2017 Impact factor 2.799
Hadrons and Nuclei

Eur. Phys. J. A 9, 327-343

Stability and instability of a hot and dilute nuclear droplet

I. Adiabatic isoscalar modes

W. Nörenberg1,2 - G. Papp1,3 - P. Rozmej1,4

1 Gesellschaft für Schwerionenforschung, D-64291 Darmstadt, Germany
2 Institut für Kernphysik, Technische Universität Darmstadt, D-64289 Darmstadt, Germany
3 Institut für Theoretische Physik, Universität Heidelberg, D-69120 Heidelberg, Germany
4 Instytut Fizyki, Uniwersytet Marii Curie-Sk\lodowskiej, Pl-20031 Lublin, Poland

Received: 4 September 2000
Communicated by P. Schuck

Abstract
The diabatic approach to dissipative collective nuclear motion is reformulated in the local-density approximation in order to treat the normal modes of a spherical nuclear droplet analytically. In a first application the adiabatic isoscalar modes are studied and results for the eigenvalues of compressional (bulk) and pure surface modes are presented as function of density and temperature inside the droplet, as well as for different mass numbers and for soft and stiff equations of state. We find that the region of bulk instabilities (spinodal regime) is substantially smaller for nuclear droplets than for infinite nuclear matter. For small densities below 30% of normal nuclear matter density and for temperatures below 5 MeV all relevant bulk modes become unstable with similar growth rates. The surface modes have a larger spinodal region, reaching out to densities and temperatures way beyond the spinodal line for bulk instabilities. Essential experimental features of multifragmentation, like fragmentation temperatures and fragment-mass distributions (in particular the power-law behavior) are consistent with the instability properties of an expanding nuclear droplet, and hence with a dynamical fragmentation process within the spinodal regime of bulk and surface modes (spinodal decomposition).

PACS
21.60.Ev Collective models - 21.65.+f Nuclear matter - 25.70.Mn Projectile and target fragmentation


Copyright Società Italiana di Fisica, Springer-Verlag 2000