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A. Hotzel P. Thirolf Ch. Ender D. Schwalm M. Mutterer P. Singer M. Klemens J. P. Theobald M. Hesse F. Gönnenwein H. v. d. Ploeg 《Zeitschrift für Physik A Hadrons and Nuclei》1987,356(3):299-308
The γ-ray spectrum of 252Cf(sf) was measured in the Darmstadt-Heidelberg Crystal Ball spectrometer, with a double ionization chamber mounted inside to detect the fission fragments. The measurement was aimed at a better understanding of an unusual component found in the high-energy region between 3 and 8 MeV, with fragment mass splits near symmetry. This component was proved to be predominantly emitted by the heavier fragment, to reach its highest intensity at a fragment mass split of 132:120, and to have an almost isotropic angular distribution. Calculations with the statistical code CASCADE could reproduce the main features. 相似文献
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P. Singer M. Mutterer Yu. N. Kopach M. Klemens A. Hotzel D. Schwalm P. Thirolf M. Hesse 《Zeitschrift für Physik A Hadrons and Nuclei》1997,359(1):41-45
An experiment was performed on prompt γ-ray emission in binary and α-particle accompanied spontaneous fission of 252 C f using the Darmstadt-Heidelberg 4π NaI Crystal Ball spectrometer. The enhancement in γ-ray yield, denoted as the “high-energy component”, which appears between 3.5 and 8 MeV and in the region of near-symmetric fragment mass splits, was observed to be equally pronounced in both fission modes. Analyzing the fragment mass dependence of the mean γ-ray multiplicity in both fission modes clearly identifies the disintegration of equilibrated fission fragments in a narrow mass range around the double-magic 132Sn as the source of these γ-rays. 相似文献
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Glasses in the system TeO2/Nb2O5/ZnO/CdS were studied with respect to the density, molar volume, refractive index, polarizability, molar refraction, metallization and third order non-linear optical susceptibility. The third order non-linear optical susceptibilities, χ(3), were measured using degenerate four-wave mixing (DFWM). The addition of CdS to TeO2-based glasses leads to increasing refractive as well as the non-linear refractive indices. The largest measured value of the third order non-linear optical susceptibility was 7.8 × 10?13 esu and has been found in the 90TeO2 · 5Nb2O5 · 5ZnO · 0.4 CdS glass. The non-linear optical susceptibility increased with increasing CdS-concentration. In order to estimate the third order non-linear optical susceptibility, the theoretical model of Lines and the empirical equation of Miller were used. 相似文献
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S. Kwiet D.E. Starr A. Grujic M. Wolf A. Hotzel 《Applied physics. B, Lasers and optics》2005,80(1):115-123
The photodesorption mechanism of H2O from quartz-supported silver nanoparticles has been studied by femtosecond laser two-pulse correlation and fluence dependence measurements. With the laser wavelength close to the maximum of the (1,1) plasmon resonance of the nanoparticles, the desorption was found to be purely thermal, i.e., induced by coupling of the desorption coordinate to the nanoparticle lattice temperature, both in the low- and the high-coverage regimes. The lattice cooling times of the nanoparticles are in the range of several hundred ps, in accordance with recent time-resolved X-ray measurements. Also observed is a reversible red-shift of the nanoparticle plasmon modes with increasing H2O coverage which is attributed to dielectric screening. PACS 78.67.-n; 82.53.-k; 65.80.+n 相似文献