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Y. Kanada-En’yo (YITP, Kyoto Univ.)M. Kimura (Tsukuba)Y. Taniguchi (Kyoto Univ.)
Cluster aspect of light unstable nucleiCluster aspect of light unstable nuclei
1. Introduction
new-typeclustering
coexistence of cluster & mean-field
Cluster physics
1930’sBethe et al.
Weakly Interacting
-particles
Meyer & Jensen, shell structure, mean-field
1949
1960’s 1970-80’sCluster & scattering
microscopic cluster models
(RGM,OCM,GCM)
Very light nuclei (A<8)
multi
non-(N, t, 12C, 16O) clusters
p-shell, sd-shellnuclei
molecular resonances16O+16O etc.
1990’s-Clustering in
unstable nuclei
Unstable nuclei
sd, pf-shellinnovative models (GCM,MO.SVM,AMD,..)
n
2H1H
3He 4He3H
6Li 7Li
9Be
6He
8Li8He
8Be7Be 10Be9Li
11Be12Be11Li
10B 11B 12B 13B 14B 15B14Be
9B8B
12C 13C 14C 15C 16C 17C 18C 19C 20C17B 19B
11C10C9C8C
14N 15N 16N 17N 18N 19N 20N 21N13N12N11N
12O 13O 14O 15O 16O 17O 18O 19O 20O 21O 22O
core
core
neutron halo
neutron skin
Decoupling of Proton and neutrons
α α
α α
molecular
α
α
α
dilute gas
α
α α
0+2 in 12C
6He,11Li,11Be
8He,CBe isotopes
10C, 16C
3-2 in 14C
triangle
excited states
He
Li
Be
B
C
H
structure in light nuclei
vanishing of magic number
sd-shellExploring concept of cluster:
Spatial correlation of multi nucleons
Typical clustering in stable nuclei
α α8Be
ααα
12C
16O α20Ne
12C α16O*
Conventional cluster structure
Weak coupling picture: Cluters are formed by tightly bound nucleons.
Weakly coupled inter-cluster motion is considered.
Exploring concept of clustering (1)
halo nuclei: 6He, 11LiA.Tosaka et al.,S. Aoyama et al.
correlation
K.Varga et al.,
2n
di-neutron core-n
V-type T-type
Ne, O isotopes
6He+6He in 12Be
2-coreneutron orbit
α α
α α
Seya, Von Oerzten, Descouvemont et al.,Itagaki et al., K-E et al.M. Ito et al.
16O
Molecular structures
neutron-rich Be isotopesEsbensen et al.,Hagino et al.Descouvemont et al.
Valence neutrons play important roles Yoshida et al.,
Kimura et al.Furutachi et al.
-cluster gas
Tohsaki et al., Yamada et al.,Funaki et al. Wakasa et al.,
12C(02 )+
α
α
α
Dilute 3Dilute 3gas gas
16O*
Exploring concept of clustering (2)
Itagaki et al.,Von Oertzen et al.
α
α
α
14C*(3-2)
cluster crystalization
-condensation
BEC-BCS
dineutron-cond.
αα α
Price et al.
12,14,15,16C* linear chain
triangle
Roepche et al.
Nuclear matter
matsuo et al.
Exploring concept of clustering (3)
Superdeformation & cluster
16O 16O 32S+ SD
Cluster excitation
Molecular states.16O 16O
Coexistence of cluster & mean-field
Heavier nuclear region
α
α
α
Z=N nuclei: 32S, 40Ca
nucleon correlation at surface
Itagaki et al.
Kimura et al., taniguchi et al.
Contribution of cluster aspects
Physics:
Halo nuclei,
Breaking of magicity
Molecular, deformation,
new cluster states
Methods:
less assumption, ab-initio calc. ,
tensor force, effective nuclear force
resonances & continuum
Contribution to recent developments
Cluster is one of the essential features in nuclear many-body system.
Systematic study focusing on cluster phenomena.Question: what is the mechanism of appearance of clusters ?
2-1. Molecular states: 12Be ,13B
2-2. Cluster gas-like states: 12C, 11B(11C), 8He
2. Topics
2-1. Molecular states: 12Be ,13B
2-1. Molecular states in 12Be,13B
Breaking of magicity (N=8) in 12Be
0+2 (2.24MeV)
+10 intruder state
0
2
Formation of 2+molecular orbitals
--orbitalorbital
±
Deformed ground statewith d-wave componentsExperiments: Iwasaki et al., Navin et al., Pain et all.
20
12Be
+ - +αα2.24 MeV
αα
Bond role
Breaking of N=8 magicityY.Kanada-En’yo et al., PRC 68, 014319 (2003)
Exp.
AMD
positive parity states with normal spins
(a)(b)
(c)
++
Success of AMD for 12Be
Formation of 2+molecular orbitals
VAP calculation with AMD method
0+2 (2.24MeV)
+10 intruder
0
2
α α
12Be
αα
2
0
12Be 13Bone proton
0
2
3
MO states ?
Search for MO states of 13B
α α
Experimental report 4He(12Be,13B)
MeV 5xE12/1
αα
proton intruder configuration
S. Ota et al. jps meetring, Mar 2007
Excited states of 13B studied with AMD
VAP calc. of AMDMV1(m=0.65)+G3RS(ls=3000)
0
5
10
15
20
0 20 40
J (J +1)
Excitation
energy (MeV)
0
5
10
15
20
0 20 40
J (J +1)
Excitation
energy (MeV)
13B(-) 13B(+)
22/3K 12/1K
0
2
3
3
2
12/1
2)()(3 sdsd
+ - +αα
13B(1/2+1)
Present calc.
MeV 8xE73.0
Hyper deformation ?
protonneutron4He(12Be,13B) ExperimentsBy Ota et al.
MeV 5xE12/1
Proton intruder statein neutron-rich nuclei
2
0
0
2
12Be 13B
one proton
22/3K
12/1K
deformed bands with MO structure in 13B
Deformed bands in Ex < 10 MeVMO structure in 13B
Proton intruder state
2-2. Cluster gas-like states: 12C*, 11B*(11C*), 8He*
01+
02+
03, 4+
10.3 MeV
7.65 MeV
3+p3/2closed
+ααα
α α α
12C
8Be+
p3/2
chain ?
α
α
α
Dilute clusterDilute clustergas gas
A.Tohsaki et al., (2001)Funaki et al.(2003)
11C, 11B
13C ,14C
α
α
α
α
16O
αα
αα 16O(0+
5) ?
Bosonic behaviorBosonic behavior
2-2. Cluster gas-like states
Tohsaki et al., Yamada et al.,Funaki et al. Wakasa et al.,
K-E. , Kawabata et
Itagaki, K-E. , Kawabata et
t
11B(11C)
7Li+
2+t
3/21
-
3/22
-
3/23
-3/24
-
8.5
10.3
ααt
α
α
Dilute 2Dilute 2+t+t
p3/2
AMD by Y.K-E.
Mysterious 3/2-3 state:
Weak beta & M1 transitions
Strong E0 transition
01+
02+
7.65 MeV
3+p3/2closed
+ααα
12C
8Be+
p3/2
α
α
α
Dilute 3Dilute 3gas gas
three-center cluster states in three-center cluster states in 1111B and B and 1111CCA candidate in 1111B(B(1111CC)
Kawabata et al. by (d,d’)
Y. K-E. PRC(2006)
t
-condensation
Tohsaki et al., Yamada et al.,Funaki et al.
12C(02 )+
α
α
α
Dilute 3Dilute 3gas gas
16O*
di-neutron in dilute neutron matter
di-neutrons in halo nuclei (6He, 11Li)
V-typeT-type
Aoyama, et al.5, 7H ?
Roepche et al.(1998)
Dineutron gas ?
Matsuo et al.(2006)
T-type
Two dineutrons in 8He
12C
Dilute clusterDilute clustergas gas
8He
8He(01+)
p3/2
ExcitedStates ?
12C(01+)
12C(02+)
V-type
+
6He(01+)
+ααα p3/2
=
=
Possible dineutron gas-like state of 8He
01+
p3/2
8He(02+)
8He AMD+GCM calc. suggestsdineutron gas-like state
AMD+GCMwith effective N-N interactions(MV1, Volkov)
6He+2n
4He+4n
r.m.s.n.r.=3.1 fm
r.m.s.n.r.=2.6 fmMV1 MV1Volkov No.2m=0.58b=h=0
m=0.62b=h=0
m=0.56b=h=0.15
Dineutron structure: analogy to 12C(0Dineutron structure: analogy to 12C(0++22))
(C)
8He(02+)
g.s.
8He(0+2)
nn 2-2-He)0(He 48
)0()0( LL
)(rry
S-fac=0.47
SU(3)-limit
r
r (fm)
12C(02+)g.s.
)0()0(Be8 L
)0(Be)0(C 812
12C(0+2)
)(rry SU(3)-limit
r
r (fm)
Dineutron component at large distance
)0(He6
1. Molecular states: 13B*
2. Dineutron gas-like state: 8He*
AMD(VAP)
AMD(GCM)
3. Summary
Variation in the energy-isospin plane
Unstable
Isospin symmetry
Ex
cita
tio
n e
ne
rgy
Stable
α
α
α
αcondensation
12C
p3/2
p3/2
8He
α
α
DineutronCondensation ?
Breaking of N=8 magicity
α α
MO
α αintruder
12Be13B
αα
Systematic study covering a wide region of the energy-isospin plane is essential to understand nuclear many-body systems