Reaction dynamics of slow collisions in light neutron excess systems - - PowerPoint PPT Presentation
Reaction dynamics of slow collisions in light neutron excess systems Unified studies from bounds to continuum in Be isotopes I. Introduction II. Framework III.
Reaction dynamics of slow collisions in light neutron excess systems 伊藤 誠
関西大学 システム理工学部 物理応用物理学科
－Unified studies from bounds to continuum in Be isotopes
V. Summary and feature plan
Molecular structures will appear close to the respective cluster threshold. α‐Particle ⇒ Stable Systematic Appearance
cluster structures
3H+p ～ 20 MeV
Cluster structures in 4N nuclei
IKEDA Diagram
Ikeda’s Threshold rules
Be isotopes Molecular Orbital : Itagaki et al., Abe et al,….
― +
PRC61,62 (2000)
Studies on Exotic Nuclear Systems in (Ex ,N, Z,J) Space
( N,Z ) : Two Dimensions
Structural Change Low‐lying Molecular Orbital :
―、＋‥
Unbound Nuclear Systems Slow RI beam Decays in Continuum Is Threshold Rule valid ?? N
Systematics of 8～
16Be
Interests from the viewpoints of large amplitude collective motions Breakup Scattering
Reactions are extreme limits of large amplitude collective motions !
How to characterize … Binary states Combined states Reaction path in adiabatic energy surfaces (AESs) Subjects
connection to AESs structures
Today’s report
Extension of microscopic cluster model (Test calculation for 10Be)
Unified model between M.O. and He clusters :PLB588 (04)
C1 C2 C3
0Pi (i=x,y,z) Coupled channels with Atomic orbitals
6He
Decay widh PTP113 (05) +6He Cross sections PLB636 (06)
10Be=++N+N
ｰi W(R)
S, Ci
: Variational PRM.
S
5He 5He
Combine Absorbing B.C. Scattering B.C.
10Be
→ +6He Breakup
< | | >
4 8 12 −8 −4 4 8 Energy ( MeV ) α − α α − α α − α α − α Distance ( fm )
Femto Molecules ：12Be=++4N
7He 5He 6He 8He 6He
Ionic Ionic Atomic 01
+
02
+
Neutrons’ ex. (‐)2(‐)2 (‐)2 (+)2
(0pR )(0pL) (+)2
05
+
03
+
04
+
06
+
+8He ⇒ 6He+6He Covalent
6He + 6He
+ 8He Clusters’ Relative ex. Various structures are generated by excitation
and neutron degree
−8 −4 4 8
Energy ( MeV )
2 1 − Re Sel −8 −4 4 8
Energy ( MeV )
2 1 − Re Sel −8 −4 4 8
Energy ( MeV )
2 1 − Re Sel −8 −4 4 8
Energy ( MeV )
2 1 − Re Sel −8 −4 4 8
Energy ( MeV )
2 1 − Re Sel
Be isotopes from bounds to continuums : J = 0+
8Be 10Be 12Be 14Be 16Be
Deformed states (Clusters) Compact states (Shell model) Excitation of ‐rel. motion
xHe yHe
Global behaviors of Level Crossings in Be isotopes
Core‐Core distance Large Small
A + B C + D E + F* E + F
Energy Compact ( Normal ) Clusters ( Intruder ) Internal States Asymptotic States Level Crossing
2 4 6 8 10 12 −10 10 20 α − α Distance ( fm ) Excitation Energy ( MeV ) 4He + 6He 2 4 6 8 10 12 −10 10 20 6He + 8He Excitation Energy ( MeV ) α − α Distance ( fm )
+ 6Heg.s.
8Heg.s.
+ 6Heg.s.
