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Nucleon-Nucleon momentum correlation functions induced by the radioactive beams Yu-Gang Ma

Nucleon-Nucleon momentum correlation functions induced by the radioactive beams Yu-Gang Ma Shanghai Institute of Applied Physics (SINAP, CAS) Introduction Our results: nn, np, pp vs Ebind, Esep? Halo nuclei? conclusions.

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Nucleon-Nucleon momentum correlation functions induced by the radioactive beams Yu-Gang Ma

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  1. Nucleon-Nucleon momentum correlation functions induced by the radioactive beams • Yu-Gang Ma • Shanghai Institute of Applied Physics (SINAP, CAS) • Introduction • Our results: nn, np, pp vs Ebind, Esep? Halo nuclei? • conclusions 18th Few Body Conference, 2006, Santos, Brazil

  2.  weak correlation function 11Li (+ 208Pb) -> 9Li + n + n (+208Pb) Ieki et al., PRL70, 730 (1993) Our work will focus on the systematic studies on nucleon-nucleon correlation function for light nuclei! 18th Few Body Conference, 2006, Santos, Brazil

  3. Two-Proton correlation functions Detector Arrays p-p correlation 1+R(q) function Target Emitting Source Proj q (MeV/c) Final State Interaction (Coulomb + Nuclear: s-wave peak) + Pauli R(q) sensitive to the space-time properties of emitting sources 18th Few Body Conference, 2006, Santos, Brazil

  4. Intensity interferometry: from large scales ... HBT: R. Hanbury Brown, R.Q. Twiss, Phil. Mag., Ser. 7 45 (1954) 663 R d << R Static systems: exploring the geometry (size, R) Star … to subatomic physic scales (p-p, K-K, g-g, p-p, n-n, IMF-IMF, …) G. Goldhaber et al., PR 120 (1960) 300 Detectors Nuclear reaction R+Vt d >> R Fast evolving systems: 10-23-10-15 sec: geometry changing in time 18th Few Body Conference, 2006, Santos, Brazil

  5. Theoretical Calculation formula of two particles correlation In particular, the geometry of a collision is not a scale model of imaging a star. But for HBT…… 18th Few Body Conference, 2006, Santos, Brazil

  6. Source-sizes from angle-averaged correlations Gaussian sources extensively used One-parameter approach (r0) extracted from C(20 MeV/c) 18th Few Body Conference, 2006, Santos, Brazil

  7. HI collisions at intermediate energies Secondary decays NN collisions, compression, pre-equilibrium Breakup, expansion Short time scales Long time scales • Need probes of the space-time properties of the emission • Transport theory is a tool to treat space-time evolution of nucleonic system, it is a good method to exlore the nucleon-nucleon correlation function. • Use transport theory to relate dynamics to EOS, sNN, … 18th Few Body Conference, 2006, Santos, Brazil

  8. S. Pratt, Physical Review Letters. 53 (1984) 1219 18th Few Body Conference, 2006, Santos, Brazil

  9. Our results • stability check • Fits to the data (n-n correl. function) • Cp-n vs Ebinding • Cp-h vs Esep • Cp-p vs proton halo? • EOS, Sigma_nn etc Y.B. Wei, YGM et al., Phys Lett B 586, 225 (2004) Y.B. Wei, YGM et al., J Phys G 30, 2019 (2004) YGM et al., Phys. Rev. C 73, 014604 (2006) 18th Few Body Conference, 2006, Santos, Brazil

  10. QMD Isospin-dependent Quantum Molecular Dynamics Model: N-body transportation theory model Including the most important parts for nuclear reaction at intermediate energy Nuclear mean field: Nucleon-nucleon collision and Pauli blocking etc are considered .Fragment Recognition, a naive coalescence model ΔR3.5fm; ΔP300MeV/c 18th Few Body Conference, 2006, Santos, Brazil

  11. Check of stability of IQMD 18th Few Body Conference, 2006, Santos, Brazil

  12. Firstly we reproduce the experimental results of two halo neutrons for 14Be +12C @ 35MeV/n: The reaction channel: 14Be(+12C)-> 12Be + n + n (+12C) It is obviously that the cal. results reproduce the exp. data very well. Y.B. Wei, YGM et al., Phys. Lett. B 586, 225 (2004) Data: Marques et al., PLB 476, 219 (2000) 18th Few Body Conference, 2006, Santos, Brazil

