Two-component (neutron/proton) statistical description of low-energy heavy-ion reactions

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Two-component (neutron/proton) statistical description of low-energy heavy-ion reactions. E. Btk & M. Veselsk Institute of Physics, Slovak Academy of Sciences 84511 Bratislava, Slovakia. Introduction Deep-inelastic effect of neutron/proton composition at periphery - PowerPoint PPT Presentation

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  • Two-component (neutron/proton)statistical descriptionof low-energy heavy-ion reactionsE. Btk & M. Veselsk

    Institute of Physics, Slovak Academy of Sciences84511 Bratislava, Slovakia

    EURISOL workshop, ECT* Trento, 16-20 Jan. 2006

  • IntroductionDeep-inelastic effect of neutron/proton composition at peripheryTime scales of the processesPossible playground for pre-equilibrium

    EURISOL workshop, ECT* Trento, 16-20 Jan. 2006

  • EURISOL workshop, ECT* Trento, 16-20 Jan. 2006

  • Experiments: 86Kr on 64Ni, 112,124Sn at 25 A MeV:- observed excess of exp. yields of neutron-rich nuclei with Z=32-34 (sometimes in wider range)explainable within DIT, but better fit with scaled transfer probabilities

    (for details: Veselsk, Souliotis: Nucl. Phys. A765 (2006), 252)

    EURISOL workshop, ECT* Trento, 16-20 Jan. 2006

  • Standard DIT ( Tassan-Got & Stefan, NPA 524 (1991) )86Kr + 64Ni at 25 AMeVSolid - GEMINI, dash-SMM

    EURISOL workshop, ECT* Trento, 16-20 Jan. 2006

  • Correlation of skin thickness to isovector chemical potential(V. Kolomietz et al, PRC 64(2001)024315, extended Thomas-Fermi calculation)

    - Rn-Rp determines the difference of N/Z at (Rn+Rp)/2 ( surface ) from the bulk N/Z, correlates to isovector chemical potential - DIT (T-G) : macroscopic formula for Rn-Rp used, values unrealistically large, but bulk N/Z dynamics described well

    EURISOL workshop, ECT* Trento, 16-20 Jan. 2006

  • Modified DIT (Veselsk & Souliotis: Nucl.Phys. A765 (2006)):phenomenological correction, effect of shell structure on nuclear periphery (assuming Rn-Rp vs. n-p correlation) and thus on transfer probabilities estimated as:where S... = S...exp - S...ld , is a free parameter ( = 0.53 determined as optimal value), s > 0 fm (only non-overlapping configurations considered)

    EURISOL workshop, ECT* Trento, 16-20 Jan. 2006

  • Modified DIT (Veselsk & Souliotis: Nucl. Phys. A765)86Kr + 64Ni at 25 AMeVsolid - GEMINI, dash -SMM

    EURISOL workshop, ECT* Trento, 16-20 Jan. 2006

  • DIT Conclusions - 86Kr + 64Ni, 112,124Sn at 25 AMeV

    - a microscopic correction to macroscopic DIT describes the effect of isospin asymmetry at nuclear periphery

    - inversion of the bulk isospin flow due to microscopic structure at nuclear periphery

    - consistent parameters for all reactions

    - SMM reproduces the yields of n-rich species well while overestimating the yields of -stable isotopes close to the projectile

    - GEMINI typically overestimates the width of mass distributions

    - for p-rich target 112Sn stronger Coulomb interaction supresses the effect of isospin asymmetry at nuclear periphery at s < 1 fm

    EURISOL workshop, ECT* Trento, 16-20 Jan. 2006

  • Time scale (example):

    EURISOL workshop, ECT* Trento, 16-20 Jan. 2006

  • EURISOL workshop, ECT* Trento, 16-20 Jan. 2006

  • EURISOL workshop, ECT* Trento, 16-20 Jan. 2006

  • Pre-equilibrium (exciton model master eq.):initial excited zone should follow the Z/N composition of overlapping region importance of surfacesinitial number of excitons can be estimated from the overlap of nuclei in momentum space

    at higher energies and

    at lower energies (below 5 or 10 A MeV above Coulomb)

    EURISOL workshop, ECT* Trento, 16-20 Jan. 2006

  • Inclusion of spin - HIC:(Btk: Fizika B12 (2003), 11)

    EURISOL workshop, ECT* Trento, 16-20 Jan. 2006

  • Pre-equilibrium exciton model suitable instrument to describe the effect of the neutron/proton composition of the initial overlapping region. Features: - model estimates of n0 - spin- and energy- distributions of initial phase - spin couplings as necessary - includes also equilibrated (CN) emission

    EURISOL workshop, ECT* Trento, 16-20 Jan. 2006

  • Thank you

    EURISOL workshop, ECT* Trento, 16-20 Jan. 2006

  • EURISOL workshop, ECT* Trento, 16-20 Jan. 2006

  • Experiments at fragment separator MARS ( Cyclotron Lab, Texas A&M University ).

    EURISOL workshop, ECT* Trento, 16-20 Jan. 2006

  • 86Kr + 124Sn at 25 AMeVStandard DIT ( Tassan-Got )solid - GEMINI, dash -SMM

    EURISOL workshop, ECT* Trento, 16-20 Jan. 2006

  • 86Kr + 124Sn at 25 AMeVModified DIT (nucl-th/0507026):solid - GEMINI, dash -SMM

    EURISOL workshop, ECT* Trento, 16-20 Jan. 2006

  • 86Kr + 112Sn at 25 AMeVStandard DIT ( Tassan-Got )solid - GEMINI, dash -SMM

    EURISOL workshop, ECT* Trento, 16-20 Jan. 2006

  • 86Kr + 112Sn at 25 AMeVModified DIT (nucl-th/0507026):solid - GEMINI, dash -SMMDash-dotted - SMM, s > 0.8 fm

    EURISOL workshop, ECT* Trento, 16-20 Jan. 2006

  • 86Kr + 64Ni at 25 AMeV, Exp. vs. Sim. vs Sim. ICF-only

    EURISOL workshop, ECT* Trento, 16-20 Jan. 2006

  • Isoscaling in nuclear processes M.B. Tsang et al., PRL 86(2001)5023G. Souliotis et al., PRC 68(2003)24605 M. Veselsk et al., PRC 69(2004)44607

    EURISOL workshop, ECT* Trento, 16-20 Jan. 2006

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