10Be 14Be
Level Crossings in 12,14Be=++XN (X=2,6) (0p)2 (sd)2 (0p)4(sd)2 (0p)2(sd)4
Level Crossing Level Crossing
4 8 12 −10 10 20 α − α Distance ( fm ) Excitation Energy ( MeV ) Adiabatic energy surfaces (JP = 0+ ) 4He + 6Heg.s. ( π ( π ( π ( π1/2
1/2 1/2 1/2 − − − − )
) ) )2
2 2 2
( π ( π ( π ( π3/2
3/2 3/2 3/2 − − − − )
) ) )2
2 2 2
( σ ( σ ( σ ( σ1/2
1/2 1/2 1/2 + + + + )
) ) )2
2 2 2
Weak Coupling
4 8 12 −10 10 20 α − α Distance ( fm ) Excitation Energy ( MeV ) Adiabatic energy surfaces (JP = 0+ ) 4He + 6Heg.s. ( π ( π ( π ( π1/2
1/2 1/2 1/2 − − − − )
) ) )2
2 2 2
( π ( π ( π ( π3/2
3/2 3/2 3/2 − − − − )
) ) )2
2 2 2
( σ ( σ ( σ ( σ1/2
1/2 1/2 1/2 + + + + )
) ) )2
2 2 2
α α α α + 6He(21
+)
Adiabatic surfaces (J= 0+) Energy spectra ( J= 0+ )
ｰi W(R)
+6He(21
+)
10Be (0+) case : M.I., PLB636, 236 (2006)
Cluster
S‐matrices to continuums
4 8 12 16 0.001 0.002 Decay energy ( MeV ) Psude states <− ground state | Sf<−i |2 1st Peak ( Single ) 2nd Peak ( Coherent ) 4He + 6He(21
+) Cluster
(π1/2
−)2
4 8 12 16 0.25 0.5 Decay energy ( MeV ) Pole contribution in decays to 4He+6He(21
+)
| Sf<−i |2 4He + 6He(21
+) Cluster
(π1/2
−)2
Smat.( Poles ← G.S.) Smat.( Conti.←G.S. )
Nuclea breakup : 10Be +12C ⇒ 10Be(0+ conti.) + 12C (CDCC cal.)
S‐matrices to Poles
03
+
04
+
04
+
03
+
4 8 12 −10 10 20 α − α Distance ( fm ) Excitation Energy ( MeV ) Adiabatic energy surfaces (JP = 0+ ) 4He + 6Heg.s. ( π ( π ( π ( π3/2
3/2 3/2 3/2 − − − − )
) ) )2
2 2 2
4He + 6He(21
+)
4 8 12 −10 10 20 α − α Distance ( fm ) Excitation Energy ( MeV ) Adiabatic energy surfaces (JP = 0+ ) 4He + 6Heg.s. α α α α + 6He(21
+)
4He + 6He(21
+)
Non‐adiabatic path is main process.
4 8 12 −10 10 20 α − α Distance ( fm ) Excitation Energy ( MeV ) Adiabatic energy surfaces (JP = 0+ ) 4He + 6Heg.s. ( π ( π ( π ( π1/2
1/2 1/2 1/2 − − − − )
) ) )2
2 2 2
( π ( π ( π ( π3/2
3/2 3/2 3/2 − − − − )
) ) )2
2 2 2
( σ ( σ ( σ ( σ1/2
1/2 1/2 1/2 + + + + )
) ) )2
2 2 2
Weak Coupling
Reaction path in 10Be → xHe + yHe Breakup reaction (Positive Parity)
01
+
03
+
01
+
→ 03
+
is the dominant transition.
10Be(0+) → [
+ 6He(21
+) ] 0+
Reaction Path in Breakup
4 8 12 10 20 α − α Distance ( fm ) Excitation Energy ( MeV ) Adiabatic energy surfaces (JP = 1− ) ( π ( π ( π ( π3/2
3/2 3/2 3/2 − − − − σ
σ σ σ1/2
1/2 1/2 1/2 + + + + )
) ) ) [ α [ α [ α [ α + 6Heg.s. ] [ α [ α [ α [ α + 6He(21
+) ]
α α α α + 6Heg.s.
+6He(01
+) → +6He(21 +) 4 8 12 10 20 α − α Distance ( fm ) Excitation Energy ( MeV ) Adiabatic energy surfaces (JP = 1− ) 4He + 6Heg.s.
+6Heg.s. + 6Heg.s. ⇒ +6He(21
+) scattering (Negative Parity)
Avoided crossing at the surface Landau‐Zener type enhancement
2 3 4 5 6 7 8 9 10 −10 10 Distance ( fm )
Energy ( MeV )
2 3 4 5 6 7 8 9 10 −10 10 Distance ( fm )
Energy ( MeV )
Level Crossing in 12Be (1)
(‐)2 (+)2 (‐)2 (‐)2 + 8Heg.s. + 8Heg.s. (‐)2 (+)2 (‐)2 (‐)2
+
(‐)2 (+)2 + 8Heg.s.
+
S=1 corr.
Un correlated AESs Correlated AESs
Two AESs are almost degenerated due to correlations ⇒ Crossing occurs at inner region !
2 3 4 5 6 7 8 9 10 −10 10 Distance ( fm )
Energy ( MeV )
2 3 4 5 6 7 8 9 10 −10 10 Distance ( fm )
Energy ( MeV )
Level Crossing in 12Be (2) Correlated AESs AESs with full coupling
Coupling with all configurations Lowest minimum smoothly connected to +8He g.s. ⇒ Formation of adiabatic conjunction Conjunction G.S.⇔ +8He + 8Heg.s. G.S.
−8 −4 4 8
Energy ( MeV )
6He + 6He 5He + 7He 4He + 8He
Monopole transition of 12Be
1 1 2 0
) , (
A i i f
r IS E M
2
) , ( IS E M
Adiabatic conjunction enhances the monopole transition !
2 3 4 5 6 7 8 −8 −4 4 8 Distance ( fm )
Energy ( MeV ) (‐)2 (+)2
8He
01
+
03
+
01
+ → 03 +
is enhanced.
Contents of present report Results
Feature studies
Extension to SD shell ⇒ O=+12C+XN、Ne=+16O+XN Generalities and Specialities : hybrid structures of clusters + excess neutrons in O and Ne
2. Reactions with large amplitudes in connection to adiabatic energy surfaces
N)
10Be : Non‐adiabatic path is dominant in monopole breakup and slow scattering. 12Be : Adiabatic path is dominant in monopole b.u. (Formation of conjunction)
Recently, we have just succeeded in extending the model to general two centers.
Systematics based on the Cluster Picture
10Be 14Be
R:(0P3/2 )2
L:(0P3/2 )－4 R:(0P3/2)－2 L:(0P3/2)4
8Be 16Be
R:(0P3/2 )－4
L:(0P3/2 )－4 R:(0P3/2)4 L:(0P3/2)4 Similar Similar
Special feature in 12Be
12Be=6He+6He, +8He
is a self conjugate when atomic p‐h are exchanged. ⇒ This is a special nucleus in even Be isotopes We are now analyzing wave functions.
4 8 12 −10 10 20 α − α Distance ( fm ) Excitation Energy ( MeV ) Adiabatic energy surfaces (JP = 0+ ) 4He + 6Heg.s. ( π ( π ( π ( π1/2
1/2 1/2 1/2 − − − − )
) ) )2
2 2 2
( π ( π ( π ( π3/2
3/2 3/2 3/2 − − − − )
) ) )2
2 2 2
( σ ( σ ( σ ( σ1/2
1/2 1/2 1/2 + + + + )
) ) )2
2 2 2
Weak Coupling
4 8 12 −10 10 20 α − α Distance ( fm ) Excitation Energy ( MeV ) Adiabatic energy surfaces (JP = 0+ ) 4He + 6Heg.s. ( π ( π ( π ( π1/2
1/2 1/2 1/2 − − − − )
) ) )2
2 2 2
( π ( π ( π ( π3/2
3/2 3/2 3/2 − − − − )
) ) )2
2 2 2
( σ ( σ ( σ ( σ1/2
1/2 1/2 1/2 + + + + )
) ) )2
2 2 2
α α α α + 6He(21
+)
Adiabatic surfaces (J = 0+) Energy spectra ( J = 0+ )
ｰi W(R)
+6He(21
+)
GTCM + Absorbing Boundary Condition : PLB (2006)