Home About us Contact
|
Home About us Contact | ||
|
|
||
Fast Electrons (fast + electron)
Selected AbstractsElectron,cyclotron maser observable modesMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2000A. Stupp We investigate wave amplification through the electron,cyclotron maser mechanism. We calculate absorption and emission coefficients without any approximations, also taking into account absorption by the ambient thermal plasma. A power-law energy distribution for the fast electrons is used, as indicated by X-ray and microwave observations. We develop a model for the saturation length and amplification ratio of the maser, scan a large parameter space and calculate the absorption and emission coefficients for every frequency and angle. Previous studies concluded that the unobservable Z mode dominates in the ,p,,B region, and that millisecond spikes are produced in the region ,p,B<0.25. We find that the observable O and X modes can produce emission in the 0.8<,p,B<2 region, which is expected at the footpoints of a flaring magnetic loop. The important criterion for observability is the saturation length and not the growth rate, as was assumed previously, and, even when the Z mode is the most strongly amplified, less strongly amplified O or X modes are still intense enough to be observed. The brightness temperature computed with our model for the saturation length is found to be of order 1016 K and higher. The emission is usually at a frequency of 2.06,B, and at angles of 30°,60° to the magnetic field. The rise time of the amplified emission to maximum is a few tenths of a millisecond to a few milliseconds, and the emission persists for as long as new fast electrons arrive in the maser region. [source] Defect-impurity interactions in irradiated tin-doped Cz-Si crystalsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2003L. I. Khirunenko Abstract Results of a combined infrared absorption (IR) and deep-level transient spectroscopy (DLTS) study of defects induced by irradiation with fast electrons in Sn-doped Czochralski-grown Si crystals are reported. Tin atoms were found to interact effectively with vacancy as well as with interstitial-type radiation-induced defects. Manifestations of stable tin-vacancy and tin-interstitial carbon atom complexes were observed in DLTS and IR absorption spectra. Defect transformations upon heat-treatments of the irradiated samples were studied. Tin atoms were found to be effective traps for mobile vacancy,oxygen (V,O) complexes. A local vibrational mode of a Sn,V,O complex has been identified. [source] Radiation-induced defects and their transformations in oxygen-rich germanium crystalsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2003V. P. Markevich Abstract Defects induced by irradiation with fast electrons and 60Co gamma-rays in oxygen-rich Ge crystals have been studied by means of infrared absorption, deep level transient spectroscopy (DLTS) and Hall effect measurements. It is found that the vacancy,oxygen (V,O) complex in Ge has three charge states (doubly negative, singly negative and neutral ones) and two corresponding energy levels in the gap at about Ec,,,0.21 eV and Ev + 0.27 eV. Three absorption bands at 621.4, 669.1 and 716.2 cm,1 are identified as oxygen-related asymmetrical stretching vibrations for the neutral, singly negatively charged and doubly negatively charged states of the V,O complex, respectively. [source] | ||||||||||