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Exploring the symmetry energy and the level density parameter with the isospin effects

Paola Marini, Texas A&M University, USA
Mardi 2 mars 2010 à 10h30 - Salle des Séminaires

In this contribution we will describe two experiments performed at GANIL, in which the 4¼ multi-detector INDRA was coupled to the VAMOS spectrometer. Two fundamental physical quantities have been investigated as function of the isospin effects :

  • Isospin effects in heavy-ion collisions were explored with the aim of constraining the symmetry energy at sub-saturation density.
  • Determination of the level density parameter for Pd isotopes ranging in mass from the proton drip-line to neutron rich side of the nuclear chart.

The advent of radioactive beams, coupled to judiciously chosen targets, allows for the very first time to explore a wide range of N/Z asymmetry. The dependence of the symmetry energy term in the EOS of the square of the isospin asymmetry suggests the symmetry energy can be investigated with nuclear collisions between target and projectile combinations leading to the formation of nuclear systems very asymmetric in neutron and proton numbers. The isospin level density parameter dependence can be investigated exploring the variation of de-excitation properties of the compound nucleus when going from the proton drip line to neutron rich nuclei. Experiments performed up to now on these subjects consisted in inclusive measurements, in these experiments we aim at obtaining highly exclusive data by detecting, event by event, the projectile-like fragment and the residue, respectively, and all the associated charged particles. Preliminary results of the two experiments will be given in this presentation.