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Di-nucleon correlations and soft dipole excitations in exotic nuclei Institute of Theoretical Physics, CAS September 24, 2010. Hiroyuki Sagawa Center for Mathematics and Physics, University of Aizu. Introduction
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Di-nucleon correlations and soft dipole excitations in exotic nuclei Institute of Theoretical Physics, CAS September 24, 2010 Hiroyuki Sagawa Center for Mathematics and Physics, University of Aizu • Introduction • BCS-BEC crossover • Three-body model and di-neutron correlations in exotic nuclei • Soft dipole excitations and three-body breakup in 6He and 11Li • Di-proton correlations in 17Ne • Summary
Pairing correlations in nuclei Coherence length of a Cooper pair: much larger than the nuclear size (note) R = 1.2 x 1401/3 = 6.23 fm (for A=140) x = 55.6 fm
Weakly interacting • fermions • Correlation in p space • (large coherence length) • Interacting • “diatomic molecules” • Correlation in r space • (small coherence length) cf. BEC of molecules in 40K M. Greiner et al., Nature 426(’04)537
BCS Crossover region
Messages from Nuclear Matter Calculations 76, 064316(2007)
16C 18C Borromian Nuclei (any two body systems are not bound, but three body system is bound)
H. Esbensen, G.F. Bertsch, K. Hencken, Phys. Rev. C56(’99)3054 Three-body model n Density-dependent delta-force r1 VWS VWS v0 ann a S2n r2 core n (note) recoil kinetic energy of the core nucleus • Hamitonian diagonalization with WS basis • Continuum can be included by solving Green’s functions • Pauli blocking is properly taken into account. Important for dipole excitation Application to 11Li, 6He
Two-particle wave functions (J=0 pairs) Hamiltonian diagonalization • Continuum: box discretization • Energy cut-off:
Application to 11Li, and 6He 11Li, 6He: Typical Borromean nuclei 11Li: (Efimov states ?) WS: adjusted to p3/2 energy in 8Li & n-9Li elastic scattering Parity-dependence to increase the s-wave component 6He: WS: adjusted to n-a elastic scattering
Two-particle density for 11Li n r1 q12 9Li r2 n Set r1=r2=r, and plot r2 as a function of r and q12 • two-peaked structure • Long tail for “di-neutron” S=0 S=0 or 1 di-neutron cigar-type)
Comparison among three nuclei 11Li 6He (p1/2)2 :59.1% (s1/2)2 :22.7% (d5/2)2 :11.5% (p3/2)2 :83.0 % (d5/2)2 :6.11 %, (p1/2)2 :4.85 % (s1/2)2 :3.04 %, (d3/2)2 :1.47 % for (p1/2)2 or(p3/2)2 for (s1/2)2
Coexistence of BCS-BEC like behaviour of Cooper Pair in 11Li Probing the behavior at several densities
: di-neutron configurations : cigar-like