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Isotopic Composition of Residues in 124Xe and 136Xe Projectile Fragmentation

This study examines the isotopic composition of residues produced in the fragmentation of 124Xe and 136Xe projectiles, exploring their relevance for astrophysical scenarios and properties of nuclear systems under extreme conditions. The results reveal the sensitivity of isotopic distributions to initial N/Z ratio and the length of the evaporation process.

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Isotopic Composition of Residues in 124Xe and 136Xe Projectile Fragmentation

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  1. Isotopic composition of the residues produced in the fragmentation of 124Xe and 136Xe projectiles Daniela Henzlova GSI-Darmstadt, Germany NSCL-MSU, East Lansing, Michigan

  2. Introduction abrasion projectile spectator participants target spectator • properties of nuclear system under conditions of extreme temperatures and densities • relevant for astrophysical scenarios relativistic heavy-ion collisions weak isospin diffusion

  3. Introduction • evaporation -> dominant influence on the final isotopic composition R.J.Charity, Phys. Rev. C 58 (1998), 1073 • explore isotopic distributions from two systems with very different N/Z • sensitivity to the initial isotopic composition and the length of evaporation process extraction of properties of hot system?

  4. Fragment Separator (FRS) – a high-resolution magnetic spectrometer inverse kinematics in-flight identification mass identification: position in scintillators 124Xe, 136Xe @ 1AGeVc Pb dE in ionisation chamber ToF Z/ΔZ ~ 200 A/ΔA ~ 400 • high resolving power:

  5. <N>/Z in a broad nuclear charge range 136Xe • 136Xe+Pb 1 A GeV • 124Xe+Pb 1 A GeV 124Xe 136Xe Z N • <N>/Z investigated in the broad nuclear charge range • cold residues preserve memory on the initial N/Z over the whole nuclear charge range (high excitation energies) residue corridor not reached

  6. Comparison with ABRABLA – influence of the cluster emission • ABRABLA – abrasion+evaporation code • n, p, alpha emission -> too strong removal of memory on initial N/Z • implementation of cluster emission (d, t, 3He, IMF (Z>2)) memory on initial N/Z not completely removed not sufficient to reproduce <N>/Z of experimental data

  7. Excitation energy introduced in abrasion ABRABLA (abrasion+ablation) calculation 136Xe+Pb 1A GeV 124Xe+Pb 1A GeV excitation energy above 3 MeV/A introduced break-up of highly excited system

  8. Comparison with ABRABLA – influence of the thermal conditions at the freeze-out of the break-up E*=aT2 evaporation • <N>/Z of residues from 124Xe less sensitive to length of evaporation cascade • only including the nuclear break-up allows to reproduce <N>/Z of the final residues Tf=5-6 MeV and 3-4 MeV for Z>20 136Xe and 124Xe, respectively • final <N>/Z reflects the thermal conditions at the freeze-out

  9. Summary • isotopic distributions in the broad Z rangereveal sensitivity to the initial N/Z • comparison with ABRABLA: emission of complex clusters restores memory on the initial N/Z, but not sufficient to reproduce data break-up results in improved agreement with data Tf ~ 5-6 MeV for 136Xe Tf ~ 3-4 MeV for 124Xe • three stage reaction process needed • final <N>/Z reveal sensitivity to the length of an evaporation cascade following the nuclear break-up

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