Isotopically resolved residues from the fragmentation of projectiles with largely different N/Z

1. Isotopically resolved residues from the fragmentation of projectiles with largely different N/Z Daniela Henzlova for CHARMS collaboration GSI-Darmstadt, Germany (on leave from NPI Rez, Czech Republic)

2. Motivation • high excitation energies introduced in nuclear reaction -> abundant production of small fragments nuclear liquid-gas phase transition caloric curve THeLi (MeV) liquid-gas phase transition? <E0>/<A0> (MeV) J. Pochodzalla et al., Phys. Rev. Lett. 75 (1995) 1040 DPG Berlin 4.3.2005 D. Henzlova for CHARMS

3. Basic idea to determine nuclear temperature • thermally equilibrated nuclear system particles emitted by such a system carry information on the temperature methods: similarities: • slope of the kinetic energy spectra • based on thermodynamics • double isotopic ratio • focused on IMFs and light fragments • population of excited states • 3H, 3He yield ratio DPG Berlin 4.3.2005 D. Henzlova for CHARMS

4. New experimental investigation • fragmentation of 136Xe (N/Z=1.52)and 124Xe (N/Z=1.30) isotopic identification over the full nuclear charge range • alternative approach – the isospin thermometer method freeze-out evaporation final fragment N/Z N’/Z’ follow the isotopic composition of the heavy fragment during the evaporation process back in time to reconstruct its excitation energy DPG Berlin 4.3.2005 D. Henzlova for CHARMS

5. Fragment Separator (FRS), GSI Darmstadt 136Xe + Pb 1A GeV 136Xe Z N • resolving powerA/ΔA ~ 400 DPG Berlin 4.3.2005 D. Henzlova for CHARMS

6. <N>/Z in full nuclear charge range • full isotopic identification for projectiles with extreme N/Z difference obtained for the first time • difference between the final <N>/Z preserved in full nuclear charge range memory on the N/Z of the projectile preserved even at the end of evaporation DPG Berlin 4.3.2005 D. Henzlova for CHARMS

7. Evaporation as a diffusion process • mass, E* and N/Z of the nucleus changes in each evaporation step due to the emission of the nucleon or light cluster(X.Campi, J.Hüfner, Phys. Rev. C24 (1981)) excited fragment follows certain rather well defined path in the chart of nuclides 136Xe experimental data abrasion evaporation break-up • knowing the final and intermediate N/Z the excitation energy may be traced back DPG Berlin 4.3.2005 D. Henzlova for CHARMS

8. The isospin thermometer method explores the change of N/Z in evaporation process to trace back the E*~T2 of fragment entering evaporation 136Xe+Pb 1AGeV 136Xe break-up abrasion E* ~ T2 evaporation temperature at freeze-out after break-up T = 5 MeV Tf= 3MeV Tf= 4MeV Tf= 5MeV Tf= 7MeV DPG Berlin 4.3.2005 D. Henzlova for CHARMS

9. Summary • isotopic composition in the complete Z range was measured for residues from 136Xe (N/Z=1.52) and 124Xe (N/Z=1.30) projectiles • freeze-out temperature of 5 MeV in the broad Z range was deduced from the isospin thermometer method • temperature extracted using evaporation of the heavy residues is consistent with values extracted from light and IMFs DPG Berlin 4.3.2005 D. Henzlova for CHARMS