1 / 39

Sonja Orrigo

Sonja Orrigo. Correlation effects and continuum spectroscopy in light exotic nuclei. Unbound Nuclei Workshop, Pisa, Italy, November 3-5, 2008. Contents. Physical scenario: light exotic nuclei Correlations effects and continuum spectroscopy DCP correlations: Fano resonances

gerik
Télécharger la présentation

Sonja Orrigo

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Sonja Orrigo Correlation effects and continuum spectroscopy in light exotic nuclei Unbound Nuclei Workshop, Pisa, Italy, November 3-5, 2008

  2. Contents • Physical scenario: light exotic nuclei • Correlations effects and continuum spectroscopy • DCP correlations: Fano resonances • Experimental results on 11Be and 15C via CEX reactions • Pairing correlations in the continuum • Transfer reactions to unbound states: 9Li(d,p)10Li • Summary and conclusions

  3. Why correlation effects in light exotic nuclei? Peculiar conditions: • Large charge asymmetry • Weak binding of valence n • Proximity of s.p. continuum isovector interaction low density (halos) open quantum systems • Dissolution of shell structures • Influence of correlation dynamics light n-rich nuclei

  4. Continuum spectroscopy of light exotic nuclei • Two topics: • 15C: weakly-bound Sn = 1218 keV • effects due to the DCP correlation dynamics Fano Resonances • 10Li: n-unbound by 25 keV • effects due to pairing correlations • continuum spectroscopy by one-neutron transfer s.p. excitations • Dynamical Core Polarization • (DCP) correlations • Pairing correlations • Important to investigate their effects in the low-energy continuum

  5. Contents • Physical scenario: light exotic nuclei • Correlations effects and continuum spectroscopy • DCP correlations: Fano resonances • Experimental results on 11Be and 15C via CEX reactions • Pairing correlations in the continuum • Transfer reactions to unbound states: 9Li(d,p)10Li • Summary and conclusions

  6. Fano Resonances General phenomenon observed in many different areas of physics Atomic physics • H.Feshbach, Ann. of Phys.5 p. 357 (1958), Ann. of Phys.19 p. 287 (1962), Ann. of Phys. 43 p. 410 (1967) • F.H.Mies, Phys. Rev.175 p. 164 (1968) • A.F.Starace, Phys. Rev. B5 p. 1773 (1972) • A.K.Bhatia and A.Temkin, Phys. Rev. A29 p. 1895 (1984) • J.P.Connerade and A.M.Lane, Rep. on Progr. in Phys.51 p. 1439 (1988) Solid-state physics • S.Glutsch, Phys. Rev. B 66 p. 075310 (2002) Hadron physics N.E.Ligterink, PiN Newslett.16 p. 400 nucl-th/0203054 (2002) Nuclear physics G.Baur and H.Lenske, Nucl. Phys. A282 p. 201 (1977) Fano Resonances are investigated as a new continuum excitation mode in exotic nuclei

  7. Fano interference Fano interference quantum-mechanical interaction between discrete and continuous configurations asymmetric line shape • Originally detected in atomic spectra • 1960’s, Fano: first model for atomic states excited in theinelastic scattering e--atoms Typical for interacting many-body systems at all scales !

  8. Fano Resonances in nuclear physics Bound States Embedded in the Continuum (BSEC) • BSEC: narrow resonances in the continuum (Ex > Sn) • DCP model: BSEC as quasi-bound core-excited configurations • Experimental signature of the DCP correlations G.Baur and H.Lenske, Nucl. Phys. A 282(1977)201; H.Lenske et al., Jour. Progr. Part. Nucl. Phys.46(2001)187 • Predicted theoretically by Mahaux and Weidenmüller (1969) • C.Mahaux and H.A.Weidenmüller, Shell Model Approach to Nuclear Reactions, North-Holland, Amsterdam (1969) • 1st observed BSEC (1980): 13C (stable), Ex = 7.677 MeV (Jp = 3/2+) • H.Fuchs et al., Nucl. Phys. A 343(1980)133 And in exotic nuclei?

