1. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 1 Nucleon-nucleon momentum correlation function (HBT) for neutron-rich nuclei Ma Yu-Gang ( 马余刚 ) Shanghai Institute of Applied Physics (SINAP) Chinese Academy of Sciences 中国科学院上海应用物理研究所 E-mail: ygma@sinr.ac.cn Tel: (021)59554780; FAX:(021)59552556

2. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 2 CONTENT of the TALK Introduction of HBT Application of n-n HBT in neutron-rich nuclei n-pOur recent work of n-p HBT in neutron-rich nuclei The influences of nuclear transport property on HBT strength Experimental proposal Conclusion

3. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 3 I. INTRODUCTION

4. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 4 HI collisions at intermediate energies Opportunity to probe the nuclear Equation Of State (EOS) Use transport theory to relate dynamics to EOS,  NN, … Problems with secondary decays Test transport theory: improvements require experimental constraints on secondary decays Need probes of the space-time properties of the emission NN collisions, compression, pre-equilibrium Breakup, expansion Secondary decays Short time scalesLong time scales

5. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 5 A Pictorial View of Micro-Bangs at RHIC Thin Pancakes Lorentz  =100 Nuclei pass thru each other < 1 fm/c Huge Stretch Transverse Expansion High Temperature (?!) The Last Epoch: Final Freezeout-- Large Volume We measure the “final” state, we are most interested in the “intermediate” state, we need to understand the “initial” state…

6. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 6 The complexity of these collisions force us to employ all tools at our disposal: Coalescence Like-particle correlations Unlike-particle correlations All such techniques measure the distribution of the final strong interaction of the various species A. Continued

7. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 7 Astronomy: Hanbury-Brown and Twiss (1950’s) － HBT photon-photon correlations can explore the angular diameter of stars and other astronomical objects. Particle physics : S.Goldhaber, G.Goldhaber, Lee and Pais (1960)  - , K-K,  -K etc. correlations can measure the spatial extent of the annihilation fireball in proton-proton and A-A reaction Nuclear physics : p-p, n-n and n-p, IMF-IMF correlation in HIC, space-time infor. Semiconductor : analogous correlations, electron-electron correl (recently) B. Continued

8. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 8 Intensity interferometry: from large scales... Star R d << R Static systems: exploring the geometry (size, R) HBT: R. Hanbury Brown, R.Q. Twiss, Phil. Mag., Ser. 7 45 (1954) 663 … to subatomic physic scales ( , K-K, , p-p, n-n, IMF-IMF, …) Fast evolving systems: 10 -23 -10 -15 sec: geometry changing in time Detectors Nuclear reaction d >> R R+V  G. Goldhaber et al., PR 120 (1960) 300

9. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 9 B. 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……

10. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 10 S. Pratt, Physical Review Letters. 53 (1984) 1219 C. Continued

11. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 11 Two-Proton correlation functions q (MeV/c) 1+R(q) p-p correlation function R(q) sensitive to the space-time properties of emitting sources Emitting Source Target Proj Detector Arrays

12. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 12 Sensitivity to space-time extent Final State Interactions (Coulomb+Nuclear) + Pauli Directional information: Shape, Lifetime Pauli exclusion principle Coulomb: Dip at q ~ 0 1+R(q) q (MeV/c) 050100 Large source Small source q (MeV/c) Nuclear: Peak at Size (S wave)

13. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 13

14. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 14 Angle-averaged correlation functions Angle-averaged Koonin-Pratt equation S(r) = source function with spherical symmetry Angle-averaging over

15. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 15 Source-sizes from angle-averaged correlations extracted from C(20 MeV/c) Gaussian sources extensively used One-parameter approach (r 0 )

16. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 16 Systematics of size measurements Problems with long lifetime proton emission Target= 197 Au Proj (A P ) r 0 (fm) V p /V beam Pre-equlibrium Long  A P =3 A P ~15 A P =40 3 He 14 N, 16 O 40 Ar

17. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 17 D. Experimental Equipment BNL AGS CERN SPS

18. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 18 RHIC PHENIX STAR D. Continue

19. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 19 D. Continue: 4  charged particle detector, neutron wall

20. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 20 II. Application of n-n HBT in neutron-rich nuclei

21. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 21 History of Exotic nuclei study Tanihata, et al., Phys. Rev. Lett, 55 (1985) 2626.

22. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 22 halo nucleus Picture of halo nucleus Neutron halo Proton halo neutron-proton halo Density Distribution of Halo Nucleus One nucleon halo Two nucleons halo Giant halo Outer nucleons Core

23. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 23 1 Glauber theory  tot lower than data at low E in 2 Semi-emprical formula Kox et al., Shen et al. 3 Nuclear transport method Y.G. Ma et al., Phys. Lett. B302 (1993) 386~389 Good fit to  tot lower at low Ein, and EOS and  nn can be extracted A. Total cross section

24. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 24 中能下 23 Al 碎裂反应实验等 @ RIBALL & RIKEN 左图 30A MeV 下 17 F, 27 P 和 23 Al 反应截 面的实验结果。可 以看出 17 F, 27 P 和 23 Al 的反应截面有着反 常的增大，有可能 存在质子晕或皮。 X.Z. Cai, H.Y. Zhang, W.Q. Shen et al., Phys. Rev. C 65 (2002) 024610 H.Y. Zhang, W.Q. Shen, et al., Nucl. Phys. A 707 (2002) 303

25. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 25 B. Parallel momentum distribution 从 29 P 单质子剥离 28 Si 动量分布 Exp. @ RIBALL Wei, Ma et al., submitted

26. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 26 neutron-neutron C. HBT study for neutron-neutron Correlation function between the two nutrons. The curve represents a calculation based on a spherical Gaussian source with radius parameter 5.3 fm

27. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 27 C. continued Systems with different level of bounding character will lead to different HBT strength.

28. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 28 C. continued HBT Exp. Results of different Two-neutron halo nuclei. E S (2n) (MeV) 6 He : 0.280 11 Li : 0.310 14 Be: 1.340 12 C(stable) : 31.841 Marques et al. PLB476, 219(2000)

29. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 29 Exotic phenomenon Larger radius Unbounded nucleons Loosely system Less separation energy per (two) nucleon (s) Total reaction cross section Narrow parallel momentum distribution Extended density distribution HBT ? C. HBT study

30. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 30 III: Our Recent Work of neutron-proton HBT for neutron-rich nuclei Phys Lett B 586, 225 (2004) Chin Phys Lett 21, 629(2004) Phys Rev C, to be submitted

31. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 31 Isospin dependent QMD Isospin-dependent Quantum Molecular Dynamics Model: N-body transportation theory model Including the most important parts for nuclear reaction at intermediate energy

32. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 32 Check of stability of IQMD

33. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 33 Firstly we reproduce the experimental results with IQMD + CRAB 14 Be + 12 C @ 35MeV/n It is obviously that the cal. results reproduce the exp. data very well.

34. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 34 The obvious different results have been obtained between the halo neutrons and normal neutrons.

35. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 35 The relationship between the binding energy per nucleon and the HBT strength in Be isotopes. There exits almost linear relationship between them!

36. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 36 More isotopes have been investigated Systematical study

37. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 37 How about the separation energy ? Just like that of binding energy per nucleon, the relationship between the HBT strength and the separation energy still exits the linear character.

38. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 38 The importance of the correct initialization in QMD

39. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 39 IV. The influences of nuclear transport property on HBT total pair momentum nuclear EOS in-medium n-n cross section impact parameter incident energy emission time

40. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 40 Ptot dependence Higher P total Stronger HBT strength Exp. Data, Gong et al Gate of the particles with higher total momentum have higher velocity, which results the shorter emission time. The stronger HBT strength indicates this tendency clearly from both Exp. and Theory.

41. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 41 EOS Soft potential Compared with Stiff potential taken in IQMD model. Nuclear matter with Stiff potential will be harder to be pressured. With the soft one the nucleons will be emitted easier. The Cal. Results display this tendency

42. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 42  nn dependence Larger  nn leads to larger nucleon- nucleon scattering probability, which induces some nucleon emission earlier. Consequently, this will lead to larger HBT strength.

43. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 43 Impact parameter dependence Nuclear collisions in different impact parameters: The head-on collision leads to the hotter nuclear matter which make nucleon emission earlier, which is equivalent to the compact emission source; In contrary, the peripheral is a cool emitter, the emission time is later and the corresponding source becomes loose. The above reason will result that, in our calculation, the HBT strength decreases with increasing impact parameter. This is also consistent with the experimental observation!

44. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 44 Incident energy dependence

45. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 45 V : Experimental proposal for n-p HBT measurement @ RIBLL LASCAR

46. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 46 VI. Conclusion HBT approach has been applied systematically to the research of neutron- rich nuclei. It was revealed for the first time that there exits strong dependence for neutron- proton HBT strength to the separation energy and the binding energy. HBT approach is suitable to investigate the collision transport properties

47. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 47 Thank you for your attention!

48. 马余刚第十次全国核结构讨论会 2004-7-25/28, 贵阳 48 Proton emission in HIC at intermediate energies Fast emissions Pre-equilibrium Long lifetime emissions Evaporation, secondary decays Secondary decays: easily Strong contribution to S(r) Directional correlations dominated by pre-equilibrium emission – reduced sensitivity to long-lifetime scales.