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  • 1
    Electronic Resource
    Electronic Resource
    Optical pumping of ions in buffer gases (1973)
    Springer
    The European physical journal 259 (1973), S. 371-390 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Transient signals measured with a pulsed rf-optical pumping method are used to determine longitudinal relaxation rates for Sr+ ions (even isotopes) in noble gas buffers. Depolarization cross sections of the electronic spin in the Sr+52 S 1/2 ground state for binary collisions with rare gas atoms are deduced. The results for σ(Sr+52 S 1/2) in Å2 are (at temperatures between 374 and 449 °K): 2·10−5(He),4·10−5(Ne), 5.7·10−3(Ar), 1.8·10−2(Kr), and 4.0·10−2(Xe). These cross sections for the Sr+ ion are about two to three orders of magnitude larger than the corresponding ones for the isoelectronic neutral Rb atom. The large increase of the Sr+ relaxation rates is explained with the relaxation mechanism of spin-orbit coupling, taking into account two “indirect” effects of the ionic charge: the increase in the gas kinetic cross sections and the more intimate collisions of the Sr+ ion with the noble gas atoms. The depolarization is shown to be predominantly due to short-range interactions. A contribution to the relaxation of the Sr+ ion from Sr+-noble gas molecule formation, induced by three-body or resonant two-body collisions, could not be established for applied pressuresp between 1.5 and 15 Torr of Ar, Kr, and Xe.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01397375
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  • 2
    Electronic Resource
    Electronic Resource
    Optical pumping of ions in buffer gases (1973)
    Springer
    The European physical journal 260 (1973), S. 341-350 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Optical pumping with the D2 resonance line can result in a zero2 S 1/2 ground state polarization at a particular buffer gas pressurep 0. For the even isotopes of Sr+ ions, the corresponding relaxation rate Γ1 of the dipolar polarization in the2 P 3/2 excited state can be calculated as a function of the mean lifetime τ of this state directly from the condition of zero2 S 1/2 ground state polarization. The calculation includes the branching decays of the 52 P 3/2 state to the 52 S 1/2 and 42 D 5/2,3/2 states, the collisional quenching from2 P and2 D states, and the diffusion of the Sr+ ions. From the calculated relaxation rate Γ1 and the measured value ofp 0, the cross sections for the destruction of the dipolar polarization in the2 P 3/2 state are obtained, σ1(Sr+52 P 3/2) in Å2: 72±9(He), 80±10(Ne), 124±15 (Ar), 148±18 (Kr), and 196±23 (Xe). The values of σ1 for the Sr+ ion are of comparable magnitude to those for the isoelectronic Rb atom.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01397958
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  • 3
    Electronic Resource
    Electronic Resource
    Relaxation and deorientation of110Ag(T 1/2=24.4s) nuclei produced by capture of polarized neutrons in the silver halides (1973)
    Springer
    The European physical journal 262 (1973), S. 189-210 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Polarized110Ag nuclei are produced in the silver halides by capture of polarized neutrons at temperatures below 30 K and magnetic field strengths up to 6 kOe. The depolarization process is studied by observation of the β decay asymmetry as a function of magnetic field, temperature and of the radio frequency field strength in NMR signals. The depolarization is caused by a field dependent deorientation process and by temperature dependent spin-lattice relaxation. The deorientation is due to a succession of coupling steps of the nuclear spin with electromagnetic fields of defects generated as a consequence of the capture process, and the field dependence of the polarization can be understood as a decoupling curve. The temperature dependence of the spin-lattice relaxation is in accordance with the theory of quadrupolar relaxation above 18 K if an empirical phonon spectrum is used for the calculation. At lower temperatures the experimental relaxation rate is anomalously high, which may be due to resonance modes connected with recoil lattice defects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01391836
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  • 4
    Electronic Resource
    Electronic Resource
    Relaxation phenomena and nuclear magnetic resonance of116In(T 1/2=14s) produced by capture of polarized neutrons in the indium III–V compounds (1971)
    Springer
    The European physical journal 244 (1971), S. 289-311 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Polarized116In nuclei have been produced by capture of polarized thermal neutrons in several In compounds. At temperaturesT below 77 °K and magnetic field strengthsH 0 of several kOe, asymmetries of a few percent of the β− decay of the116In ground state could be observed in polycrystalline InP, InAs and InSb, thus indicating the nuclear polarization. Nuclear magnetic resonance signals have been measured with the result for the magnetic moment μ i (116In)=2.7723 (10) nm (uncorrected). β− decay asymmetry and spin lattice relaxation timeT 1 have been studied as a function ofH 0 andT. The effect ofH 0 is to decouple the hyperfine interaction caused by the capture-γ recoil process. However,H 0 has no influence uponT 1, which demonstrates the absence of nuclear relaxation due to paramagnetic impurities.T 1 is determined by quadrupolar relaxation. A quadrupole momentQ(116In)=0.09 (2) b was calculated by comparison of the116In relaxation rates with those of the stable115In isotope in the same compounds. Above 30 °K the temperature dependence of 1/T 1 agrees with a recent theoretical investigation. Below 30 °K the relaxation rate shows an anomalous behaviour, which can be explained by resonance modes due to recoil lattice defects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01396789
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  • 5
    Electronic Resource
    Electronic Resource
    Cross-relaxation processes of polarizedβ-active nuclei in various crystalline solids (1980)
    Springer