  9. In exotic nuclei • n-dripline nuclei: easily polarizable core BSEC at low-energy • C-isotopes: presence of low-energy 2+ core states good candidates • Importance of a systematic study H. Lenske, from HFB & QRPA calculations

  10. Fano Resonances in exotic nuclei 35 30 25 20 15 10 5 0 8.50 Single particle regime qlab = 14°, 55 keV/ch Counts 0.77 7.30 qL=8° 109 keV/ch Counts 8.50* 0.77* DCP regime 8.50 7.30 6.77 8.50* ]6.4 g.s.* 7.30* g.s. 15C Excitation energy [MeV] Sn 0 2 4 6 8 10 12 15C Excitation energy [MeV] 15N(7Li,7Be)15C @ 55 MeV Fano interference: BSEC – s.p. continuum S.E.A. Orrigo et al., Proceedings Varenna122 p. 147 (2003) F.Cappuzzello, S.E.A. Orrigo et al., EuroPhys. Lett.65 p. 766 (2004)

  11. 15N(7Li,7Be)15C @ 55 MeV Single particle regime 35 30 25 20 15 10 5 0 Counts 0.77 qlab = 14° 55 keV/ch 0.77* DCP regime 8.50 7.30 6.77 8.50* ]6.4 7.30* g.s.* g.s. Sn 0 2 4 6 8 10 12 15C Excitation energy [MeV] 10 2 10 1 10 2 10 1 dQRPA(w) [MeV -1] s. p. a) level density natural paritytransitions Results of microscopic QRPA calculations • 15C: Fano Resonances • Strong competition of mean-field and correlation dynamics • mean-field approaches are no longer appropriate • Enhanced correlation effects (Dynamical Core Polarization DCP) • new excitation modes involving core-excited configurations (BSEC) 0 2 4 6 8 10 12 14 15C Excitation energy [MeV] Sn dQRPA(w) [MeV -1] b) level density unnatural parity transitions s. p. Sn 0 2 4 6 8 10 12 14 15C Excitation energy [MeV] • Strength well reproduced for single particle transitions (1/2+ g.s., 5/2+ state at 0.77 MeV) • Observed fragmentation for Ex > 2 MeV not reproduced S.E.A. Orrigo et al., Proceedings Varenna122 p. 147 (2003); F.Cappuzzello, S.E.A. Orrigo et al., EuroPhys. Lett.65 p. 766 (2004)

  12. 11B(7Li,7Be)11Be @ 57 MeV Counts Single particle DCP regime Sn 0 1 2 3 4 5 6 7 8 11Be Excitation energy [MeV] dQRPA(w) [MeV -1] s. p. a) level density natural paritytransitions 0 2 4 6 8 10 12 14 11Be Excitation energy [MeV] dQRPA(w) [MeV -1] b) level density unnatural parity transitions s. p. 0 2 4 6 8 10 12 14 11Be Excitation energy [MeV] 7Be detected with the IPN-Orsay Split-Pole magnetic spectrometer QRPA calculations • Strength well reproduced for single particle transitions (1/2+ g.s., 1/2- state at 0.32 MeV and 5/2+ state at 1.77 MeV) • Observed fragmentation for Ex > 2 MeV not reproduced F.Cappuzzello, H.Lenske et al., Phys. Lett B 516(2001)21

  13. The QPC model Strength fragmentation not reproduced by QRPA DCP effects • QPC Hamiltonian of the odd-masssystem: coupled by V13 1QP 3QP 1QP states 3QP states • Core excitations: 2QP exc. given by QRPA • Quasiparticle-core coupling (QPC) model(Bohr & Mottelson) • DCP correlations described by coupling 1QP to the core-excited configurations H.Lenske, J. Phys. G: Nucl. Part. Phys.24 (1998) 1429 H.Lenske, C.M.Keil, N.Tsoneva, Progr.in Part. and Nucl.Phys. 53 (2004) 153

  14. Theoretical model QPC eigenstates: 1QP 3QP s.p. mixing E < 0 bound states E> 0 continuum BSEC (EC) Bound core-excited states (E – EC < 0) To study resonances in the low-energy continuum and their line shapes S.E.A.Orrigo, H.Lenske et al., Phys. Lett. B633 (2006) 469

  15. Theoretical model By projecting the Schrödinger equation onto the 1-QP and 3-QP components N coupled equations 1QP Channel 1 3QP Channels i = 2, …, N Ch. 11QP continuum Ch. i = 2, …, N 3QP states Coupling of a single particle elastic channel to closed core-excited channels S.E.A.Orrigo, H.Lenske et al., Phys. Lett. B633 (2006) 469

