1. Collective modes in asymmetric nuclei
- Author
-
Morawetz, K., Fuhrmann, U., Walke, R., Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Grand Accélérateur National d'Ions Lourds (GANIL), Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Bao-An Li, W. U. Schroeder, Normandie Université (NU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Girod, Dominique
- Subjects
[PHYS.NUCL] Physics [physics]/Nuclear Theory [nucl-th] ,Nuclear Theory (nucl-th) ,Nuclear Theory ,[PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th] ,FOS: Physical sciences - Abstract
The collective motion of a finite nuclear system is investigated by numerical simulation and by linear response theory. Using a pseudo-particle simulation technique we analyze the giant resonances with a multipole decomposition scheme. We examine the energy and the damping of different giant collective modes and obtain the dependence of these quantities on the proton-neutron ratio. ...(abbreviated) Alternatively the giant collective modes in asymmetric nuclear matter are investigated within linear response theory including the collisional correlations via a dynamic relaxation time approximation. For a multicomponent system we derive a coupled dispersion relation and show that two sources of coupling appear: (i) a coupling of isoscalar and isovector modes due to the action of different mean-fields and (ii) an explicit new coupling in asymmetric matter due to collisional interaction. We show that the latter is responsible for a new mode arising besides isovector and isoscalar modes...(abbreviated) Collective motion beyond the linear regime is demonstrated for the example of large-amplitude isoscalar giant octupole excitations in finite nuclear systems. Depending on the initial conditions we observe either clear octupole modes or over-damped octupole modes which decay immediately into quadrupole ones. This dependence on initial correlations represents a behaviour beyond linear response.
- Published
- 2001