Results 1 - 10 of 7282
Results 1 - 10 of 7282. Search took: 0.026 seconds
|Sort by: date | relevance|
[en] A facility for the production of 10 MeV polarized neutrons was designed and built. Neutron polarization and cross section can be measured over an angular range of 2-100 deg. This facility has been used to measure the polarization and cross section of 10 MeV neutrons scattered from Pb and Bi in an angular range of 1.5 to 65 deg. For small angles no significant difference was found in the results for Pb and Bi. DWBA calculations using only the nuclear and Mott-Schwinger ineractions give good agreement with the data. Comparison of the experimental results with predictions using three different global optical potentials proved that the Becchetti and Greenlees potential can best describe both the differential cross section and polarization in the scattering of 10 MeV neutrons from heavy elements. (LL)
[en] In view of the importance of the equivalence between the prior-interaction and post-interaction forms for the validity of distorted-wave Born-approximation (DWBA) studies in reactive scattering, we present a comparison study between the two forms by illustrating a reactive atom--diatomic-molecule system. Our DWBA method presented earlier is found to satisfy the condition of the equivalence remarkably well
[en] I revisit a longstanding question in quantum optics; when is the rotating wave approximation justified? In terms of the Jaynes–Cummings and Rabi models I demonstrate that the approximation in general breaks down in the adiabatic limit regardless of system parameters. This is explicitly shown by comparing Berry phases of the two models, where it is found that this geometrical phase is strictly zero in the Rabi model contrary to the non-trivial Berry phase of the Jaynes–Cummings model. The source of this surprising result is traced back to different topologies in the two models. (paper)
[en] The theory of Faddev/AGS few body reaction frameworks is presented. A comparison with other reaction formalisms (DWBA, CDCC) is made. Sucesses and shortcomings of the scattering approaches for breakup are analysed. Some set of calculated reaction observales for resonant and nonresonant breakup are presented to obtain insight into the physics incorporated on the scattering approaches.
[en] The formalism for using nonspherical potentials within the framework of a first-order distorted-wave approximation was presented recently by Madison, Bartschat, and Peacher. They investigated the electron-impact excitation of the of hydrogen. The standard approach with the 2p state as the excited state leads to a nonspherical quadrupole potential. Their results indicated that the effects of this nonspherical quadrupole distortion were negligible for all practical purposes. However, the 2s state of hydrogen interacts strongly with the 2p state. Thus we have considered using the Stark states to represent the excited atomic states. This leads to a nonspherical dipole distortion in the final-state potential. First-order distorted-wave results will be presented for a range of energies
[en] The electron capture to the continuum phenomenon in positron impact ionization of helium is studied with the DWBA approximation. Our DWBA-WM model produces results which are in better agreement with the experiment than the more elaborate 3C model.