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931.
The analogues of the low-lying levels in71Ge have been observed as resonances in the compound nucleus71As through proton elastic scattering on70Ge in the energy rangeE
p=3.5 to 5.3 MeV. The excitation functions cover the analogue resonances corresponding to states upto 2.3 MeV excitation in71Ge. The sub-structures in the 5.06 MeV resonance, first observed by Temmer and co-workers have been confirmed in the present
experiment. The present investigation reveals similar sub-structures in the 4.13 MeV resonance lending further support to
the existence of intermediate structure near an isobaric analogue resonance. The resonance parameters and the spectroscopic
factors (for the corresponding parent states) have been extracted. The results are compared with the information available
from the70Ge(d, p)71Ge reaction. 相似文献
932.
A theory has been given for the scattering of neutrons by anharmonic crystals, for which terms of the typeV
(3) (k
1j1; —k
1j1;o
j) which contribute to the sublattice displacements are not neglected. Using the standard perturbation theory in the interaction
picture or Green’s function method, an expression has been derived for the differential scattering cross-section which brings
in the shift and the width of the phonons in one-phonon energy exchange processes. It is shown that the sublattice displacements
will modify the phase factor arising from the scattering by any atom in the unit cell, and the Debye-Waller factor also gets
altered both by the sublattice displacements as well as by higher order terms arising from anharmonicity. It is shown that
the differential scattering cross-section contains a term linearly depending on the third order anharmonicity coefficientV
(3) (k
1j1;k
2j2;k
3j3) and neutron scattering by crystals should provide a useful method for evaluating the third order anharmonicity coefficients. 相似文献
933.
934.
935.
Michael Scheutzow 《Stochastic Processes and their Applications》1985,20(2):323-331
It is shown that unlike nondegenerate (linear) diffusion processes, nonlinear diffusion processes can have a periodic law. We provide an example of a nonlinear diffusion for which periodic behavior is even created by the noise, i.e. no periodicity occurs when the noise is turned off. In the second part of the paper we give an example of a one-dimensional nonlinear diffusion which can be stabilized by noise. Finally we show also that the N-dimensional (N ≥ 2) ‘linear’ diffusion approximations of that system are stabilized by noise. 相似文献
936.
937.
基于非线性光学耦合波方程组建立了聚焦泵浦条件下熔石英玻璃材料中SBS过程的物理模型并编制了相应的数值求解程序,研究了SBS介质内激光场的时空发展特征,从而试图揭示SBS介质的内在破坏机制并寻求相应的加固措施.通过数值模拟程序研究了焦点处激光功率密度以及SBS反射率与激光能量的依赖关系,发现SBS对介质内的激光场具有"限幅"作用,即在注入能量大幅度提升的情况下,内部的激光场强度只有较小的增加,这种机制使大能量的固体介质PCM成为可能.分析激光脉宽以及耦合透镜焦距等参数对SBS过程的影响发现,精细选择系统参数,在熔石英玻璃材料中有可能无损伤地实现高效的SBS过程. 相似文献
938.
Hu X Jiao X Narayanan S Jiang Z K Sinha S Lurio LB Lal J 《The European physical journal. E, Soft matter》2005,17(3):353-359
We have used measurements of the absolute intensity of diffuse X-ray scattering to extract the interfacial tension of a buried polymer/polymer interface. Diffuse scattering was excited by an X-ray standing wave whose phase was adjusted to have a high intensity at the polymer/polymer interface and simultaneously a node at the polymer/air interface. This method permits the capillary-wave-induced roughness of the interface, and hence the interfacial tension, to be measured independently of the polymer/polymer interdiffusion. 相似文献
939.
D. I. Glazier M. Seimetz J. R. M. Annand H. Arenhövel M. Ases Antelo C. Ayerbe P. Bartsch D. Baumann J. Bermuth R. Böhm D. Bosnar M. Ding M. O. Distler D. Elsner J. Friedrich S. Hedicke P. Jennewein G. Jover Ma nas F. H. Klein F. Klein M. Kohl K. W. Krygier K. Livingston I. J. D. MacGregor M. Makek H. Merkel P. Merle D. Middleton U. Müller R. Neuhausen L. Nungesser M. Ostrick R. Pérez Benito J. Pochodzalla Th. Pospischil M. Potokar A. Reiter G. Rosner J. Sanner H. Schmieden A. Süle Th. Walcher D. P. Watts M. Weis 《The European Physical Journal A - Hadrons and Nuclei》2005,24(1):101-109
The electric form factor of the neutron, GE,n, has been measured at the Mainz Microtron by recoil polarimetry in the quasielastic D(¯e, e¯n)p reaction. Three data points have been extracted at squared four-momentum transfers Q
2 = 0.3, 0.6 and 0.8 (GeV/c)2. Corrections for nuclear binding effects have been applied.This revised version was published online in March 2005. In the previous version, the email address of one author was inadvertently assigned to multiple authors. 相似文献
940.
M.?M.?H.?El-Gogary A.?Y.?EllithiEmail author M.?Kh.?Hegab A.?A.?Mohamed 《The European Physical Journal A - Hadrons and Nuclei》2005,24(1):137-147
In the framework of the Glauber multiple-scattering theory, the elastic collisions of proton-proton (pp) at the center-of-mass energies
= 23.5, 30.7, 44.7, and 52.8 GeV and alpha-proton (p) at
= 88 and 89 GeV are analyzed by considering the quark structure of their constituents. The differential cross-section containing the full multiple-scattering series between their quarks is calculated using Gaussian forms for the quark density and quark-quark (QQ) scattering amplitudes. The results obtained from the quark model and the conventional nucleon model are compared with the experimental data. The comparison shows that the nucleon model reproduces the experimental data more satisfactorily than the quark model, and both approaches have limited success in describing the data at such energies. The agreement with the experimental data is improved by the inclusion of the phase variation. 相似文献