  16. Numerical methods 1QP Channel 1 (open) 3QP Channels i = 2, …, N (closed) r < RA r >> RA • Potentials Ui from HFB calculations • Transition form factors from QRPA calculations & data The coupled channels problem is solved in coordinate space N coupled equations for the radial wave functions S.E.A.Orrigo, H.Lenske et al., Phys. Lett. B633 (2006) 469

  17. Numerical methods 1) Internal w.f. by solving the NxN eigenvalue problem r < RA i = 1, …, N 2) Asymptotic w.f. r >> RA i = 1, …, N • Matching 2N equations with complex coefficients bm, C1i i = 1, …, N S.E.A.Orrigo, H.Lenske et al., Phys. Lett. B633 (2006) 469

  18. Results for 15C s-, p-, d-waves s11 [mb] 12 s - wave V13 0 p - wave 10 d - wave 8 Fano interference 6 4 2 0 0 5 10 15 20 25 30 15C excitation energy [MeV] s11 [mb] 12 s - wave V13= 0 p - wave 10 d - wave 8 6 4 2 0 0 5 10 15 20 25 30 15C excitation energy [MeV] • Elastic scattering cross section • Analytic calculation for 2 ch. • A single excited state of the 14C core: EC = 8.317 MeV • Ui from HFB • V13 is the only free parameter S.E.A.Orrigo, H.Lenske et al., Phys. Lett. B633 (2006) 469

  19. Results for 15C • Full 5-channels calculation • 4 14C states: EC(Jp) = 6.094(1–), • 6.728(3–), 7.012(2+), 8.317(2+) MeV • Ui from HFB • V13 weighted by b(i) of 14C(a,a’) JC   15C theo. (s11 d-wave) • V13 is the only free parameter 15C exp. from (7Li,7Be) • Qualitative comparison: • Eth. = 6.67, 7.36, 7.70, 8.92 MeV • Gth.= 66, 80, 141, 85 keV • Eexp. = (6.77, 7.30, 8.50)  0.06 MeV • Gexp. ≤ 160, 70, 140 keV • V13affectsG of the resonances (here V13 = 5 MeV) S.E.A.Orrigo, H.Lenske et al., Phys. Lett. B633 (2006) 469

  20. Results for 17C and 19C 70 d-wave 60 50 40 30 s11 [mb] s11 [mb] 20 10 17CSn = 0.73 MeV 19CSn = 0.16 MeV 0 0 2 4 6 8 10 12 100 d-wave 90 80 70 60 50 19C excitation energy [MeV] 17C excitation energy [MeV] 40 Increased effect of the correlations 30 BSEC structures move towards lower energies with increasing the neutron excess 20 10 0 0 2 4 6 8 10 12 • Systematic study of the evolution of the phenomenon when going towards more n-rich nuclei V13 is the only free parameter (here 5 MeV) State parameters by QRPA 16C states: EC(Jp) = 1.766(2+), 3.986(2+), 4.142(4+) MeV 18C states: EC(Jp) = 1.620(2+), 2.967(4+), 3.313(2+), 5.502(1–) MeV S.E.A. Orrigo, H.Lenske et al., Proceedings INPC07, Tokyo

  21. The (7Li,7Be) CEX reaction N a + 3 n • Structural properties: • Single particle isovector excitations • BSEC and Fano resonances • in the continuum • Reaction dynamics: • One-step / two-step contributions • Spin transfer probabilities • N = 1 7He • N = 2 11Be • N = 3 15C • N = 4 19O • N = 5 23Ne • N = 6 27Mg • … IPN-Orsay MAGNEX References: S.E.A. Orrigo et al.,Core excited Fano-resonances in exotic nuclei, Phis.Lett. B 633(2006)469 F.Cappuzzello, S.E.A. Orrigo et al., Excited states of 15C, EuroPhys.Lett.65(2004)766 F.Cappuzzello et al., Analysis of the 11B(7Li,7Be)11Be reaction at 57 MeV in a Microscopic Approach,Nucl.Phys. A 739(2004)30 S.E.A. Orrigo et al., Spectroscopy of 15C by (7Li,7Be) Charge Exchange Reaction, Proc. “10th Int. Conf. on Nuclear Reaction Mechanisms” , Varenna, Italy, 122(2003)147 C.Nociforo et al., Investigation of light neutron-rich nuclei via the (7Li,7Be) reaction, Acta Physica Polonica, B 34(2003)2387 F.Cappuzzello et al., Excited states of 11Be, Phys.Lett B 516(2001)21

