Corrections to the Glauber multiple scattering series

ANNALS

OF PHYSICS 94,

Abstracts

Corrections SHARMA.

417-418 (1975)

of Papers

to Appear

in Future

Issues

to the Glauber Multipie Scattering Series. H. BANERJEE, B. DUTTA-ROY, Saha Institute of Nuclear Physics, Calcutta-700009, India.

AND S.

K.

The asymptotic accuracy of the Glauber multiple scattering formula is examined in the fixed scatterer approximation in one dimension. If the potentials overlap, the off-shell corrections that dominate are asymptotically of the same order as the corrections to the eikonal approximation results. In the case of nonoverlapping potentials, the corrections to the Glauber formula arise from multiple scattering. The asymptotic behavior of these latter corrections depends essentially on the smoothness of the potentials. Absorption and Defocusing of Electromagnetic Radiation by a Schwarzschild Black Hole. Wrctc HAXTON, Institute of Theoretical Physics, Stanford University, Stanford, California 94305 AND REMO RUFFINI. Institute for Advanced Studies, Princeton University, Princeton, New Jersey

08540. A comparison of electromagnetic radiation absorbed by a black hole and that emitted at infinity is made for selected circular orbits of a charged particle in a Schwarzschild geometry. Radiation intensity and beaming processes for geodesic as well as ultrarelativistic unbound orbits are compared and contrasted with the special relativistic results of classical electrodynamics. Nuclear

Viscosity

and

Widths

of Giant

partment of Physics and Astronomy,

N. AUERBACH AND A. YEVERECHYAHU. Tel-Aviv University, Tel-Aviv, Israel.

Resonances.

De-

We write down a set of coupled hydrodynamic equations of the Navier-Stokes type which describe the motion of two compressible, viscous nuclear fluids. The solutions of these equations give rise to giant resonances of both isoscalar and isovector type. The viscosity terms in the equations are responsible for the damping of these resonances. Within this framework we obtain expressions for the width of the resonances as a function of the mass number A, and relations between the widths and the excitation energies for various multipolarities (J = O+, I -, 2+, 3-, 4+), and isospins (T = 0, I). The A dependence of the calculated widths exhibit the experimental trends of the giant dipole and isoscalar quadrupole widths. Also, as a result of the calculation we obtain estimates of the values of viscosity coefficients in nuclei. Theory of Pion-Nucleus Scattering. F. LENZ. Laboratory for Nuclear Science and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts.

Nonstatic

A multiple scattering description of n-nucleus scattering that does not make use of the standard fixed-scatterer approximation (FSA) is presented. A generalized version of the impulse approximation is derived. This is then used to obtain an improved first-order optical potential, which is studied for pion energies around the 3-3 resonance. One of the most important features of the nonstatic description is to take into account the intermediate propagation of the interacting T-N system (d). This propagation induces a nonlocality in the optical potential. Its effect is studied for pion propagation in nuclear matter, which is found to be dominated by two collective modes of the x-nucleus system. The static description represents a well-defined limit of our Copyright All rights

(1_1!1975 by Academic Press, Inc. of reproduction in any form reserved.

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