Unified studies of light neutron-excess systems
from bounds to continuum
－Structural changes and Reaction dynamics in Be isotopes －
Makoto Ito
Department of Pure and Applied Physics, Kansai University
I. Introduction
II. Framework
III. Various structures in 12Be and Be isotopes
IV. Enhancements induced by level crossing
V. Summary and feature plan
IKEDA Diagram
Cluster structures in 4N nuclei
Ikeda’s Threshold rules
Molecular structures will
appear close to the
respective cluster threshold.
H.O. quanta N
<N> ± DN
Be isotopes
～ 34.6 ± 5.9
Molecular Orbital : Itagaki et al,….
α-Particle ⇒ building block
p―
s+
PRC61,62 (2000)
3H+p
～ 20 MeV
Clustering phenomena is
generated by a huge mixing
of shell model configuration.
Studies on Exotic Nuclear Systems in (Ex,N, Z,J) Space
Slow RI beam
1. Structures of 8～16Be
2. Breakup of 10,12Be
Low-lying
Molecular Orbital :
p ―、s＋‥
Ex. energy
Unbound Nuclear Systems
Is Threshold
Rule valid ??
Decays in
Continuum
Structural
Change
N
( N,Z ) : Two Dimensions
Extension of microscopic cluster model (Test calculation for 10Be)
10Be=a+a+N+N
Mol. Orb.
Combine
a
6He
5He
5He
Unified model between M.O. and He clusters :PLB588 (04)
Y=
C1
+
C2
+
C3
0Pi (i=x,y,z) Coupled channels with Atomic orbitals
Absorbing B.C.
...
S
Scattering B.C.
S, Ci : Variational PRM.
Tr. densites
<CL | r| MO>
Decay widh
PTP113 (05)
ｰi W(R)
a+6He Cross sections
PLB636 (06)
→ a+6He
Breakup
10Be
Femto Molecules ：12Be=a+a+4N
Covalent
(0pR)(0pL) (s+)2
6He
6He
5He
NN: Volkov No.2+G3RS
7He
Ionic
a+8He ⇒ 6He+6He
06+
05+
Atomic
04+
Neutrons’ ex.
03+
6He
+ 6He
a + 8He
8He
Ionic
(p-)2(p-)2
Clusters’
Relative ex.
02+
Various structures are
generated by excitation
of a-a and neutron degree
of freedom.
01+
(p-)2 (s+)2
Be isotopes from bounds to continuums : Jp = 0+
8Be
10Be
Deformed states (Clusters)
Compact states (Shell model)
12Be
14Be
Excitation of
a-a rel. motion
16Be
xHe
yHe
Level Crossings scheme in Be isotopes
We can discuss reaction dynamics in
connection to level crossing scheme.
C+D
Energy
Internal
States
A+B
Clusters
( Intruder )
Level Crossing
Asymptotic
States
Compact
( Normal )
Small
Core-Core distance
Large
Level Crossings in 12,14Be=a+a+XN (X=2,6)
10Be
14Be
(0p)2(sd)4
a + 6Heg.s.
Level Crossing
8He
g.s.
+ 6Heg.s.
(sd)2
Level Crossing
(0p)2
(0p)4(sd)2
GTCM + Absorbing Boundary Condition : PLB (2006)
Adiabatic surfaces (Jp = 0+)
Energy spectra ( Jp = 0+ )
a+6He(21+)
Cluster
ｰi W(R)
Nuclea breakup : 10Be +12C ⇒ 10Be(0+ conti.) + 12C (CDCC cal.)
Smat.( Conti.←G.S. )
S-matrices to continuums
Smat.( Poles ← G.S.)
S-matrices to Poles
03 +
03+
04+
04+
Reaction path in 10Be → xHe + yHe Breakup reaction (Positive Parity)
10Be(0+)
→ [ a + 6He(21+) ] 0+
03+
Reaction Path in Breakup
×
01+
01+ → 03+ is the dominant transition.
Non-adiabatic tr. is main process.
Level Crossing in
12Be
(2) : breaking of N=8 magic number and level crossing
Correlated AESs
Correlation
a + 8Heg.s.
AESs with full coupling
a + 8Heg.s.
Coupling
with all
configurations
Conjunction
G.S.⇔ a+8He
(p-)2 (s+)2 [(0p)4(sd)2]
(p-)2 (p-)2 [(0p)6]
G.S.
Lowest minimum smoothly connected to a+8He g.s. ⇒ Formation of adiabatic conjunction
Monopole transition of 12Be
M ( E 0, IS ) = 0

f
A
2

r
0
i 1
Adiabatic transition is main process
in monopole transition.
M ( E 0, IS )
i =1
8He
03+
01+ → 03+ is enhanced.
(p-)2 (s+)2
01+
2
Contents of present report
1. Unified studies form bounds to continuums in Be isotopes
2. Reactions with large amplitudes in connection to adiabatic energy surfaces
Results
1. There appears a wide variety of structures in excited states (Cluster + excess N)
2. Enhancements occur depending on the structures of AESs.
10Be
: Non-adiabatic path is dominant in monopole breakup .
12Be
: Adiabatic path is dominant in monopole breakup (breaking of N=8 magic).
Feature studies
Recently, we have just succeeded in extending the model to general two centers.
Extension to SD shell ⇒ O=a+12C+XN、Ne=a+16O+XN
Generalities and Specialities : hybrid structures of clusters + excess neutrons in O and Ne