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  • Articles: DFG German National Licenses  (12)
  • 1995-1999  (6)
  • 1980-1984  (5)
  • 1975-1979  (1)
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  • Articles: DFG German National Licenses  (12)
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  • 1
    Electronic Resource
    Electronic Resource
    On Green–Cusson Ansätze and deformed supersymmetric quantum mechanics (1996)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 37 (1996), S. 5297-5309 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: Supersymmetric quantum mechanics cannot be deformed when the superposition of only a pair of usual bosons and fermions is considered, but it can if nontrivial parabosons and parafermions of the same order p of paraquantization are superposed. We take the simplest case p=2 and exhibit reducibility problems in that context by using Green–Cusson Ansätze following Macfarlane methods. Specific representations of the Lie superalgebra osp (2|2, R) play an interesting role in connection with possible deformations. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.531743
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    On supersymmetry and radial equations for three-dimensional central problems (1995)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 36 (1995), S. 641-647 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: Supersymmetric three-dimensional Schrödinger equations describing central problems do not lead, in general, to supersymmetric one-dimensional radial equations. Such a context is discussed, in connection with the two main supersymmetrization procedures (with or without spin-orbit coupling terms). The inverse problem is also considered, starting from a supersymmetric radial equation. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.531146
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Phase gratings in the visible and near-infrared spectral range realized by metastable electronic states in Na2[Fe(CN)5NO] · 2H2O (1996)
    Springer
    Applied physics 63 (1996), S. 243-248 
    Details
    ISSN: 1432-0649
    Keywords: 42.40.Pa ; 42.70.Gi ; 42.70.Ln
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Phase and amplitude gratings in the visible and near-infrared spectral range can be written in SodiumNitro-Prusside (SNP), Na2[Fe(CN)5NO] · 2H2O, single crystals by optical excitation of infinitely long-living metastable electronic states, localized in the [Fe(CN)5NO]2− anions. Hence, its photorefractive effect does not depend on dopants or defects. The refractive index is modulated by more thanΔn = 1 × 10−3 in the red (632.8 nm) andΔn = 5 × 10−4 in the near-infrared region (1047 nm). The absorption coefficient is modulated by aboutΔα = 100 m−1 at 632.8 nm and 40 m−1 at 1047 nm. The wavelength dependence ofΔn can be explained by strong absorption bands in the ultraviolet considering Kramers-Kronig dispersive analysis. The time constant of the write-read-erase processes and the diffraction efficiencyη depend on light intensity, wavelength and polarization of the light with respect to the crystallographic axes. After excitation of the metastable states the indicatrix is modulated only along thea- andb-axis of the orthorhombic system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01833793
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Phase gratings in the visible and near-infrared spectral range realized by metastable electronic states in $\rm Na_2[Fe(CN)_5NO] \cdot 2H_2O$ (1996)
    Springer
    Applied physics 63 (1996), S. 243-248 
    Details
    ISSN: 1432-0649
    Keywords: PACS:42.40.Pa; 42.70.Gi; 42.70.Ln
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. Phase and amplitude gratings in the visible and near-infrared spectral range can be written in SodiumNitroPrusside (SNP), $\rm Na_2[Fe(CN)_5NO] \cdot 2H_2O$ , single crystals by optical excitation of infinitely long-living metastable electronic states, localized in the $\rm [Fe(CN)_5NO]^{2-}$ anions. Hence, its photorefractive effect does not depend on dopants or defects. The refractive index is modulated by more than $\Delta n = 1 \times 10^{-3}$ in the red $(632.8$ nm) and $\Delta n = 5 \times 10^{-4}$ in the near-infrared region $(1047$ nm). The absorption coefficient is modulated by about $\Delta \alpha = 100$ m $^{-1}$ at $632.8$ nm and 40 m $^{-1}$ at 1047 nm. The wavelength dependence of $\Delta n$ can be explained by strong absorption bands in the ultraviolet considering Kramers-Kronig dispersive analysis. The time constant of the write-read-erase processes and the diffraction efficiency $\eta$ depend on light intensity, wavelength and polarization of the light with respect to the crystallographic axes. After excitation of the metastable states the indicatrix is modulated only along the $a$ - and $b$ -axis of the orthorhombic system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01833793
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    The Ultraviolet Spectrometer and Polarimeter on the Solar Maximum Mission (1980)
    Springer
    Solar physics 65 (1980), S. 73-90 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The Ultraviolet Spectrometer and Polarimeter (UVSP) on the Solar Maximum Mission spacecraft is described, including the experiment objectives, system design, performance, and modes of operation. The instrument operates in the wavelength range 1150–3600 Å with better than 2 arc sec spatial resolution, raster range 256 × 256 arc sec2, and 20 mÅ spectral resolution in second order. Observations can be made with specific sets of 4 lines simultaneously, or with both sides of 2 lines simultaneously for velocity and polarization. A rotatable retarder can be inserted into the spectrometer beam for measurement of Zeeman splitting and linear polarization in the transition region and chromosphere.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00151385
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Observations of the longitudinal magnetic field in the transition region and photosphere of a sunspot (1982)
    Springer
