Transcript Document

Cluster Phenomena in Stable and
Unstable Nuclei
Y. Kanada-En’yo (Kyoto Univ.)
Collaborators:
Y. Hidaka(RIKEN), T. Ichikawa(YITP),
M. Kimura(Hokkaido), F. Kobayashi(Kyoto),
T. Suhara (Matsue) ,Y. Taniguchi(NIMS), Y. Yoshida (Kyoto)
1.Introduction
Cluster structures
in stable and unstable nuclei
Typical cluster structures known in stable nuclei
7Li
8Be
a+t
a+a
Heavier nuclei
Si-Si, Si-C, O-C, O-O
12C
20Ne
3a
16O
16O*
+a
12C
+a
Unstable nuclei
a-cluster
3a linear chain
excitation
a
a-cluster
36Ar-a, 24Mg-a, 28Si-a
40Ca*, 28Si*, 32S*
Molecular
orbital
14C*
Be, C, O, Ne, F
Cluster & Mean field
Cluster:
Many-body correlation
Mean field, shell structure
Independent single-particle
Shell structure・MF
Independent particle
in MF
v.s.
Cluster formation
many-body correlation
no correlation
g.s. correlation
Cluster
Cluster excitation
Developed cluster
excited states
Cluster structures
Nuclear
structure
0 MeV
Shell & cluster corr.
12C
cluster excitation
+
Nucleon liquid
high density
100 MeV Energy
10 MeV
r0
Cluster gas, crystal
r0/3~ r0/5
Nucleon gas
low density
Cluster
enhancement
Cluster phenomena in low density
Heavy Ion
collision
Multi
fragmentation
AMD cal.: 129Xe+Sn E/A 50 MeV
by A. Ono PRC66 (2002)
Liquid-gas phase
Supernova,
Neutron star crust
Nuclear pasta
QMD cal.
by Watanabe PRL109 (2009)
Cluster structures
in n-rich nuclei
gs cluster
correlation
stable
nuclei
cluster gas
cluster
weakening/
melting
n-rich
nuclei
Clustering
in deformed
Neutron density
 n-skin suppression
 large deformation
 breaking of magic
number N=8, N=20
n-rich Be, F, Ne
a-cluster
excitation
Molecular
orbital
n-rich C
linear chain
in C*
Roles of excess neutrons
in cluster structures of n-rich nuclei
Soic et al., Freer et al., Saito et al.,
Scholz et al., Rogachev et al., Goldberg et al.,
Curtis et al., Milin et al., Bohlen et al.,
Ashwood et al., Yildiz et al.,
Seya, Von Oerzten, Descouvemont et al., Descouvemont, Kimura,
Itagaki et al., Dote et al., K-E et al.
Arai et al., M. Ito et al.
18
10Be
6He+He
a
a
a
a
aa
Atomic:
Cluster resonance
Molecular Orbital:
bonded clusters
Normal states
Be isotopes
O+a
a
16O
16O
a
Weak
coupling
Strong
coupling
shell
model-like
Ne, F, O isotopes
MO bond and Cluster res. in 22Ne
Exp Scholz et al., Rogachev et al., Goldberg et al.,Ashwood et al., Yildiz et al.,
Theor: Descouvemont, Kimura,
22Ne
AMD study by Kimura, PRC75 (2007)
18O+a
a
16O
16O
EXP
AMD
a
Cluster res.
MO-bond
MO structures in F isotopes
AMD study by Kimura et al., PRC83 (2011)
19-29F
a
MO bond with
15N+a core
3hw
2hw
1hw
3hw
2hw
0hw
19F 21F 23F 25F 27F 29F
play an important
role in lowering
intruder states
in N~20 region
also in Ne isotopes
a-cluster states in n-rich nuclei
Cluster resonances
a
New states discovered and suggested at
Ex = several ~ 20 MeV
in a-decay, a-transfer, a-scattering
6,8He+a
10Be+a
in Be
in 14C
14C+a
in 18O
18O+a
in 22Ne
Exp: Soic et al., Freer et al., Saito et al., Curtis et al., Milin et al., Bohlen et al.,
Theor: Seya, von Oerzten, Descouvemont et al.,Itagaki et al., K-E et al.
