Unified studies of light neutron-excess systems from bounds to continuum

Unified studies of light neutron-excess systemsfrom bounds to continuum

Makoto Ito Department of Pure and Applied Physics, Kansai University

I. Introduction

II. Framework

III. Various structures in 12Be and Be isotopes

－ Structural changes and Reaction dynamics in Be isotopes －

V. Summary and feature plan

IV. Enhancements induced by level crossing

Molecular structures will appear close to the respective cluster threshold.

α-Particle building block⇒

Clustering phenomena is generated by a huge mixing of shell model configuration.

3H+p ～ 20 MeV

Cluster structures in 4N nuclei IKEDA Diagram

Ikeda’s Threshold rules

Be isotopes

Molecular Orbital : Itagaki et al,….

p―

s +

PRC61,62 (2000)

H.O. quanta N

<N> ± DN

～ 34.6 ± 5.9

Studies on Exotic Nuclear Systems in (Ex,N, Z,J) Space

( N,Z ) : Two Dimensions

Ex. e

nerg

yStructuralChangeLow-lying

Molecular Orbital : p ― 、 s ＋‥

Unbound Nuclear SystemsSlow RI beam

Decays inContinuum

Is Threshold Rule valid ??

N

1. Structures of 8 ～ 16Be2. Breakup of 10,12Be

Extension of microscopic cluster model (Test calculation for 10Be)

Unified model between M.O. and He clusters :PLB588 (04)

+ + ...

C1 C2 C3 =Y

0Pi (i=x,y,z) Coupled channels with Atomic orbitals

Mol. Orb. a 6He

Decay widhPTP113 (05)

a+6He Cross sectionsPLB636 (06)

10Be=a+a+N+N

ｰ i W(R)

S, Ci : Variational PRM.

S

5He 5HeCombine

Absorbing B.C. Scattering B.C. Tr. densites

10Be → a+6HeBreakup

<CL | r| MO>

Femto Molecules ： 12Be=a+a+4N7He5He

6He

8He

6He

Ionic

Ionic

Atomic

01+

02+

Neutrons’ ex.

(p-)2(p-)2

(p-)2 (s+)2

(0pR)(0pL) (s+)2

05+

03+

04+

06+

a+8He ⇒ 6He+6HeCovalent

6He + 6He

a + 8He

Clusters’Relative ex.

Various structures are generated by excitation of a-a and neutron degree of freedom.

NN: Volkov No.2+G3RS

Be isotopes from bounds to continuums : Jp = 0+

8Be 10Be 12Be 14Be 16Be

Deformed states (Clusters)

Compact states (Shell model)Excitation of a- a rel. motion

xHe yHe

Level Crossings scheme in Be isotopes

Core-Core distance LargeSmall

A + B

C + D

Ener

gy

Compact( Normal )

Clusters( Intruder )

Internal States

AsymptoticStates

Level Crossing

We can discuss reaction dynamics inconnection to level crossing scheme.

a + 6Heg.s. 8Heg.s. + 6Heg.s.

10Be 14Be

Level Crossings in 12,14Be=a+a+XN (X=2,6)

(0p)2

(sd)2

(0p)4(sd)2

(0p)2(sd)4

Level Crossing

Level Crossing

Adiabatic surfaces (J p = 0+) Energy spectra ( J p = 0+ )

ｰ i W(R)

a+6He(21+)

GTCM + Absorbing Boundary Condition : PLB (2006)

Cluster

S-matrices to continuums

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+

Non-adiabatic tr. is main process.

Reaction path in 10Be → xHe + yHe Breakup reaction (Positive Parity)

×

01+

03+

01+ → 03

+ is the dominant transition.

10Be(0+) → [ a + 6He(21+) ] 0+ Reaction Path in Breakup

Level Crossing in 12Be (2) : breaking of N=8 magic number and level crossing

Correlated AESs AESs with full coupling

Coupling with all configurations

Lowest minimum smoothly connected to a+8He g.s. ⇒ Formation of adiabatic conjunction

Conjunction G.S. ⇔ a+8He

a + 8Heg.s.

G.S.

(p-)2 (s+)2

(p-)2 (p-)2

a + 8Heg.s.

[(0p)6] [(0p)4(sd)2]

Correlation

Monopole transition of 12Be

11

2 00),0(A

iif rISEM 2

),0( ISEM

Adiabatic transition is main process in monopole transition.

(p-)2 (s+)2

8He

01+

03+

01+ → 03

+ is enhanced.

Contents of present report

Results

1. Unified studies form bounds to continuums in Be isotopes

Feature studies

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

2. Reactions with large amplitudes in connection to adiabatic energy surfaces

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).

Recently, we have just succeeded in extending the model to general two centers.