6He??6Li????N-N??????

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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
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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?
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New 2n correlation experiment (Nakamura et al.)
Taken from K. Hagino
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2. Eikonal and adiabatic approximations
--- Case of one-neutron halo nucleus ---
Eikonal approximation
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DEA (Dynamical Eikonal Approximation)
Adiabatic approx.
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Test of DEA
11Be208Pb 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)
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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
a n n three-body model for 6He
CDCC
T. Matsumoto et al. PRC70 (2004)
RCNP.08
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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)
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Test of CCE
Breakup of 11Be (one-neutron halo nucleus) on Pb
PTP 112 (2004)
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CCE vs DEA
b-dep. of elastic breakup probability 11Be on
208Pb at 69 MeV/nucleon
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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 a n n
three-body model Bound and continuum states of
6He are described with HHE
PRC submitted
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6He breakup on 208Pb at 70 MeV/A
--- Contribution of partial cross sections ---
Cross sections are directly measurable. Determinin
g 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.
J0,2 contributions 10 at low energies, 35 at
E5MeV
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--- Double differential cross sections from 1-
component ---
information on correlations
1
Core
2
The peak corresponds to the broad 1- resonance.
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6He breakup on 208Pb at 240 MeV/A
No convolution
Dashed, dotted denote 1- partial cross sections
T. Aumann et al. PRC59 (1999)
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E1 strength distribution of 6He
Myo et al. PRC63 (2001)
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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 6He208Pb at 70 and 240
MeV/nucleon. The results disagree with the 240
MeV data. B(E1) strength? Further new data
are desirable.