Energy Dependence of the Isotopic Composition in Nuclear Fragmentation

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Energy Dependence of the Isotopic Composition in
Nuclear Fragmentation

• S. Yennello, D. Shetty, M. Veselsky, E. Martin,
  A. Keksis, G. Souliotis and D. Rowland
• Texas AM University
• Cyclotron Institute

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Two component liquid
Single component liquid
Two component liquid
Free n/p ratio t/3He ratio N/Zfragments
Possible signatures
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Neutron content as a function of fragment size
for N/Z 1.2 to 2 DLi 11.5 DSi 2.6
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Veselsky, Phys. Rev. C 62, 064613 (2000).
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Veselsky, Phys. Rev. C 62, 064613 (2000).
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28Si 112,124Sn
Veselsky,Phys Lett B 497,1(2001)
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Ratio of isotopic yields58Ni, 58Fe 58Ni, 58Fe
30 Mev/nuc
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Scaling factor
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Relative free neutron and proton densities
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Scaling factor at 30,40,47 MeV/nuc
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neutron and proton densities at 30,40,47 MeV/nuc
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Energy dependence of the scaling parameter a
58Fe 58Fe / 58Ni 58Ni
30 MeV 40 MeV 47 MeV
a 0.372 0.269 0.23
b -0.395 -0.372 -0.32
.
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Canonical model predictions (SMM-McGill)
Temperature (left panel) and density (right
panel) dependence of the scaling parameter a.
Tsang PRC64, 054615 (2002)
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Botvina IsoscalingR21 C exp(aA b(N-Z)
a D(mn mp)/2T
b D(mn - mp)/2T
28Si 112,124Sn
30 MeV/nuc
50 MeV/nuc
b 0.2370.038
b 0.1860.017
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Botvina IsoscalingR21 C exp(aA b(N-Z)
28Si 112,124Sn 50 MeV/nuc
E (MeV) b
3 0.31
4 0.20
5 0.19
6 0.18
7 0.17
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Summary

• The enhancement in free neutrons of neutron-rich
  systems is greater at lower energies.
• Isoscaling in 58Ni, 58Fe 58Ni, 58Fe
• 3H/3He in 28Si 112Sn, 124Sn
• Isoscaling in 28Si 112Sn, 124Sn

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Theory
Bao An Li PRL 2000
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Summary

• The enhancement in free neutrons of neutron-rich
  systems is greater at lower energies.
• Isoscaling in 58Ni, 58Fe 58Ni, 58Fe
• 3H/3He in 28Si 112Sn, 124Sn
• Isoscaling in 28Si 112Sn, 124Sn
• Theoretical comparisons are in progress.

This work was supported in part by the Department
of Energy and the Robert A Welch Foundation