Arai et al., M. Ito et al.
Exp Soic 04, von Oertzen ‘04, Price 07, Haigh 08,
Theor: Suhara ‘10
Exp Scholz et al., Rogachev et al., Goldberg et al.,Ashwood et al., Yildiz et al.,
Theor: Descouvemont, Kimura,
Exp Scholz ‘72, Rogachev ‘01, Goldberg ‘04, Ashwood ‘06, Yildiz et al.,
Theor: Descouvemont ’88, Kimura ‘07
-> information of nucleus-nucleus potential and valence neutron
effects there.
Rich cluster phenomena in
nuclear systems
as functions of proton&neutron numbers and excitation energy
 Cluster formation/breaking in low-lying states
 Cluster excitation and resonances
 Molecular Bond in neutron-rich nuclei
 Many clusters : cluster gas, chain
 New types of cluster
6,8He+He
in Be, 10Be+a in 14C,14C+a in 18O, 18O+a in 22Ne
A theoretical method:
AMD (antisymmetrized molecular dynamics)
2. A theoretical model:
AMD
An approach for nuclear structure to study
•
cluster and mean-field aspects
•
Stable and unstable nuclei
•
Ground and excited states
AMD method for structure study
AMD wave fn.
Gaussian
wave packet
Slater det.
Gaussian
spatial
Intrinsic spins
det
isospin
Similar to FMD wave fn.
Energy Variation
Effective nuclear force
phenomenological)
A variety of
cluster st.
Shell-model
like st.
3. Some topics of
cluster phenomena
3-1. MO bond in n-rich Be
& vanishing of magic number
3-2. Cluster resonances
3-3. Linear chain in n-rich C
3-1. MO bond in n-rich Be
& vanishing of magic number
3-2. Cluster resonances
3-3. Linear chain in n-rich C
Cluster structures
in neutron-rich Be
cluster
res.
10Be:
6He+4He
energy levels
AMD calc. Y. K-E, et al. PRC (98)
Exp: Milin et al. ’05, Freer et al. ’06
+
03
Ito et al.
Kobayashi et al.
Kuchera et al.
4+
MeV
4+
10
2+
+
MO bond
02
0+
exp
5
AMD
Normal
+
01
2+
0
0
5
10Be
10
15
J(J+1)
20
Molecular orbital(MO) structure in Be
Seya PTP65(81), von Oertzen ZPA354(96)
N. Itagaki PRC61(00), Y. K-E.. Ito PLB588(04)
2a-core formation
MO formation
+
α
-α +
MO state
s-orbital
MO formation
±
α
+
-
α
p-orbital
Normal state
Gain kinetic energy
in developed 2α system
Level inversion
in 11,12,13Be
vanishing of magic number in 11Be, 12Be, 13Be
Vanishing of N=8 magic number
in neutron-rich Be
Y.K-E.PRC (03),(12) , Ito PRL(08) Dufour NPA(10)
Fortune PRC(06), Blanchon PRC(10)
Energy
10Be
+
02
12Be, 11,13Be
 deformation in 12Be(gs)
Inelastic scat. life time:
Iwasaki PLB481(00),
Imai PLB673(09)
Normal 0hw
MO bond
p
s
s
p
+
01
+
02
 intruder config. in 12Be(gs)
1n-knockout reac.:
Navin PRL85(00),
Pain PRL96(06)
Intruder 2hw
+
01
Normal state

12Be(0 +)
2
with p-shell config.
Shimoura PLB654 (07)
B(GT) with charge ex.:
Meharchand PRL108 (12)
n-rich
12Be
g.s. 0+
13Be
g.s. 1/2-
 abnormal parity of 13Be(gs)
Kondo et al. PLB690 (10)
Breaking of magic number in 13Be
13Be:
unbound
13Be spectra measured by 1n knock-out reactions
at GSI(Simon et al. 2007) and RIKEN(Kondo et al.,2010)
Er
(MeV)
13Be
AMD calc. Y. K-E. PRC(12)
EXP.