  22. MAGNEX Upper bent limits E < 30 AMeV 2 < A < 40 E < 25 AMeV 40 < A < 93 A.Cunsolo et al., NIMA 481 (2002) 48 A.Cunsolo et al., NIMA 484 (2002) 56

  23. 19F(7Li,7Be)19O @ 52.4 MeV g.s. E/DE ~ 1000 96 keV 19O qlab = 7° - 19.5° W = 50 msr Energy byte = ± 27% PRELIMINARY Counts 19.8 keV/ch Xfoc [m] Sn = 3.9 MeV

  24. Contents • Physical scenario: light exotic nuclei • Correlations effects and continuum spectroscopy • DCP correlations: Fano resonances • Experimental results on 11Be and 15C via CEX reactions • Pairing correlations in the continuum • Transfer reactions to unbound states: 9Li(d,p)10Li • Summary and conclusions • Single particle dynamics: the relevant energy scale is Sn-l-D • Stable nuclei: Sn~10MeV • → static MF in the p-h channel + paring for the p-p correlations • Weakly-bound n-rich nuclei: Sn~few keV-MeV • → pairing correlations in the p-h channel are also important

  25. Theory of Pairing in the Continuum • Similarity between the Pairing and DCP approaches • Particle-stable system: lq<0 • ea-<0 , hole w.f. va decaying exponentially for r»RA • In the continuum ea+>0, particle w.f. ua like a scattering wave: • Extended MF approach for pairing in weakly-bound or unbound nuclei • 2x2 coupled channel problem described by the Gorkov equations • H.Lenske, F.Hofmann, C.M.Keil, J. Progr. Part. Nucl. Phys.46(2001)187 • Particle channel (open) • Hole channel (closed)

  26. Theory of Pairing in the Continuum Relationship scattering observables – pairing strength • Continuum level density: spectral distribution of particle strength per energy E • = Density of states • Partial wave elastic scattering cross section: Resonances in resonances in sℓj • Observables involving the states ua will show a characteristic energy dependence • (e.g., transfer cross sections through Sa(E)) • The same type of effects is produced by any types of correlations (e.g., DCP → Fano) S.E.A. Orrigo and H. Lenske, submitted to PLB (2008)

  27. Neutron s.p. spectral functions in 9Li E<0 hole sector E>0 particle sector • Effects of the dynamical correlations (particle-hole coupling) due to the pairing field • The widths of the hole distributions (E<0) are due to the bound-continuum coupling • The deeper-lying s-wave levels are coupled more efficiently to the particle continuum • The 5/2+d-wave strength is lowered into the bound state sector (intruder component) • A small amount of 1/2+ and 3/2+ strengths is above the p½ peak • Dramatic change in dynamics at the n-dripline: the level ordering is not determined by simple MF S.E.A. Orrigo and H. Lenske, submitted to PLB (2008)

  28. Partial wave cross sections for elastic scattering 9Li+n The structure results are used as input for transfer reaction calculations • Comparison: full HFB Gorkov-pairing – bare MF calculations • Pairing gives an attractive self-energy in the p-wave channels • → 1/2– and 3/2– resonances at very low energy (E<<3MeV ~ threshold for DCP correlations) • Slight attraction in the 1/2+ channel and repulsion for the d-waves S.E.A. Orrigo and H. Lenske, submitted to PLB (2008)

  29. Continuum spectroscopy of 10Li by transfer reactions • Transfer reactions well established tool for structural studies of bound and exotic nuclei • Weakly-bound final state: prevalence of small momentum components the cross section maximum is at much lower incident energies H. Lenske and G. Schrieder, Eur. Phys. J2 (1998) 41 • Single-nucleon transfer reactions as a tool for continuum spectroscopy in exotic nuclei • Study of the low-energy s.p. resonances in unbound systems also • Method based on a DWBA approach.Main innovations: to treat the case of unbound final states and to calculate the double differential cross section for one-neutron transfer • The model is applied to the 9Li(d,p)10Li reaction to explore the structure of 10Li 10Li is neutron-unbound by 25 ± 15 keV

