36 research outputs found
Nuclear Attenuation of high energy two-hadron system in the string model
Nuclear attenuation of the two-hadron system is considered in the string
model. The two-scale model and its improved version with two different choices
of constituent formation time and sets of parameters obtained earlier for the
single hadron attenuation, are used to describe available experimental data for
the -dependence of subleading hadron, whereas satisfactory agreement with
the experimental data has been observed. A model prediction for
-dependence of the nuclear attenuation of the two-hadron system is also
presented.Comment: 8 page
Quasielastic Electron Scattering from Nuclei: Random-Phase vs. Ring Approximations
We investigate the extent to which the nuclear transverse response to
electron scattering in the quasielastic region, evaluated in the random-phase
approximation can be described by ring approximation calculations. Different
effective interactions based on a standard model of the type g'+V_pi+V_rho are
employed. For each momentum transfer, we have obtained the value of g'_0
permitting the ring response to match the position of the peak and/or the
non-energy weighted sum rule provided by the random-phase approach has been
obtained. It is found that, in general, it is not possible to reproduce both
magnitudes simultaneously for a given g'_0 value.Comment: 7 pages, 4 Postscript figures, to appear in Physical Review
Caloric Curves and Nuclear Expansion
Nuclear caloric curves have been analyzed using an expanding Fermi gas
hypothesis to extract average nuclear densities. In this approach the observed
flattening of the caloric curves reflects progressively increasing expansion
with increasing excitation energy. This expansion results in a corresponding
decrease in the density and Fermi energy of the excited system. For nuclei of
medium to heavy mass apparent densities ~ 0.4 rho_0 are reached at the higher
excitation energies.Comment: 4 pages, 3 figure
Sequential Decay Distortion of Goldhaber Model Widths for Spectator Fragments
Momentum widths of the primary fragments and observed final fragments have
been investigated within the framework of an Antisymmetrized Molecular Dynamics
transport model code (AMD-V) with a sequential decay afterburner (GEMINI). It
is found that the secondary evaporation effects cause the values of a reduced
momentum width, , derived from momentum widths of the final fragments
to be significantly less than those appropriate to the primary fragment but
close to those observed in many experiments. Therefore, a new interpretation
for experiemental momentum widths of projectile-like fragments is presented.Comment: 4 pages, 3 figs. Accepted for publication in Phys. Rev. C as a Rapid
Communicatio
Sequential Decay Distortion of Goldhaber Model Widths for Spectator Fragments
Momentum widths of the primary fragments and observed final fragments have
been investigated within the framework of an Antisymmetrized Molecular Dynamics
transport model code (AMD-V) with a sequential decay afterburner (GEMINI). It
is found that the secondary evaporation effects cause the values of a reduced
momentum width, , derived from momentum widths of the final fragments
to be significantly less than those appropriate to the primary fragment but
close to those observed in many experiments. Therefore, a new interpretation
for experiemental momentum widths of projectile-like fragments is presented.Comment: 4 pages, 3 figs. Accepted for publication in Phys. Rev. C as a Rapid
Communicatio
Algumas propriedades fĂsicas e hĂdricas de trĂȘs solos na Chapada do Apodi, RN, cultivados com melĂŁo
DinĂąmica fĂsico-hĂdrica de uma toposseqĂŒĂȘncia de solos sob Savana Florestada (CerradĂŁo) em Assis, SP
Recommended from our members
delta. -nucleus interactions. CTP No. 887
The theoretical description of pion-nucleus interactions, specifically in the intermediate-energy region dominated ..delta..-excitation, is discussed. Attention is focused on the interaction with and propagation through the nucleus of pions and ..delta..'s. The approach followed basically consists of viewing the ..delta..-nucleus system, formed by pion excitation of a nucleon, as a doorway for the pion-nucleus reaction. Analysis of the interacting ..delta..-nucleus system then leads to new dynamical information summarized in a complex ..delta..-nucleus interaction potential. The associated nuclear medium corrections to ..delta.. propagation, related in more conventional language to higher-order corrections in the pion optical potential, are so large as to demand consideration in quantitative studies of nuclear structure with pions. After a discussion of the basic scale parameters characterizing intermediate-energy pion-nucleus interactions, the author discusses the theoretical framework and the extraction of ..delta.. interaction parameters from inclusive pion-nucleus cross sections. More detailed tests of the picture, such as elastic scattering angular distributions, are then discussed. Finally, some implications for intermediate-energy photoreactions are outlined. 11 figures. (RWR