Breakup of halo nuclei with Coulomb-corrected eikonal method

1. Breakup of halo nuclei with Coulomb-corrected eikonal method Y. Suzuki (Niigata) • Motivation for breakup reactions • Eikonal and adiabatic approximations • Coulomb-corrected eikonal model • 4. Application to 2n halo nuclei Collaborators: B. Abu-Ibrahim (Cairo) P. Capel, D. Baye, P. Descouvemont (ULB) PTP112 (2004), PTP114(2005), PRC78(2008), PRC submitted

2. 1. Motivation ・Breakup reactions are important to study halo nuclei which are characterized by weakly bound, short-lived, few-cluster structure ・E1 strength, NN correlation are deduced from breakup cross sections FSI, breakup into continuum ・Sound reaction theory is needed to extract structure information Perturbation expansion, Adiabatic approximation, Eikonal approximation, CDCC, … Information on B(E1) distribution First-order perturbation theory for Coulomb breakup Contribution of other multipoles to breakup cross sections?

3. New 2n correlation experiment (Nakamura et al.) Taken from K. Hagino

4. Projectile f C Target 2. Eikonal and adiabatic approximations --- Case of one-neutron halo nucleus --- Eikonal approximation

5. DEA (Dynamical Eikonal Approximation) Adiabaticapprox.

6. Test of DEA 11Be+208Pb at 69 MeV/nucleon Angle-integrated cross sections as a function of the relative energy of n-10Be fragments G. Goldstein et al. PRC73 (2006) N. Fukuda et al. PRC70 (2004)

7. 40 MeV/nucleon Folding Eikonal approx.: N-12C optical potential Full Glauber model: 3α microscopic cluster model w.f. for 12C NN profile function Test of eikonal and adiabatic approximations --- Breakup effect in elastic scattering of 6He on 12C --- V. Lapoux et al. PRC66 (2002) B. Abu-Ibrahim & Y.S. NPA728 (2003) VMC w.f. for 6He α+ n + n three-body model for 6He CDCC T. Matsumoto et al. PRC70 (2004) RCNP.08

8. 3. Coulomb-corrected eikonal Rutherford scattering Long-ranged breakup effect(adiabatic approx. breaks down) Logarithmic divergence Coulomb-corrected eikonal phase (CCE) J. Margueron et al. NPA703 (2002)

9. Test of CCE Breakup of 11Be (one-neutron halo nucleus) on Pb ＰＴＰ 112 (2004)

10. CCE vs DEA b-dep. of elastic breakup probability 11Be on 208Pbat 69 MeV/nucleon

11. 4. Application to breakup of two-neutron halo nucleus Challenging four-body problemincluding continuum final states ・Expensive computation time ・Final-state interaction ・Extraction of E1 strength function or effects of other multipoles Case study: 6He breakup on 208Pb at 70, 240 MeV/A ・Reaction dynamics is fully taken into account in CCE model ・ 6Heis described with α+ n + n three-body model ・Bound and continuum states of 6He are described with HHE PRC submitted

12. 6He breakup on 208Pb at 70 MeV/A --- Contribution of partial cross sections --- Cross sections are directly measurable. Determining E1 strengths relies on model assumptions (e.g. 1- dominance, elimination of nuclear effects). Dotted lines denote final plane waves Comparison with solid lines denotes the importance of FSI. J=0,2 contributions: 10% at low energies, 35% at E=5MeV

13. --- Double differential cross sections from 1- component --- information on correlations 1 Core 2 The peak corresponds to the broad 1- resonance.

14. 6He breakup on 208Pb at 240 MeV/A No convolution Dashed, dotted denote 1- partial cross sections T. Aumann et al. PRC59 (1999)

15. E1 strength distribution of 6He Myo et al. PRC63 (2001)

16. Summary ・A correction is introduced to avoid the divergence due to the Coulomb interactionin the eikonal model. ・The CCE is accurate enough to take into account the reaction dynamics, making it possible to reconstruct the properties of two- and three-body projectile wave functions. ・Bound and continuum states of three-body system are described in HH basis with full account of final state interactions. ・Various cross sections, in particular including multi-differential cross sections can be calculated. ・The contribution of various multipole transitions is quantified. ・The CCE is applied to 6He+208Pb at 70 and 240 MeV/nucleon. The results disagree with the 240 MeV data. B(E1) strength? Further new data are desirable.