  30. Why 10Li? • Crucial for the comprehension of the structure of 11Li as a three body system • (11Li is a Borromean 2-n-halo nucleus) • Information on the n-9Li interaction, important for the theoretical models of 11Li • Interest in the structure of 10Li itself: low-lying states are not yet well known • Ground state: p-wave or s1/2 virtual state at the n+9Li threshold? • 4 states are expected at low energy with Jp = 1−, 2− and 1+, 2+ • (neutron in 2s1/2 or 1p1/2unpaired 1p3/2 proton of the 9Li core) • Two resonances seen at Ex~ 250 and 500 keV; several resonances at higher Ex D.R. Tilley et al., Nucl. Phys. A 745 (2004) 155 and refs. therein • Interest in the 9Li(d,p)10Li reaction in inverse kinematics: • experiments at MSU @ 20 AMeV (P. Santi at al., Phys. Rev. C 67 (2003) 024606) resonance at ~ 350 keV with G~ 300 keV • experiments at REX-ISOLDE @ 2.36 AMeV (H.B. Jeppesen et al., Phys. Lett. B642 (2006) 449) resonance at ~ 380 keV with G~ 200 keV

  31. Theory for transfer reactions -36.14 • Transfer reaction A(a,b)B (a = b+x, B = A+x) in a DWBA approach [Satchler] • Optical model Hamiltonians and DW Schroedinger equations: • Ha = HA + Ha + Ka + Ua + Va (a = a+A) ; Hb = HB + Hb + Kb + Ub + Vb (b = b+B) • (Kg + Ug – Eg) cg(±) (rg, kg) = 0 (g = a, b) • The optical model wave functionscg(±) (rg, kg) describe the elastic scattering determined • by the optical potentials Ug at the channel energies Eg = E – eA – ea Hinterberger Menet d-potentials p-potentials NPA111(1968) PRC4(1971) Residual interaction Vb (post) chosen according to effective self-energy (full HFB Gorkov-pairing), it reproduces B.E., rM, rC of 9Li

  32. Theory for transfer reactions • for a fixed energy • In the post representation for a stripping reaction in which x is transferred from a to B: • Fba = JB MB sb mb | V | JA MA sa ma = • =Sjl (Sjl)½ Rjl(rxA)(l s m m – m | j m)(sb s mb ma – mb | sa ma)(JA j MA MB – MA | JB MB)D(rxb) Ylm*( ) • spectroscopic amplitude radial wave function for the transferred particle x • projectile internal function times x-b interaction potential • Zero-Range Approximation: • D(rxb) = D0d(rx – rb)Tba = D0 (Sb)½cb(–) | R(rx)Y*( ) d(rx – rb) | ca(+) • which contains dynamics and structure information ˆ r xA • First order DWBA transition amplitude: • Tba = cb(–) | Fba | ca(+) • Fba = bB|V|aAform factor

  33. Theory for transfer reactions to unbound states Double differential cross section for one-nucleon transfer to unbound final states Momentum distribution (Dynamics: Fourier transform of the wave function) Spectral function (Structure: probability per energy for finding the particle in state ℓj at energy E) • Transfer into the continuum: • The B = A+x final states are unbound against the reemission of the nucleon x (ex< 0) • the overlap form factor oscillates at large distances • the DWBA radial integrals converge very slowly • Vincent and Fortune: • powerful method of contour integration in the complex radius plane to overcome the convergence problem C.M. Vincent and H.T. Fortune, PRC2(1970); PRC7(1973); PRC8(1973) S.E.A. Orrigo and H.Lenske, submitted to PLB (2008)

  34. Spectroscopy of 10Li = 9Li+n at the continuum threshold ds[mb/MeV] dE 16 Angle-integrated cross sectiond(9Li,10Li)p @ 2.36 AMeV Total d(9Li,10Li)p qcm = [98°,134°] data 14 1/2+ 3/2- 1/2- 12 5/2+ 3/2+ 10 S.E.A. Orrigo and H. Lenske, submitted to PLB (2008) 8 H.B. Jeppesen et al., PLB 642(2006)449 ER~ 380 keV, G~ 200 keV 6 4 2 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 E [MeV] • p1/2 resonance at ER = 400 keV Mainly a potential resonance • p3/2 resonance at ER = 850 keV Coupled-channels pairing resonance • New feature essential to describe data • obtained by adding a polarization repulsive surface potential (acting in DE~250keV around ER) to reproduce the full HFB Gorkov-pairing results • The theoretical results include the experimental energy resolution GFWHM~250keV • Good agreement with data (shape and resonances position)