(1/2-)
3.04
(5/2+)
2
1
0
12Be+n
(5/2+)
2.39
2.0
AMD Kondo10 Simon07
12Be+n
1/2- ?
1/2+ virtual st.
Simon07
(1/2-)
0.51
Kondo10
intruder
d5/2
p1/2
s1/2
p3/2
s1/2
1/2- is lowest
in 13Be
3-1. MO bond in n-rich Be
& vanishing of magic number
3-2. Cluster resonances
3-3. Linear chain in n-rich C
Cluster resonances
Kuchera et al.
Ito et al.
Kobayashi et al.
0+
Freer PRL.82(99)(06)
Saito NPA738 (04)
Yang PRL112 (14）
6He+4He
3,4?
0+
a
a
6,8He+6,4He
a
a
+
03
Exotic cluster res. also suggested
8He+6He in 14Be
Ito et al. Y. K-E et al.
9Li+6He in 15B
6He+3H
a
2
a
a
Cluster res. ?
MO bond
0+2
aa
K=0+1
t
aa
Normal
10Be
a
0+1
a
12Be
MO bond ?
at
9Li
6He+3H
cluster resonances in 9Li
9Li:
energy
levels(calculation)
Y. K-E. et al
PRC.85(12)
MeV
5
5/21/2- 3/2-
0
6He+3H
7/2K=1/2- band
6He+3H
threshold
J(J+1)
resonance
a
t
9Li(3/2 -)
3
-5
-10
3/2g.s.
9Li
at
9Li(gs)
Cluster structures in
Cluster resonances
a
a K=0+3,4?
6He
a a
9Li
and
t decoupling
K=1/2a
t
(3/2-3)
6He
NO MO bond
MO bond
a t
K=0+2
a
aa
10Be
a
a
10Be
K=0+1
3/2-1
at
t
9Li
g.s(3/2-1)
3-1. MO bond in n-rich Be
& vanishing of magic number
3-2. Cluster resonances
3-3. Linear chain in n-rich C
Linear chain state in 14C*
Neutron-rich
12C
12C* not linear
03+
14C
14,16C
AMD by T.Suhara and Y.K-E,
Phys.Rev.C82:044301,2010.
3a linear chain
proton
14C*,16C*
neutron
Y.K-E.et al.,
T. Neff et al.
Linear chain?
Tohsaki et al.,
Funaki et al.
Energy (Mev)
+
02
von Oertzen ZPA354(96)
EPJA21(04),PR 432(06)
Itagaki PRC64(01)
Suhara PRC82(10)
Maruhn NPA833(10)
+
12C
g.s.
14C
g.s.
14C
Linear chain in n-rich C
Meta stable
for bending motion
Stretching effect
in rotation
AMD by Y.K-E,
PR432(2006)
15C*(19/2-)
 MO model for 14,16C
b=0.78
Itagaki et al. PRC64(01)
 HF calc. for
16,20C
by Maruhn et al. NPA833(10)
11Be+a
suggested
to be a
yrast state
Largely deformed 11Be
with MO-bond
4. Summary
Summary
Rich cluster phenomena in n-rich nuclei
 MO bond & breaking of N=8 shell
 Cluster resonances
 Linear chain
Cluster formation, development, and valence neutrons
play important roles in nuclear structure.
Extended
Ikeda diagram?
by von Oertzen et al
Ikeda et al.PTP464-S (1968)
Taken from Phys. Report 432 (2006)
Many-body correlations at low density
Information of many-body correlations in low density, in isospin asymmetric systems.
Cluster gas, chain ?
Dineutron correlation ?
Nuclear matter
Neutron matter
Matsuo et al. PRC73 044309 (‘06)
a-cond.
in low density
12C(0+ )
α
2
α α
16O*
14-20C*
α
Dilute acluster gas
Unbound
BEC-BCS
Geometric
（crystal ？）
α
α
α
α α
Dineutron at surface of
neutron-rich nuclei
BCS
Systematic study in a wide region
Excitation energy
Low density
multidimension
* proton number
* neutron number
* excitation energy
* density
Neutron number