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| Issue 4, 2024 |
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Extracts from the Internet | ||
Nobelium-2541 November 1998Atoms with atomic numbers above 92 (trans-uranian elements) are all but absent in nature. Researchers at Argonne National Laboratory produce heavy atoms by directing calcium nuclei at a lead target in the ATLAS accelerator. In this process a small fraction of nobelium-254 is obtained, whose nucleus consists of 102 protons and 152 neutrons and has a relatively long lifetime of 55 sec. The nuclei are created within a so-called `Gamma sphere,' a spherically shaped device lined by gamma detectors which sample gamma photons from newly created, highly excited and spinning nuclei. Having passed a mass analyzer, nuclei go to a silicon detector, to be identified by the way they decay into lighter fragments. The nobelium-254 is the heaviest nucleus whose gamma spectrum has been studied in detail so far. A 20% non-sphericity of the nuclei is reported, and the possibility for this heavy nuclei to sustain an angular moment of ≈14h by is shown. Source: Physics News Update, Number 397 Electron diffraction on a fullerene1 November 1998A. Solov'ev and his colleagues in St. Petersburg developed a new techniques for the study of large molecules and atomic clusters by means of electron diffraction. Using a 809 eV electron beam, a gas of spherical C60 fullerenes was investigated. The effective electron wavelength was chosen to be smaller than the size of the fullerene molecule but larger than the intercarbon atom spacing. The angular and energy distributions of scattered electrons were studied. The technique proved very useful for the study of the molecule's surface electrons. In particular, a number of plasmon modes were detected, of which only one had been previously reported. In the authors' opinion, in such experiments also the surface charge distribution and polarizability of the C60 molecule as well as the properties of more complex molecules, e. g., proteins, can be examined. Source: http://publish.aps.org/FOCUS/ Photon molecule1 November 1998In 1997, A Forchel, T. Reinecke and their colleagues created a ‘photonic atom’, a quantum system consisting of a single photon in a micron-size semiconductor cavity. By connecting two such ‘atom’ by a microscopic bridge, a `photonic molecule' was obtained in more recent experiments. As is the case with the hydrogen molecule, also the energy levels of the photonic molecule are observed to shift and split. The `photonic molecule' is the first step towards the creation of more complex structures of a larger number of `photonic atoms,' to which desired properties may be given. Source: http://ojps.aip.org/prlo/top.html Gamma radiation blast1 November 1998On August 27, 1998, for the first time, significant changes in the Earth's ionosphere were detected, caused by an energy flow from outside of the solar system. A 5-min high-power blast of gamma radiation caused an effect comparable to oscillations normally observed during a day in ionospheric activities. The phenomenon caused a partial violation of radio communication. A similar situation is observed during solar blasts. A blast of gamma and X-ray radiation was also detected by a number of space vehicles. The radiation source is believed to be a neutron star which was detected earlier due to its pulsed X-ray radiation. Such neutron stars are called magnetars due to their high magnetic field of 1015Gauss, 100 times that in ordinary neutron stars. The blast presumably occurred during the fault of the neutron star's core which caused charged particles to accelerate in a magnetic field. Source: http://unisci.com/ Distant galaxies1 November 1998Extremely weak galaxies about 12×109 light years away have been detected using an infrared chamber and a multi-object spectrometer mounted on the Hubble telescope. The large red shift due to the expansion of the Universe make these galaxies invisible in the optical range. Some galaxies have blue colored knots in their structure, which were earlier considered as separate galaxies but turned out to be in fact regions of active star formation. Possibly, the detected galaxies are still at very early stages of their formation. A new generation telescope, to be launched in 2007, seems to hold particular promise for progress in the study of such objects. Source: http://www.stsci.edu/ |
The Extracts from the Internet is a section of Uspekhi Fizicheskih Nauk (Physics Uspekhi) — the monthly rewiew journal of the current state of the most topical problems in physics and in associated fields. The presented News is devoted to the fundamental discoveries of physics and astrophysics. Permanent editor is Yu.N. Eroshenko. It is compiled from a multitude of Internet sources. | |
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