  35. Angular distributions Angular distributionsd(9Li,10Li)p @ 2.36 AMeV 100 Total ds [mb/sr] dW data d(9Li,10Li)p 1/2+ 3/2- 1/2- 5/2+ 10 3/2+ S.E.A. Orrigo and H. Lenske, submitted to PLB (2008) H.B. Jeppesen et al., PLB 642(2006)449 ER~ 380 keV, G~ 200 keV 1 0.1 0 20 40 60 80 100 120 140 160 180 qcm [deg.] • Good agreement with data (no scaling) • The p1/2-wave is dominant • As expected, transfer is favoured at low incident energies: • calculations @ 20 AMeV (MSU exp.) →stransfer at ER(p1/2) is lowered by a factor of 26 • The measurement of angular distributions is important to identify the 10Li states (ℓp values)

  36. Transfer 9Li(d,p)10Li @ 2.36 AMeV, before folding, qcm =[98°,134°] dsR[mb/MeV] dE 12 • Same structure for selastic and stransfer: a physical resonance appears in both dℓj(E) [°]→ Sℓj(E) Access to the spectroscopic information by transfer • However, in stransfer there can be not physical resonances also, due only to the reaction dynamics part p1/2 p3/2 10 8 6 4 140 2 120 0 0 0.2 0.4 0.6 0.8 1 100 E [MeV] dsE[mb/MeV] dE 80 8000 p1/2 E [MeV] 60 p3/2 7000 40 6000 5000 20 4000 0 0 0.2 0.4 0.6 0.8 1 3000 2000 1000 0 0 0.2 0.4 0.6 0.8 1 E [MeV] • Elastic scattering n+9Li (p-wave) S.E.A. Orrigo and H. Lenske, submitted to PLB (2008)

  37. Spectral distribution ↔ properties of n-9Li interaction 18000 Elastic scattering n+9Li (p1/2-wave) 16000 dsE[mb/MeV] dE c, R c + 10% c – 10% R + 10% R – 10% 14000 12000 10000 8000 E [MeV] 6000 Information on the residual n-9Li interaction 4000 2000 0 0 0.2 0.4 0.6 0.8 1 • Variations by ±10% of the potential • diffuseness c and radius R • IVol = 486.62 (AMeV)·fm3 = constant • p1/2-wave:ER, G strongly sensitive to c • (asymptotic shape of potential, halo tail) • Scattering length as = 1.69 fm • (c+10%)=1.68 fm, (c-10%)=1.72 fm • (R+10%)=2.21 fm, (R-10%)=1.06 fm • s1/2-wave: larger sensitivity to R • (no centrifugal barrier) S.E.A. Orrigo and H. Lenske, submitted to PLB (2008)

  38. Summary • Fano resonancescan be expected to be of particular importance for the continuum dynamics of exotic nuclei • The coupled channels model extends the QPC into the continuum: the interference between open 1-QP and closed 3-QP ch. gives sharp and asymmetric resonances (G→V13) • The calculations performed for 15C, 17C, 19C show increased effects of correlations • Exp. evidence of DCP correlations in the 15C spectra, qualitatively reproduced by theoretical calculations, and in the 11Be and 19O spectra • Transfer reactions are a powerful tool to do continuum spectroscopy in exotic nuclei • Innovations of the DWBA approach: to treat unbound final states and to calculate d2s/dWdE • Calculations performed for the d(9Li,10Li)p reaction at ELi = 2.36 and 20 AMeV • 10Li continuum: p1/2-resonance at ~400 keV and p3/2-pairing resonance at~850 keV in very good agreement with experimental data • Same behaviour of selastic and stransfer: same structure Sa(E) • Correlation: spectral distributions ↔ n-9Li interaction (sensitivity to the halo tail)

  39. Summary • Pairing in unbound nuclear states explored in terms of an extended MF approach • Paring effects may introduce pronounced structures and shifts in the low-energy continuum of all the channels • Configuration mixing acts at the MF level, but mechanisms similar to the mixing due to dynamical correlations Analogy: Configuration Mixing due to 15C continuum = n+14C, BSEC = n+14C* core polarization (DCP) 10Li continuum = n+9Li unbound, (particle-hole) pairing correlations (MF-level) ☺ Thank you for your attention ☺

More Related