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[en] We report on the results of a visual search for galaxy-scale strong gravitational lenses over 650 arcmin2 of HST/ACS (F606W and F814W) imaging in the DEEP2-Extended Groth Strip (EGS). In addition to a previously-known Einstein Cross also found by our search (the 'Cross', HSTJ141735+52264, zlens = 0.8106, zsource = 3.40), we identify two new strong galaxy-galaxy lenses with multiple extended arcs. The first, HSTJ141820+52361 (the 'Dewdrop'; zlens = 0.5798), lenses two distinct extended sources into two pairs of arcs (zsource = 0.9818), while the second, HSTJ141833+52435 (the 'Anchor'; zlens = 0.4625), produces a single pair of arcs (zlens not yet known). Four less convincing arc/counter-arc and two-image lens candidates are also found and presented for completeness. Lenses are found in a both underdense and overdense local environments, as characterized by a robust measure, 1+(delta)3, a normalized density that uses the distance to the third nearest neighbor. All three definite lenses are fit reasonably well by simple singular isothermal ellipsoid models including external shear, giving χν2 values close to unity. These shears are much greater than those implied by a simple consideration of the three-dimensional convergence and shear from galaxies along the line of sight, where each galaxy is approximated by a singular isothermal sphere halo truncated at 200 h-1 kpc. This shows how a realistic treatment of galaxies and the large scale structure they are embedded in is necessary, and that simply characterizing the very-local environment may be insufficient
[en] In this research a detailed investigation was carried out on two experimental lenses, one with a cylindrical pole and the other with a spherical pole. The asymmetrical magnetic field distribution of the single pole-piece lens for both cylindrical and spherical shapes was studies and an analytical comparison between them was made. The results of this reseacher are useful in the construction of the single pole-piece magnetic electron lens when used in the transmission electron microscope or scanning transmission electron micoscope for achieving low distortions and aberrations and high resolving power.(2 tabs., 48 figs., 24 refs.)
[en] The finite element method has been used to investigate the design of asymmetrical leneses with double spherical polepieces. The axial magnetic field distribution has been coputed for every bore size in the polepieeces at different values of air gap S between the two poles. The importance of this work lies in the possibility of designing asymmtrical electron lenses with double sperrations polepieces used as an objective lens with low aberrations and high resolving power and as aprojector lens with lowest distortions in both transmission electron microscope (TEM) and scanning transmission electron microscope (STEM).(4 tabs., 54 refs., 32 refs.)
[en] Results are presented from studies of the focusing of wide-aperture low-energy (100-400 eV) and moderate-energy (5-25 keV) beams of heavy-metal ions by a high-current electrostatic plasma lens. It is found experimentally that, because of the significant electron losses, the efficient focusing of such beams can be achieved only if the external potentials at the plasma-lens electrodes are maintained constant. Static and dynamic characteristics of the lens are studied under these conditions. It is shown that, as the beam current and the electrode voltage increase, the maximum electrostatic field in the lens tends to a certain limiting value because of the increase in the spatial potential near the lens axis. The role of spherical and moment aberrations in the focusing of wide-aperture low-divergence ion beams is revealed. It is shown that, even when spherical aberrations are minimized, unremovable moment aberrations decrease the maximum compression ratio of a low-energy heavy-ion beam because of the charge separation of multiply charged ions in the focal region. At the same time, as the ion energy increases, the role of the moment aberrations decreases and the focusing of high-current heavy-ion beams by a plasma lens becomes more efficient than the focusing of light-ion (hydrogen) beams. This opens up the possibility of using electrostatic plasma lenses to control ion beams in high-dose ion implanters and high-current accelerators of heavy ions
[en] When the gravitational lens is a galaxy or galactic cluster, the effect of geometrical dimensions of the lens on the separation between the source and the image has been studied by using the thin lens approximation. A new form of the lens equation has been found. This equation shows the relationspips between the basic parmeters of the lens and helps in studying the distribution in the galaxy or galacic cluster that behaves as a lens. This research clarifies that, at a very large distance between the observer and the lens, the effect of distance from the observer to the lens on the image position decreases. Also, it shows that the effect of the impact parameter in the thin lens approximation is opposite to that which appears in the point mass approximation. (authors).
[en] This retrospective sketches the evolution of emission electron microscopy, low energy electron microscopy and related methods from the early stages up to the present state and gives a brief outlook on the future possibilities of these cathode lens electron microscopy techniques. It is concerned mainly with instrumentation, discusses some little known work and emphasizes important steps in the evolution of the field instead of attempting to review it in detail.