    The European physical journal 37 (1980), S. 151-161 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Cross-processes of neutron activated, polarized nucleiI with surrounding stable host nucleiS are observed in diverse solids, using an in-beam NMR technique where the polarizedI nuclei are produced by capture of polarized thermal neutrons. The polarization is determined by measuring the 0°–180° asymmetry of theβ-decay radiation of these nuclei. The following cross-processes are studied:8Li−6Li innatLi metal;8Li−7Li in7Li metal;8Li−6Li innatLiF (single crystal);8Li−93Nb in7LiNbO3 (single crystal);20F−19F in MgF2 (single crystal). Two applications are presented: a) Determination of the temperature dependence of the electrical quadrupole coupling constant of93Nb in LiNbO3; b) Observation of radiation induced point defects in MgF2 and their thermal annealing. All measurements are performed without any radiofrequency irradiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01365371
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  • 6
    Electronic Resource
    Electronic Resource
    Experimental allergic encephalomyelitis (1981)
    Springer
    Acta neuropathologica 54 (1981), S. 149-152 
    Details
    ISSN: 1432-0533
    Keywords: Experimental allergic encephalomyelitis ; Blood ; Brain barrier ; Fibrinogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Classical acute allergic encephalomyelitis (EAE) was provoked in Lewis rats with bovine spinal cord (BWM) in complete Freund's adjuvant (CFA). An efficient immunohistologic technique (peroxidase-antiperoxidase (PAP)) was used to trace exsudates of fibrinogen and immunoglobulin as well as their coexistence with cellular infiltrates and clinical signs. Exsudation was restricted to the vessels exhibiting cellular infiltrates. The findings do not lend support to the assumption that exsudation of circulating factors is the initial local event in EAE. It also remains open, whether the exsudation of fibrinogen and gamma globulin are responsible for the clinical symptoms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00689408
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  • 7
    Electronic Resource
    Electronic Resource
    Vorkommen von phosphororganischen Insecticiden im Fetus (1970)
    Springer
    Archives of toxicology 26 (1970), S. 17-22 
    Details
    ISSN: 1432-0738
    Keywords: Organophosphate Insecticides ; Fetus ; Phosphororganische Insecticide ; Fetus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Nach Applikation von Methylparathion, Bromophos und Imidan an trächtige Albinoratten sind diese Wirkstoffe in der Placenta sowie in Leber, Gehirn und Muskelgeweben der Feten nachweisbar. Das PO-Isologe konnte beim Methylparathion in allen untersuchten embryonalen Geweben festgestellt werden. Bei den mindertoxischen Insecticiden Bromophos und Imidan war lediglich das PO-Isologe des Bromophos, das Bromoxon, in Spuren im Muskelgewebe der Feten nachweisbar.
    Notes: Summary Following application of Methylparathion, Bromophos and Imidan in pregnant albino rats, these compounds are detectable in the placenta as well as in the liver, brain and muscle tissue of the fetus. The organophosphate isologe of Methylparathion could be found in all embryonic tissue studied. By the less toxic insecticides Bromophos and Imidan, only traces of the Bromophos isologe Bromoxon could be detected in the muscle tissue of the fetus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00577963
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  • 8
    Electronic Resource
    Electronic Resource
    8Li spin relaxation in liquid Li alloys with compound-forming tendency (1983)
    Springer
    Hyperfine interactions 16 (1983), S. 569-572 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In liquid Li-Bi, Li-Pb, Li-Sn and Li-Si alloys the spinlattice relaxation rate T 1 −1 of Β-active8Li (T1/2=0.8s) probe nuclei has been measured over wide concentration (c) and temperature (T) ranges. T 1 −1 is governed by hyperfine contact interaction with the conduction electrons. Near the compositions Li3Bi, Li4Pb, Li4Sn and Li4Si both (T1T)−1 and d(T1T)−1/dT versus c show marked extrema. These data, when combined with Knightshift and/or conductivity values, inform on the prolongation of the electron “residence time” and the reduction of the density of states at the Fermi surface. There is progressive tendency to electron localization and compound formation in the sequence Li4Pb, Li4Sn, Li3Bi with mainly ionic bonding in the case of liquid Li3Bi.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02147317
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  • 9
    Electronic Resource
    Electronic Resource
    Experimental test of electroweak effects at PETRA energies (1981)
    Springer
    The European physical journal 7 (1981), S. 289-293 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The differential cross sections for Bhabha scattering and μ pair production, and the total τ pair cross section as measured by the PLUTO detector at PETRA, have been analyzed to extract information on the weak interaction of leptons. The data are compared with unified gauge theories. Since the observed electroweak effects are still consistent with zero (within errors) we can set experimental limits on neutral current parameters atQ 2 values of 950 GeV2. In the framework of the standard SU(2)×U(1) model we find sin2 Θ w 〈0.52(95% c.l.). In the context of general singleZ o models we can excludeZ o masses of less than 40 GeV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01431561
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  • 10
    Electronic Resource
    Electronic Resource
    Energy dependence of jet measures ine + e − annihilation (1982)
    Springer
    The European physical journal 12 (1982), S. 297-306 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The jet character of the hadronic final states produced ine + e − annihilations is studied in terms of jet measures such as thrust, sphericity, jet opening angle and jet masses, in the energy range 7.7 to 31.6 GeV. All distributions and averages have been corrected for detector effects and initial state radiation. The energy dependence of the averages of these jet quantities is used to estimate the contributions due to perturbative QCD and fragmentation effects. Correlations between the jet measures and the multiplicity of charged hadrons are also presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01557575
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