Working group on FragmentsTheory: Comparison of statistical models for fragment production

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Working group on Fragments/TheoryComparison of
statistical models for fragment production
Betty Tsang WCI 2005 Texas A M Feb 12-16, 2004
The National Superconducting Cyclotron
Laboratory _at_Michigan State University
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Resource Letters in Frontiers in Physics, AJP,
72(2004)
Going up in Ex one comes to a domain where the
nuclei produced in the reaction have time to
equilibrate and are best described with
statistical concepts.
The successful use of statistical models to
describe nuclear reactions and provide insights
to the physics of Multifragmentation is an
achievement in our field.
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Limited Goals

• To compare different statistical models for
  multifragmentation.
• 3 Bench-mark systems E/A5 MeV, r/ro1/3
• A186, Z75, N/Z1.48
• A168, Z75, N/Z1.24
• A168, Z84, N/Z1.0
• To test out different after-burners
• 2 Bench-mark systems E/A2 MeV
• A186, Z75, N/Z1.48
• A168, Z75, N/Z1.24

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Disclaimer

• The results presented here have not been
  discussed in detail with the relevant persons.
• (authors, users)

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Program codes

• I. Fragment production codes and corresponding
  users    
• 1) Statistical Multifragmentation Models
•         a.   Bougault SMM95 by Botvina et al
•         b.   Souza ISMM microcanonical by
  Souza Donangelo
• c. Tsang ISMM canonical by Das
  Gupta 
•    2)    Friedman EES by Friedman
•     3)   Raduta / Alexandru Adriana MMM by
  Radutas
• 4) Lefevre MMMC by Gross
•     5)    Regnard (LG-Caen) LGM by Gulminelli
• 6) Trautmann QSM by Stoecker
• 7) Colonna BNV in a box by Colonna
• II. After-Burner
• 1) Charity Gemini by Charity
• 2) Wada Texas AM Gemini by Wada
• 3) Durand Simon by Durand
• 4) Tsang MSU decay by Tan

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Observable used in comparisons

• ltNIMFgt
• A Z distributions
• Isotope Distributions Centroid widths
• N/Z distributions
• Isoscaling
• Isotope thermometers (Albergo temperatures)
• To test the after-burners
• Effect from primary to secondary decays

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Final
Primary
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Final
Primary
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ltNIMFgt
Common Features sequential decays reduce the
multiplicities -- Except SMM95 Similar values of
ltN_IMFgt Low values LP-Caen High values QSM
no heavy fragments Indication of larger
multiplicity with neutron-poor emitting systems ?
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A Z Distributions
Similar general trends but differ in details
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Isotope distributions
Effects of sequential decay on isoscaling
Primary (wider)
Final (narrower )
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Isoscaling in statistical models
Primary distributions show good
isoscaling A2186, Z275 A1168, Z175
WCI statistical model working group (2004)
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Effects of sequential decay on isoscaling
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Effects of Sequential decays on alpha
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BNV in a box
The isoscaling occurs over four orders of
magnitude while the range is 2 order of magnitude
for other statistical model. a(BNV) is about
factor of 10 larger.
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Temperature determined from Isotope yield
ratio(Albergo temperatures)
Not used as temperatures but test for sequential
decays from the fluctuations.
Fragment yield ratios e.g. (3He/4He)/(6Li/7Li)
(3He/4He)/(9Be/10Be) (3He/4He)/(12C/13C) (11C/12C)
/(6Li/7Li) (11C/12C)/(9Be/10Be)
7Li
Binding Energy
g.s. assumed
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Program codes

• I. Fragment production codes and corresponding
  users    
• 1) Statistical Multifragmentation Models
•         a.   Bougault SMM95 by Botvina
•         b.   Souza ISMM microcanonical by
  Souza
• c. Tsang ISMM canonical by Das
  Gupta 
•    2)    Friedman EES by Friedman
•     3)   Raduta / Alexandru Adriana MMM by
  Radutas
• 4) Lefevre MMMC by Gross
•     5)    Regnard (LG-Caen) LGM by Gulminelli
• 6) Trautmann QSM by Stoecker
• 7) BNV in a box by Colona
• II. After-Burner
• 1) Charity Gemini by Charity
• 2) Wada Texas AM Gemini by Wada
• 3) Durand Simon by Durand
• 4) Tsang MSU decay by Tan

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Summary

• Most SMM models are good for predicting gross
  features but details required fitting to data.
• Some models may not be good to reproduce
  experimental data but may be used to provide
  physics insights.
• Files and figures are available in the WCI
  strategy web site.
• Need the insights and inputs from the code owner
  and users to sort out the differences