  13. Data: Ieki et al., PRL70, 730 (1993) 11Li (+ 208Pb) -> 9Li + n + n (+208Pb) @ 28MeV/u The obvious different results were obtained between 2 halo neutrons (solid line) and 2 core neutrons (dash line).  Large space extension low C(q) 18th Few Body Conference, 2006, Santos, Brazil

  14. Systematical study: n-p correlation  Ebinding 11-14B (N,C,Li) + C  xn + xp + … @ 800MeV/u 18th Few Body Conference, 2006, Santos, Brazil

  15. How about the separation energy ? In model, we can also explore the correltaion between proton and the most outside neutron (Cph), see what happens? This correlation should reveal the extent of single-neutron separation. Just like that of binding energy per nucleon, the relationship between the HBT strength Cph and the separation energy still exits monotonic character. 18th Few Body Conference, 2006, Santos, Brazil

  16. A new criterion of halo nuclei? Z. Ren et al., PRC (96) 18th Few Body Conference, 2006, Santos, Brazil

  17. Density distribution and pp HBT 18th Few Body Conference, 2006, Santos, Brazil

  18. A new criterion of halo nuclei? no halo nuclei no halo nuclei If two-proton halo structure is assumed The similar behavior is expected for double-neutron halo nuclei. 18th Few Body Conference, 2006, Santos, Brazil

  19. Conclusions • Experimental two halo neutrons correlation function (11Li, 14 Be) can be well fitted by the transport model: QMD • n-p correlation function depends on the binding energy of the system. More close binding system, the stronger np correlation. • P-halo n correlation function depends on the single neutron separation energy. However, difficult accessible in the experiment. • p-p correlation function is useful to search for proton-halo nuclei. Weak correlation is expected for 2p halo nuclei. • Systematic experiment should be done in near future. 18th Few Body Conference, 2006, Santos, Brazil

  20. The influences of nuclear transport property on HBTtotal pair momentum nuclear EOSin-medium n-n cross sectionimpact parameterincident energy emission time YGM et al., Phys. Rev. C 73, 014604 (2005) 18th Few Body Conference, 2006, Santos, Brazil

  21. Total pair momentum dependence 18th Few Body Conference, 2006, Santos, Brazil

  22. In-medium cross section dependence 18th Few Body Conference, 2006, Santos, Brazil

  23. Impact parameter dependence 18th Few Body Conference, 2006, Santos, Brazil

  24. 18th Few Body Conference, 2006, Santos, Brazil

  25. Emission time & evolution time • in low Ptot, neutron and proton has a similar emission rate; • in higher Ptot, neutron has earlier emission time; • Higher Ptot. Earlier Temission nucleon-nucleon correlation function is stronger in earlier evolution time 18th Few Body Conference, 2006, Santos, Brazil

  26. Conclusions • Experimental two halo neutrons correlation function (11Li, 14 Be) can be well fitted by the transport model: QMD • n-p correlation function depends on the binding energy of the system. More close binding system, the stronger np correlation. • P-halo n correlation function depends on the single neutron separation energy. However, difficult accessible in the experiment. • p-p correlation function is useful to search for proton-halo nuclei. Weak correlation is expected for 2p halo nuclei. • Systematic experiment should be done in near future. 18th Few Body Conference, 2006, Santos, Brazil

  27. Thanks for your attention! 18th Few Body Conference, 2006, Santos, Brazil

  28. Systems with different binding character leads to different HBT strength and shape. 18th Few Body Conference, 2006, Santos, Brazil

  29. Sensitivity to space-time extent • Coulomb: • Dip at q ~ 0 Final State Interactions (Coulomb+Nuclear) + Pauli • Nuclear: • Peak at (S wave) Small source 1+R(q) • Pauli exclusion principle Size q (MeV/c) Large source 0 50 100 Directional information: Shape, Lifetime q (MeV/c) 18th Few Body Conference, 2006, Santos, Brazil

  30. In the QMD model, we can choose the random initialization or a fixed Stable Initialization. What is the difference on the HBT results? 18th Few Body Conference, 2006, Santos, Brazil

  31. 18th Few Body Conference, 2006, Santos, Brazil

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