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In-Medium Cluster Binding Energies and Mott Points in Low Density Nuclear Matter

Clustering and Medium Effects in Low Density Nuclear Matter. In-Medium Cluster Binding Energies and Mott Points in Low Density Nuclear Matter. K. Hagel SSNHIC 2014 Trento , Italy 8-Apr-2014. Outline. Experimental Setup Clusterization and observables in low density nuclear matter.

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In-Medium Cluster Binding Energies and Mott Points in Low Density Nuclear Matter

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  1. Clustering and Medium Effects in Low Density Nuclear Matter In-Medium Cluster Binding Energies and Mott Points in Low Density Nuclear Matter K. Hagel SSNHIC 2014 Trento, Italy 8-Apr-2014

  2. Outline • Experimental Setup • Clusterization and observables in low density nuclear matter. • Clusterization of alpha conjugate nuclei • Summary

  3. 35 MeV/u 28Si + 28Si Beam Energy: 47 MeV/u Reactions:40Ar + 112,124Sn 35 MeV/u 40Ca + 181Ta, Ca, C Cyclotron Institute, Texas A & M University

  4. 14 Concentric Rings 3.6-167 degrees Silicon Coverage Neutron Ball Beam Energy: 47 MeV/u Reactions: 40Ar + 112,124Sn 35 MeV/u 28Si + 28Si 35 MeV/u 40Ca + 181Ta, Ca, C NIMROD beam S. Wuenschelet al., Nucl. Instrum. Methods. A604, 578–583 (2009).

  5. Low Density Nuclear Matter • Systems studied • 47 MeV/u 40Ar + 112,124Sn • 35 MeV/u 40Ca + 181Ta (preliminary data) • Use NIMROD as a violence filter • Take 30% most violent collisions • Use spectra from 40o ring • Most of yield from intermediate velocity source • Coalescence analysis to extract densities and temperatures • Equilibrium constants • Mott points • Symmetry energy

  6. Coalescence Parameters tavg, fm/c vsurf, cm/ns PRC 72 (2005) 024603

  7. Temperatures and Densities • Recall vsurfvs time calculation • System starts hot • As it cools, it expands 47 MeV/u 40Ar + 112Sn

  8. Equilibrium constants from α-particles model predictions • Many tests of EOS are done using mass fractions and various calculations include various different competing species. • If any relevant species are not included, mass fractions are not accurate. • Equilibrium constants should be independent of proton fraction and choice of competing species. • Models converge at lowest densities, but are significantly below data • Lattimer & Swesty with K=180, 220 show best agreement with data • QSM with p-dependent in-medium binding energy shifts PRL 108 (2012) 172701.

  9. Density dependent binding energies • From Albergo, recall that • Invert to calculate binding energies • Entropy mixing term PRL 108(2012) 062702

  10. Symmetry energy S. Typelet al., Phys. Rev. C 81, 015803 (2010). • Symmetry Free Energy • T is changing as ρ increases • Isotherms of QS calculation that includes in-medium modifications to cluster binding energies • Entropy calculation (QS approach) • Symmetry energy (Esym = Fsym + T∙Ssym) • quasiparticle mean-field approach (RMF without clusters) does not agree with the data PRC 85, 064618 (2012).

  11. Alpha clustering in nuclei • Ikeda diagram (K. Ikeda, N. Takigawa, and H. Horiuchi, Prog. Theor. Phys. Suppl. Extra Number, 464, 1968.) • Clusterization of low density nuclear matter in collisions of alpha conjugate nuclei • Role of clusterization in dynamics and disassembly. Estimated limit N = 10α for self-conjugate nuclei(Yamada PRC 69, 024309) Data Taken 10, 25, 35 MeV/u

  12. Alpha-like multiplicities • Large number of events with significant alpha conjugate mass for all systems

  13. Vparallelvs Amax • Observe mostly PLF near beam velocity for low E* • More neck (4-7 cm/ns) emission of α-like fragments with increasing E*

  14. Origin of alpha conjugate clusters • Heavy partner is near beam velocity • alphas originate from neck emission

  15. Source Frame study of Origin of clusters

  16. Origin of alpha conjugate clusters(continued)

  17. Source Frame Origin of clusters(continued)

  18. Summary • Clusterization in low density nuclear matter • In medium effects important to describe data • Equilibrium constants • EOS Implications • Density dependence of Mott points • Symmetry Free energy -> Symmetry Energy • Clusterization of alpha conjugate nuclei • Large production of α-like nuclei • Ca + Ca • Ca + Ta • Ca + C • Neck emission of alphas important

  19. Outlook and near future • Low density nuclear matter • We have a set of 35 MeV/u 40Ca+181Ta and 28Si+181Ta • Disassembly of alpha conjugate nuclei • Analysis on presented systems continues • Have Si + C, Si + Ta (almost calibrated) and Ca + Si

  20. Collaborators J. B. Natowitz, K. Schmidt, K. Hagel, R. Wada, S. Wuenschel, E. J. Kim, M. Barbui, G. Giuliani, L. Qin, S. Shlomo, A. Bonasera, G. Röpke, S. Typel, Z. Chen, M. Huang, J. Wang, H. Zheng, S. Kowalski, M. R. D. Rodrigues, D. Fabris, M. Lunardon, S. Moretto, G. Nebbia, S. Pesente, V. Rizzi, G. Viesti, M. Cinausero, G. Prete, T. Keutgen, Y. El Masri, Z. Majka, and Y. G. Ma

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