RCNP.08

Breakup of halo nuclei with Coulomb-corrected eikonal method

Y. Suzuki (Niigata)

1. Motivation for breakup reactions 2. Eikonal and adiabatic approximations 3. Coulomb-corrected eikonal model4. 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

・ 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, …

1. Motivation

Information on B(E1) distribution First-order perturbation theory for Coulomb breakup

Contribution of other multipoles to breakup cross sections?

New 2n correlation experiment (Nakamura et al.)

Taken from K. Hagino

Target

C

f

Projectile

Eikonal approximation

2. Eikonal and adiabatic approximations

--- Case of one-neutron halo nucleus ---

DEA (Dynamical Eikonal Approximation)

Adiabatic approx.

11Be+208Pb at 69 MeV/nucleon Angle-integrated cross sections as a function of the relative energy of n-10Be fragments

Test of DEA

G. Goldstein et al. PRC73 (2006)N. Fukuda et al. PRC70 (2004)

RCNP.08

Test of eikonal and adiabatic approximations

α+ n + n three-body model for 6He CDCC

T. Matsumoto et al. PRC70 (2004)

Glauber model: 3α microscopic cluster model w.f. for 12CNN profile function

Eikonal approx.: N-12C optical potential

Folding

Full

40 MeV/nucleon VMC w.f. for 6He

--- Breakup effect in elastic scattering of 6He on 12C ---

B. Abu-Ibrahim & Y.S. NPA728 (2003)

V. Lapoux et al. PRC66 (2002)

Logarithmic divergence

Coulomb-corrected eikonal phase (CCE)

3. Coulomb-corrected eikonal

Long-ranged breakup effect (adiabatic approx. breaks down)

J. Margueron et al. NPA703 (2002)

Rutherford scattering

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

Test of CCE

b-dep. of elastic breakup probability 11Be on 208Pb at 69 MeV/nucleon

CCE vs DEA

4. Application to breakup of two-neutron halo nucleus

Challenging four-body problem including 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・ 6He is described with α+ n + n three-body model・ Bound and continuum states of 6He are described with HHE

RCNP.08

PRC submitted

6He breakup on 208Pb at 70 MeV/A

Dotted lines denote final plane wavesComparison with solid lines denotes the importance of FSI.

--- 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).

J=0,2 contributions: 10% at low energies, 35% at E=5MeV

--- Double differential cross sections from 1- component ---

Core

1

2

information on correlations

The peak corresponds to the broad 1- resonance.

6He breakup on 208Pb at 240 MeV/A

Dashed, dotted denote 1- partial cross sections

T. Aumann et al. PRC59 (1999)

No convolution

E1 strength distribution of 6He

Myo et al. PRC63 (2001)

RCNP.08

Summary

・ A correction is introduced to avoid the divergence due to the Coulomb interaction in 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.