experiment," says Richard T. Lahey Jr., the Edward E. Hood Professor of Engineering at Rensselaer and coauthor of the paper. "The main difference here is that we are not using an external neutron source to kick the whole thing off."

In the new setup, the researchers dissolved natural uranium in the solution, which produces bubbles through radioactive decay. "This completely obviates the need to use an external neutron source, resolving any lingering confusion associated with the possible influence of external neutrons," says Robert Block, professor emeritus of nuclear engineering at Rensselaer and also an author of the paper.

The experiment was specifically designed to address a fundamental research question, not to make a device that would be capable of producing energy, Block says. At this stage the new device uses much more energy than it releases, but it could prove to be an inexpensive and portable source of neutrons for sensing and imaging applications.

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To F. ______the presence of fusion, the researchers used three independent neutron detectors and one gamma ray detector. All four detectors produced the same results: a statistically significant increase in the amount of nuclear emissions due to sonofusion when compared to background levels.

As a G. _____, the experiments were repeated with the detectors at twice the original distance from the device, where the amount of neutrons decreased by a factor of about four. These results are in keeping with what would be predicted by the "inverse square law," which provides further evidence that fusion neutrons were in fact produced inside the device, according to the researchers.

The sonofusion debate began in 2002 when the team published a paper in Science indicating that they had detected neutron emissions from the implosion of cavitation bubbles of deuterated-acetone vapor. These data were questioned because it was suggested that the researchers used inadequate instrumentation, so the team replicated the experiment with an upgraded instrumentation system that allowed data acquisition over a much longer time. This led to a 2004 paper published in Physical Review E, which was subsequently criticized because the researchers still used an external neutron source to produce the bubbles, leading to the current paper in Physical Review Letters.

The latest experiment was conducted at Purdue University. At Rensselaer and in Russia, Lahey and Robert I. Nigmatulin performed the theoretical analysis of the bubble dynamics and predicted the shock-induced pressures, temperatures, and densities in the imploding bubbles. Block helped to design, set up, and calibrate a H.______ neutron and gamma ray detection system for the new experiments.

II. Fill in the gaps (A – H) with the words given: State-of-the-art, cross-check, verify, run, nuclei, viable, bubbles, neutron.

III.Understanding the text

1.Describe the process of sonofusion. In what way is it considered to be

special?

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2.What is supposed to show the result of the experiment?

3.Why was the experiment initially criticized? How did the scientists upgrade the process?

4.What is meant by a “fundamental research question”?

5.What do we understand by the “inverse square law”?

IV. Speaking

-Comment upon producing neutrons and the purpose of this process.

-Make a list of advantages of sonofusion by making some preliminary research in the Internet (Scientific forums can prove quite useful for that purpose).

-Make a list of points that contain criticism.

-Summarize the article in 5 – 7 sentences.

-Role-play a TV debate for a scientific programme about the research in the sphere of sonofusion.

Unit IV. Solar Cell Structure and Operation

I. Lead-in: In what way are the following words connected with solar cells: arrays, photovoltaic, solar panels, crystalline, space-based?

1. Solar cells, whether used in a central power station, a satellite, or a calculator, have the same basic structure. Light enters the device through an optical coating, or antireflection layer, that minimizes the loss of light by reflection; it effectively traps the light falling on the solar cell by promoting its transmission to the energy-conversion layers below. The antireflection layer is typically an oxide of silicon, tantalum, or titanium that is formed on the cell surface by spin-coating or a vacuum deposition technique.

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2. The three energy-conversion layers below the antireflection layer are the top junction layer, the absorber layer, which constitutes the core of the device, and the back junction layer. Two additional electrical contact layers are needed to carry the electric current out to an external load and back into the cell, thus completing an electric circuit. The electrical contact layer on the face of the cell where light enters is generally present in some grid pattern and is composed of a good conductor such as a metal. Since metal blocks light, the grid lines are as thin and widely spaced as is possible without impairing collection of the current produced by the cell. The back electrical contact layer has no such diametrically opposed restrictions. It need simply function as an electrical contact and thus covers the entire back surface of the cell structure. Because the back layer also must be a very good electrical conductor, it is always made of metal.

