Neutron-Neutron Correlations in the Dissociation of Halo Systems: 6 He

1. Neutron-Neutron Correlations in the Dissociation of Halo Systems: 6He Group "Exotiques" LPC-Caen Collaboration LPC-CHARISSA-DEMON

2. Neutron-Neutron Correlations in the Dissociation of Halo Systems: 6He • Motivation + History • Principles of neutron-neutron interferometry • 6He breakup • Limitations – coherence, theory… • Conclusions & Perspectives

3. Two-Neutron Halo Systems  “Borromean”

4. Two-Neutron Halo Systems  n-n interaction in field of core binds the system ...

5. Two-Neutron Halo Systems  rnn Halo neutron correlations … ?

6. Halo n-n Spatial Configuration 6He “cigar” “dineutron” RNBT Collaboration – 3-body Faddeev

7. 3-body Model Calculations * : 6He = a + n +n ground state wavefunction “cigar” “dineutron” r1 =r2 = rc-nn = 3.6 fm;rnn = 4.6 fm *Hagino, Sagawa, Phys Rev C72 (2005)

8. A History of Probes … • dissociation: pcore v’s pn[Hansen] • dissociation:pnn[Ieki et al.] • very high EB dissociation:s-2n v’s s-1n[Bertsch et al.] • see also JA Tostevin (today) • 2n transfer [Oganessian et al.] • see also T Roger, N Keeley (yesterday) • radiative capture [Sauvan et al.] • dissociation:E1 strength + Rrms[Hagino, Sagawa] • Rrms charge [Mueller et al.] • ……

9. “That was the beginning, and the idea seemed so obvious to me and so elegant that I fell deeply in love with it. And, like falling in love with a woman, it is only possible if you do not know much about her, so you cannot see her faults. The faults will become apparent later, but after the love is strong enough to hold you to her." • Richard Feynman • Nobel Lecture (1965)

10. Intensity Interferometry - HBT Effect* : Source Size Correlation Function - Cnn FM Marqués et al., PLB (2000) Cnn dominated by n-n FSI*incoherent emission

11. Cnn(r,t) : r0= 3 fm ; t= 0, 100, 300*, 1000 fm/c * 5HegsG~ 0.7 MeV Group Exotiques - G. Normand et al.

12. 3-Body Breakup: “Complete Kinematics” vn1 vn2 v0 vcore Target pn-n = pn1 - pn2Erel = m(vcore- vnn)2/2

13. Intensity Interferometry - HBT Effect U. of Sydney Stellar Interferometer, Narrabri, NSW “Hanbury-Brown’s Steamroller“ D Kleppner, Physics Today, August 2008

14. Setup: Kinematically “Complete” Measurement DEMON 90 modules (NE213)  ToF & position en ~ 10% enn ~ 1% FM Marqués et al., NIMA450 (2000) + Cross-talk Rejection !!

15. n-n Separation : EMD + Cnn + Gaussian Source* * R Lednicky, VL Lyuboshits, Yad. Fiz. (1982) Event mixing – residual correlations FM Marqués et al., PLB (2000)

16. C/Pb(6He,a+n+n)X @ 30 MeV/u : Cnn + Gaussian Source * * * rnnaverage of n-n configurations of 6He breakup states Group Exotiques - G. Normand et al.

17. C/Pb(6He,a+n+n)X @ 30 MeV/nucleon 2+ 2+ (1-,… ) Group Exotiques - G. Normand et al.

18. C/Pb(6He,a+n+n)X @ 30 MeV/nucleon 2+ 2+ Ed(6He) after subtraction of uncorrelated distribution Groupe Exotiques - G. Normand et al.

19. Three-body continuum spatial correlations in 6He * *B Danilin et al., PRC69 (2004)

20. Effects of a coherent n-n source * * Yamashita et al., PRC72 (2005), NUPA735 (2004)[ Data: FMM et al. PLB (2000) ]

21. Conclusions & Perspectives • Neutron-neutron correlations … • breakup + “interferometry˝ (Cnn) as a possible tool to explore halo n-n correlations in unbound Ex/continuum • Improvements … • First step : account for coherence in emission • Ideally : realistic structure + reaction + FSI to generate pnn, Cnn,pcore, ds/dE, …

22. Pb(11Li,9Li+n+n)X @ 28 MeV/nucleon 3-body model wave function+ EMD + FSI(c-n et nn) H Esbensen et al., PRC48 (1993)

24. C/Pb(6He,a+n+n)X @ 30 MeV/nucleon Group Exotiques - G. Normand et al.

25. C/Pb(6He,a+n+n)X @240MeV/nucleon GSI/LAND – T. Aumann et al.