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991.
The analysis of nuclear convection-current contributions to the transverseE 2 isoscalar and isovector form factors in12C initiated by Flanz et al. has been extended. It is shown that the continuity equation of the nuclear electromagnetic current provides the constraint needed to explain the behaviour of the form factors studied in the range 0<q<2fm–1. 相似文献
992.
R. Broda P. J. Daly J. McNeill R. V. F. Janssens D. C. Radford 《Zeitschrift für Physik A Hadrons and Nuclei》1987,327(4):403-408
The level structure of theN=81 nucleus149Er has been studied by γ-ray spectroscopy following the reaction92Mo+255 MeV60Ni. Yrast levels in149Er are established up to ~3.3 MeV, including 0.61 and 4.8 μs isomeric states. Most of the observed levels are interpreted as seniority-three states arising from the coupling of s1/2, d3/2 and h11/2 neutron holes with πh 11 2/n . Isomers identified in the reaction96Ru+255 MeV58Ni are tentatively assigned to151Yb. TheB (E2) values of high-spin isomers inZ=66?70,N=81?83 nuclei are surveyed. 相似文献
993.
H. Prade J. Döring W. Enghardt L. Funke L. Käubler 《Zeitschrift für Physik A Hadrons and Nuclei》1987,328(4):501-502
An (α, 2nγ) in-beam study of excited states in 142Nd revealed 27 new levels on top of the 6+ isomer. Nanosecond lifetimes were found for two levels. The measured excitation energies were compared with spherical shell-model predictions obtained from suitably truncated model spaces. 相似文献
994.
A quasi-linear Si2O molecule model (QLMM) is suggested from an analysis of the configuration and the interactions of an isolated oxygen atom with its neighbor silicon atoms. The vibrational modes are assigned and the infrared absorption spectra are calculated in detail with the model. The theoretical results are in reasonably good agreement with reported experimental values. This agreement shows that for the analysis of the vibrational modes of the interstitial oxygen atom in silicon crystals it is not necessary to consider the coupling of the molecule with the rest of the lattice. The interaction of the oxygen atom with its six second-nearest silicon atoms only causes the level separation of the
2 mode and the formation of the fine structure. 相似文献
995.
D. Rein 《Zeitschrift fur Physik C Particles and Fields》1987,35(1):43-64
A partial wave decomposition of \({v \mathord{\left/ {\vphantom {v {\bar v}}} \right. \kern-0em} {\bar v}}\) single pion production is used for studying resonant and nonresonant contributions. The dominant resonance excitation is dynamically described by a semirelativistic quark model. Nonresonant background is considered to arise from Born-terms diminuished by the lowest order partial waves (which are determined by resonances alone.) The method permits evaluation of interferences between resonance and background amplitudes as well as, more importantly, among resonances themselves. Predicted interference patterns are reflected by the pion angular distribution coefficients which compare well with recent data. Results obtained this way are also in agreement with momentum transfer measurements if higher resonance excitation form factors are chosen to resemble those tested in pion photoproduction, rendering simultaneously any nonresonant background small. 相似文献
996.
D. Bazzacco F. Brandolini K. Löwenich P. Pavan C. Rossi-Alvarez 《Zeitschrift für Physik A Hadrons and Nuclei》1987,328(3):275-279
The 2 1 + level of138Ba has been Coulomb excited with a 105 MeV32S beam. The precession of the gamma ray angular distribution induced by the transient magnetic field when traversing a 2.14 mg/cm2 iron foil, has been measured to be 15.6(1.7) mr. A value of g(138Ba 2 1 + )=0.72(11) was obtained assuming for the transient field strength the Chalk River calibration. The field parametrization has been checked using the first 2+ state in150Sm as probe. Theg value obtained is sensibly lower than predicted by large scale shell model calculations in a proton subspace. Theg-factor of the first 2+ state in148Sm has been remeasured yieldingg(148Sm 2 1 + )=0.246(22). 相似文献
997.
E. Van Walle D. Vandeplassche J. Wouters N. Severijns L. Vanneste 《Hyperfine Interactions》1987,34(1-4):105-109
Since the previous conference we extended our series of on-line -anisotropy measurements in the Z=50 and Z=82 region leading a.o. to the identification of the phase transition in the Au isotopes. Besides conventional on-line low temperature nuclear orientation, we introduced the first on-line applications of NMR/ON, on-line -anisotropy measurements and -decay asymmetry experiments. The intriguing information from these new developments both in the field of nuclear structure and solid state physics is briefly discussed. 相似文献
998.
Since the polarization structure of reactions in the collinear directions is greatly simplified, since reactions at very high energies tend to be predominantly close to collinear, and since the one-particle exchange mechanisms are more pronounced in the forward direction, tests of one-particle-exchange (OPE) mechanisms are formulated for collinear reactions. The number of amplitudes are derived for a reaction with arbitrary spins, and examples for the practically occurring cases are given. The results are applied to the reaction 1/2+1/21+1 and in particular ton+pd+ (or to its inverse). A detailed procedure is outlined for a step-by-step testing of the various OPE processes in this reaction through a series of polarization experiments. In particular, the tests can separate out theJ=0 andJ=1/2 OPE processes. 相似文献
999.
1000.