3.Since most of the energy in sunlight and artificial light is in the visible range of electromagnetic radiation, a solar cell absorber should be efficient in absorbing radiation at those wavelengths. Materials that strongly absorb visible radiation belong to a class of substances known as semiconductors. Semiconductors in thicknesses of about one-hundredth of a centimetre or less can absorb all incident visible light; since the junction-forming and contact layers are much thinner, the thickness of a solar cell is essentially that of the absorber. Examples of semiconductor materials employed in solar cells include silicon, gallium arsenide, indium phosphide, and copper indium selenide.

4.When light falls on a solar cell, electrons in the absorber layer are excited from a lower-energy “ground state,” in which they are bound to specific atoms in the solid, to a higher “excited state,” in which they can move through the solid. In the absence of the junction-forming layers, these “free” electrons are in random motion, and so there can be no oriented direct current. The addition of junctionforming layers, however, induces a built-in electric field that produces the photovoltaic effect. In effect, the electric field gives a collective motion to the

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electrons that flow past the electrical contact layers into an external circuit where they can do useful work.

5.The materials used for the two junction-forming layers must be dissimilar to the absorber in order to produce the built-in electric field and to carry the electric current. Hence, these may be different semiconductors (or the same semiconductor with different types of conduction), or they may be a metal and a semiconductor. The materials used to construct the various layers of solar cells are essentially the same as those used to produce the diode s and transistor s of solid-state electronics and microelectronics. Solar cells and microelectronic devices share the same basic technology. In solar cell fabrication, however, one seeks to construct a large-area device because the power produced is proportional to the illuminated area. In microelectronics the goal is, of course, to construct electronic components of ever smaller dimensions in order to increase their density and operating speed within semiconductor chips, or integrated circuits.

6.Since solar cells obviously cannot produce electric power in the dark, part of the energy they develop under light is stored, in many applications, for use when light is not available. One common means of storing this electrical energy is by charging electrochemical storage batteries. This sequence of converting the energy in light into the energy of excited electrons and then into stored chemical energy is strikingly similar to the process of photosynthesis.

II. Reading. Which paragraph speaks about the following? (Sometimes more than one answer is possible). Give your reasons.

A.The relation of power to the illuminated area.

B.The semiconductor materials employed in solar cells.

C.The structure of a solar cell.

D.The special properties of an absorber.

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E.The principle of operation of a solar cell.

F.The similarity of the process of converting energy to some natural phenomenon.

G.The materials used for making the constituent parts of a solar cell.

III. Speak about the functions of the following constituent components/ elements of a solar cell: the anti-reflection layer, the top/ back junction layers, the absorber layer; the grid lines, integrated circuits, storage batteries.

IV. Speaking

A.Get ready with the abstract of the article (5 – 6 lines).

B.Speak in detail about:

-the structure of a solar cell;

-the principle of its operation;

-the materials used for it.

C.In what way does the process of converting energy resemble the process of photosynthesis?

D. Supplementary Questions (this part can require some extra information)

Speak in more detail about:

1.The possible applications of solarls cells;

2.The advantages of using a solar panel;

3.The structure of a solar-panel;

4.The cost of materials and efficiency.

E. Discussion

Situation I. Advertise a solar panel. Draw out a list of its advantages. Try to sound convincing and scientific.

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Situation II. Try to convince the local authorities to let solar panels into the local market.

Unit V. Trapped Rainbow: New Technique To Slow Down, Stop And Capture Light Offers Bright Future For Internet, Powerful Computers

A.The negative index metamaterials that allow for unprecedented control over the flow of light have a sub-structure with tiny metallic components much smaller than the wavelength of the light and have recently been demonstrated experimentally for THz and infrared wavelengths. Covering the full rainbow colours in the visible frequency spectrum should be within science’s reach in the very near future.

