Russia: we will hear how flying asteroids

29.04.2004

29.04.2004


—>


Russian receiver far-infrared detectors were sensitive "Hubble."

Scientists do not like the word "competition." The study, an experiment in extreme cases — a comparative study. But whatever you call what happened recently in the laboratory of the University of Rochester, the one where the ears of the American experience telescope "Hubble" is left feeling full and unconditional — "took our". Because the receiver is far-infrared detectors, developed by Moscow Institute of Physics, was much more sensitive "Hubble": where a quivering arrow that, our overload is through the roof, so we had to put additional filters

In general, the work performed by employees of the Moscow State University and their colleagues from the research center "pleased" with the support of Russian Federal Property Fund and the Foundation for Assistance MP NTS, makes a strong impression on the professionals, and easy on the brains of people with nelenivyh.

Start with the fact that the body temperature of 10 K for the authors of the project — not a "chilled to near absolute zero" and "heated" — even up to 10 K. Therefore emitting in the far infrared range. The radiation is very weak, and even catch it, especially against the background of a thermal radiation from the Sun and the Earth, it is very difficult. But it is very interesting — so you can learn many new things about what is happening in space. For example, to detect objects or phenomena in other ways subtle: from cold asteroids before fading stars. After all, in the ultraviolet, visible and near-infrared range, that is, where emit relatively warm and hot sources of radiation, "white spots" almost gone, because the methods and related equipment are many.

But the sensitive receivers operating in the field of electromagnetic radiation from 100 microns to 1 mm (this area is called terahertz), almost none. Some of the best are on the telescope "Hubble" — the pride of American astrophysicists. Housed on the satellite telescope — far away from the Earth as it is sent once and then to the thermal radiation of the planet do not clog air and get rid of the influence of the earth's atmosphere — has led to many discoveries. For example, to find "dark matter", which, as it turns out, is up to 90% of the mass of the universe.

But they would have been much more if the receiver sensitivity of its spectral measurement systems was higher. However, the capabilities of traditional receivers have been exhausted. A new, until recently, was not. Now they are, and developed them in the Physics Department of Moscow State University team of authors, led by Professor Dmitri Khokhlov.

Of course, the receiver material, its heart and ears simultaneously, authors create more than one year. But the first measurement by the receiver of a new type have been carried out recently. And they were very successful.

This detector works, in fact, as well as his brothers: a photon leads to the appearance of a free electron in the material, which must be registered. But the difficulty is that the electrons weak terahertz light can knock out a little, just one, and to register a single electron is not easy: it is usually quickly give up their freedom, dissipating the excess energy. Now, if the ejected electrons could accumulate, then measure the current produced by them would have been much easier.

To solve this problem, physicists have come up with this. First, they developed a semiconductor material that allows electrons to concentrate. And second, came up and made a special device that can be used this time to dump the stored charge to be able to repeat the cycle of accumulation and again and resume information on the radiation receiver.

— Feature we developed a semiconductor material in that, — says Dmitry Khokhlov — that, when knocked out by light electron from the atom impurities out, the charge of the atom changes, the nearest neighbors of the environment a little catching up to him — the crystal lattice slightly distorted. Therefore, an electron to, figuratively speaking, to return to the place, we have to make an extra effort. In other words, there is an energy barrier to overcome which the electron takes time and effort. Hence, there is a delay time during which electrons are ejected from the impurities in the material accumulated. They are becoming so numerous that they create is current can be measured. And so — and recording radiation at wavelengths of 176 and 241 microns. From this range, which is particularly interesting to astrophysicists.

However, and their colleagues from other, much more "mundane" areas of science spectrometer equipped with the new receiver is also very necessary. For example, to examine large organic molecule. After all, the spectrum of fluctuations in this area can provide invaluable information — and the structure of these molecules, and their number in the object. And in a world in which human efforts of the net from the point of view of environmentalists, almost no matter, it is more than necessary.

Battery News, 28.04.2004 9:50
Source: The News-Science

Like this post? Please share to your friends: