Darmstadt 2008 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 20: Physik mit schweren Ionen

HK 20.1: Group Report

Tuesday, March 11, 2008, 08:30–09:00, 2E

N/Z Dependence of projectile fragmentation — •Wolfgang Trautmann for the ALADiN2000 collaboration — GSI Darmstadt, Germany

The N/Z dependence of projectile fragmentation at relativistic energies has been studied in a recent experiment at the GSI laboratory with the ALADiN forward spectrometer coupled to the LAND neutron detector. Besides a primary beam of ¹²⁴Sn, also secondary beams of ¹²⁴La and ¹⁰⁷Sn delivered by the FRS fragment separator have been used in order to extend the range of isotopic compositions of the produced spectator sources.

The presently ongoing analyses of the measured isotope yields focus on isoscaling and its relation to the symmetry-energy term used for the fragment description at freeze-out and on the derivation of freeze-out temperatures which are found to be independent of the isotopic composition of the studied systems. The latter result is of particular interest because it favours a concept of phase-space driven expansion over that of a Coulomb-driven expansion¹ derived from the predictions of finite-temperature Hartree-Fock calculations.

¹ J.B. Natowitz et al., Phys. Rev. C 65 (2002) 034618