B.The technique would allow the use of light rather than electrons to store memory in devices such as computers, enabling an increase in operating capacity of 1,000% by using light’s broad spectrum rather than single electrons. Slow light could also be used to increase the speed of optical networks, such as the Internet. At major interconnection points, where billions of optical data packets arrive simultaneously, it would be useful if we could control this traffic optically, by slowing some data packets to let others through. This system would work in the same way as traffic congestion calming schemes do on our motorways, when a reduction in the speed limit enables swifter overall flow of traffic.

C.Professor Ortwin Hess, his PhD student Kosmas Tsakmakidis of the Advanced Technology Institute and Department of Physics at the University of Surrey and Professor Alan Boardman from Salford University have revealed a technique which may be able to slow down, stop and capture light.

D.Professor Hess comments: Our “Trapped Rainbow” bridges the exciting fields of metamaterials with slow light research. It may open the way to the longawaited realization of an “optical capacitor”. Clearly, the macroscopic control

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and storage of photons will conceivably find applications in optical data processing and storage, a multitude of hybrid, photonic devices to be used in optical fibre communication networks and integrated photonic signal processors as well as become a key component in the realisation of quantum optical memories. It may further herald a new realm of photonics with direct application of the ‘Trapped Rainbow’ storage of light in a huge variety of scientific and consumer fields.

E.Previous attempts to slow and capture light have involved extremely low or cryogenic temperatures, have been extremely costly, and have only worked with one specific frequency of light at a time. The technique proposed by Professor Hess and Mr Kosmas Tsakmakidis involves the use of negative refractive index metamaterials along with the exploitation of the Goos Hänchen effect, which shows that when light hits an object or an interface between two media it does not immediately bounce back but seems to travel very slightly along that object, or in the case of metamaterials, travels very slightly backwards along the object.

F.Professor Hess’ theory shows that if you create a tapered layer of glass surrounded by two suitable layers of negative refractive index metamaterials a packet of white light injected into this prism from the wide end will be completely stopped at some point in the prism. As different component ‘colours’ of white light have different frequencies each individual frequency would therefore be stopped at a different stage down the taper, thereby creating the ‘trapped rainbow’.

I Order the paragraphs. Explain your choice.

II Explain the terms and expressions in bold.

IIIAnswer the questions.

-How can the system increase the speed of the Internet?

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-Describe the technique proposed by Professor Hess. How can the rainbow be “trapped”?

-What prospects, according to Professor Hess, does slow light have?

Trapping a Rainbow: Researchers Slow Broadband Light Waves With

Nanoplasmonic Structures

ScienceDaily (Mar. 15, 2011) – A team of electrical engineers and chemists at Lehigh University have experimentally verified the "rainbow" A. ______ effect, demonstrating that plasmonic structures can slow down light waves over a broad range of wavelengths. The idea that a rainbow of broadband light could be slowed down or stopped using plasmonic structures has only recently been predicted in theoretical studies of B. ______. The Lehigh experiment employed focused ion beams to mill a series of increasingly deeper, nanosized C. ______

into a thin sheet of silver. By focusing light along this plasmonic structure, this series of grooves or nano-gratings slowed each wavelength of optical light, essentially capturing each individual color of the visible spectrum at different points along the grating. 1. ______.

While the notion of slowing light or trapping a rainbow sounds like ad speak, finding practical ways to control D. ____ -- the particles that makes up light -- could significantly improve the capacity of data storage systems and speed the processing of optical data.

The research required the ability to engineer a metallic surface to produce nanoscale periodic gratings with varying groove depths. This alters the optical properties of the nanopatterned metallic surface, called Surface Dispersion Engineering. The E. _____ surface light waves are then trapped along this plasmonic metallic surface with each wavelength trapped at a different groove depth, resulting in a trapped rainbow of light.

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