    Solar physics 81 (1982), S. 231-244 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The Ultraviolet Spectrometer and Polarimeter on the Solar Maximum Mission spacecraft has observed for the first time the longitudinal component of the magnetic field by means of the Zeeman effect in the transition region above a sunspot. The data presented here were obtained on three days in one sunspot, have spatial resolutions of 10 arc sec and 3 arc sec, and yield maximum field strengths greater than 1000 G above the umbrae in the spot. The method of analysis, including a line-width calibration feature used during some of the observations, is described in some detail in an appendix; the line width is required for the determination of the longitudinal magnetic field from the observed circular polarization. The transition region data for one day are compared with photospheric magnetograms from the Marshall Space Flight Center. Vertical gradients of the magnetic field are computed from the two sets of data; the maximum gradients of 0.41 to 0.62 G km−1 occur above the umbra and agree with or are smaller than values observed previously in the photosphere and low chromosphere.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00151299
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Vertical gradients of sunspot magnetic fields (1983)
    Springer
    Solar physics 84 (1983), S. 13-31 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In this paper, we describe results of a Solar Maximum Mission (SMM) guest investigation to determine vertical gradients of sunspot magnetic fields for the first time from coordinated observations of photospheric and transition-region fields. Both the photospheric vector field of a sunspot, derived from observations using the NASA Marshall Space Flight Center vector magnetograph, and the line-of-sight component in the transition region, obtained from the SMM Ultraviolet Spectrometer and Polarimeter instrument, are described. From these data, vertical gradients of the line-of-sight magnetic field component are calculated using three methods. (1) The vertical gradient is derived directly from the observations assuming a height difference of 2000 km between the photosphere and transition region. (2) Using the observed transverse photospheric field, the initial gradient (ΔB z/Δz) z = 0 , is calculated from the condition ▽ · B = 0. (3) Using the photospheric line-of-sight component as the boundary condition in a potential-field calculation, the extrapolated potential field at different heights is compared to the observed transition-region field; from these comparisons, an average height difference is derived and used to calculate the average vertical gradient (Δ B z/Δz). Comparisons of gradients derived from these three methods show consistent results for methods (2) and (3). Deviations of the calculated potential transverse field at z = 0 from the observed transverse component are investigated to assess the validity of gradient calculations using method (3). Since the field is shown to be very close to a potential distribution, we conclude that the vertical gradient of B z is lower than values from previous studies and the transition-region field occurs at a height of ≈ 4000–6000 km above the photosphere.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00157439
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Report on the solar physics-plasma physics workshop (1976)
    Springer
    Solar physics 46 (1976), S. 411-431 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract This report summarizes the proceedings of a meeting held on 17–20 September 1974, at Stanford University. The purpose was to explore plasma physics problems which arise in the study of solar physics. Sessions were concerned with specific questions including the following: Is the solar plasma thermal or non-thermal? What spectroscopic data are required? What types of magnetic field structures exist? Do MHD instabilities occur? Do resistive or non-MHD instabilities occur? What mechanisms of particle acceleration have been proposed? What information do we have concerning shock waves? Very few questions were answered categorically but, for each question, there was discussion concerning the observational evidence, theoretical analyses, and existing or potential laboratory and numerical experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00149863
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    Paper (German National Licenses)
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  • 9
    Electronic Resource
    Electronic Resource
    Using eclipse observations to test scintillation models (1995)
    Springer
    Solar physics 156 (1995), S. 1-5 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Near second and third contact during a solar eclipse the spatial spectrum of the solar illumination changes as the relative power at high spatial frequencies increases strongly. Since groundlevel atmospheric scintillation depends on a weighted integral of the image power spectrum, we can expect to see a measureable time dependence to solar scintillation during an eclipse. This effect was observed during an annular solar eclipse and quantitatively compared with a scintillation model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00669570
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  • 10
    Electronic Resource
    Electronic Resource
    Conductive flux in the chromosphere derived from line linear polarization observation (1983)
    Springer
    Solar physics 86 (1983), S. 115-122 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Linear polarization in two chromospheric lines (Hα and SI 1437 A) was observed in the gradual phase of solar flares. The polarized electric vector is directed towards disk center. This polarization could be due to collisional excitation of hydrogen and SI by energetic electrons beamed in the vertical direction. Direct excitation by a highly energetic beam of electrons of order 10–100 keV. is doubtful. The heat flux in the region connecting the transition zone to the high chromosphere during the gradual phase of a flare could lead to an anisotropic excitation. Selecting a function which represents the velocity distribution of electrons carrying heat flux, the relationship between conductive heat flux and linear line polarization has been computed. The application of the relationship between linear polarization and heat flux to the observed degree of polarization leads to the determination of the conductive heat flux in the high chromosphere. This conductive flux is of the order of magnitude of the total radiation loss in the chromosphere and below, which is also of the order of magnitude of the conductive flux in the transition zone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00157180
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