Comparison of the isotopic distributions measured in the fragmentation of 136Xe and 124Xe projectiles with the EPAX parameterization

1
Comparison of the isotopic distributions
measured in the fragmentation of 136Xe and 124Xe
projectiles with the EPAX parameterization
Daniela Henzlova GSI-Darmstadt,
Germany NSCL-MSU, East Lansing, Michigan
2
Overview of the measured cross sections

• more than 1100 production cross sections over 4
  orders of magnitude
• broad nuclear charge range Z3(5)-56(55) for
  136Xe(124Xe)

• extensive database for comparison with
  up-to-date parameterizations
• EPAX2 - based on fragmentation reactions of
  medium to heavy-mass projectiles in relativistic
  heavy-ion collisions

3
Isotopic resolution of FRS
124Xe
136Xe
NZk, k4
136Xe Pb 1A GeV
Z50
Z54

• final fragments in broad range unambiguously
  identified

4
Overview of the isotopic distributions

• 124XePb 1 A GeV

• 136XePb 1 A GeV

5
Comparison with EPAX lower Z

• 124XePb 1 A GeV

EPAX for 124XePb

• 136XePb 1 A GeV

EPAX for 136XePb

• underestimation of production cross sections of
  lighter isotopes

6
Comparison with EPAX higher Z

• 124XePb 1 A GeV

EPAX for 124XePb

• 136XePb 1 A GeV

EPAX for 136XePb

• underestimation of cross sections of isotopes on
  the less n-rich side of the isotopic
  distributions in case of 136Xe projectile

• slightly worse agreement with data from more
  n-rich projectile

7
Comparison with EPAX2 available data
J. Friese et al., Nucl. Phys. A 553 (1993) 753c
R. Schneider, PhD thesis, TU München (1996)
Zeit. für Phys. A 348 (1994) 241
J. Reinhold et al., Phys. Rev. C 58 (1998) 247
this work

• scarce experimental data for n-rich Xe isotope
  available

8
Comparison with EPAX mean N-over-Z

• higher ltNgt/Z in the vicinity of the 136Xe
  projectile

• low values of ltNgt/Z of the residues far from both
  projectiles

9
Comparison with EPAX mass distributions

• mass yields for both systems considerably
  underestimated

10
Summary

• strong underestimation of lighter residues
  production cross sections independently of system
  isospin

• underestimation of less n-rich isotopes for
  residues in the vicinity of 136Xe projectile

• overall 136Xe data worse reproduced

• too strong loss of memory on initial N/Z

• underestimation of mass yields for both Xe
  projectiles

present data may serve to refine the EPAX
formulation