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101.
W. Schatz P. T. Lang T. Kass M. A. Heusinger K. F. Renk 《International Journal of Infrared and Millimeter Waves》1992,13(6):853-867
In this paper we report on the determination of the spectral width of Raman gain regions for different far infrared laser gases using a metal mesh Fabry Pérot interferometer. By use of broadband pump radiation emitted from a high pressure CO2 laser we generated far infrared radiation within the Raman gain regions via stimulated Raman scattering. The spectral width of the far infrared radiation was determined using a Fabry Pérot interferometer in high interference order. We applied the method to study stimulated Raman scattering in D2O and methylfluoride at different gas pressures. 相似文献
102.
J. Grenzer E. Schomburg A. A. Ignatov K. F. Renk D. G. Pavel'ev Yu. Koschurinov B. Ja. Melzer S. Ivanov S. Schaposchnikov P. S. Kop'ev 《Annalen der Physik》1995,507(4):265-271
We report the observation of frequency multiplication of microwave radiation in a GaAs/AlAs semiconductor superlattice at room temperature. We observed, for a fundamental frequency of 9 GHz, second and third harmonic generation. We associate the harmonic generation with a nonlinear current-voltage characteristic that is determined by Bloch oscillations of electrons propagating along the superlattice axis. Our results suggest for the frequency multiplication an upper limit in the tetrahertz frequency range. 相似文献
103.
R. Baumgartner W. Eisfeld G. Pauli K.F. Renk N. Riehl 《Solid State Communications》1978,27(11):1105-1107
High-frequency acoustic phonons are detected in a ZnO crystal by phonon- induced luminescence radiation. Our experiments indicate that this radiation is caused by recombination processes of carriers captured at very shallow traps with an ionization energy of about 4 meV. Propagation of the phonons is studied by a time of flight method. 相似文献
104.
Experimental data are used to constrain the parameters of the six quark mixing model and of a composite quark model. A combined fit of the mixing angles in the Kobayashi-Maskawa scheme gives sinθ 1=0.228±0.011 and error contours around the best values sinθ 2=0.12 and sinθ 3≈0. From this, a limit of τ B >0.35×10?13 s for the mean lifetime of bottom-flavoured hadrons is obtained. For the composite quark model of Katsumata and Tomozawa, a value of τ B =(0.22?0.23)10?13 s is derived. 相似文献
105.
Experimental data on the fragmentation of charmed quarks produced in neutrino ande + e ? reactions are compared. The resulting hard fragmentation functions agree mutually. They are parametrized in two ways suggested by kinematical considerations. 相似文献
106.
The pattern of angular correlations of hadrons with a (semi-)hard trigger hadron in heavy-ion collisions has attracted considerable interest. In particular, unexpected large angle structures on the away side (opposite to the trigger) have been found. Several explanations have been brought forward, among them Mach shockwaves and Cherenkov radiation. Most of these scenarios are characterized by radial symmetry around the parton axis, thus angular correlations also determine the rapidity dependence of the correlation. If the observed correlations are remnants of an away side parton after interaction with the medium created in the collision, pQCD allows to calculate the distribution P(y) of the away side partons in rapidity. The measured correlation then arises as a folding of P(y) and the rapidity structure of the correlation taking into account the detector acceptance. This places non-trivial and rather stringent constraints on the underlying scenario. We investigate these dependences and demonstrate that Mach shockwaves survive this folding procedure well whereas Cherenkov radiation scenarios face new challenges. 相似文献
107.
T. Renk 《The European Physical Journal A - Hadrons and Nuclei》2001,11(3):251-255
Following a prior analysis of measured pp elastic differential cross-sections, the impact parameter representation in terms of profile functions is calculated from
two different parametrizations of single diffractive dissociation data. The derivative of this quantity, with respect to the
collision energy squared s, measures the growth rate of the reaction's blackness. Its distribution in impact parameter space allows detailed insight
into the growth pattern of the total diffractive cross-section and the approaching unitarity limit. Comparing the results
with the elastic case, the different mechanisms of unitarization of two parametrizations are discussed.
Received: 19 January 2001 / Accepted: 11 July 2001 相似文献