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Gamow-Teller Transitions for Light Nuclei by the Deformed Quasi-particle RPA(DQRPA)

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Gamow-Teller Transitions for Light Nuclei by the Deformed Quasi-particle RPA(DQRPA)

Soongsil University, Korea

Eun Ja HA and Myung-Ki CHEOUN

2011 HNP

- Motivation
- Formalism
- Deformed basis (Nilsson basis)

- Deformed Bardeen Cooper Schrieffer (DBCS)

- Deformed quasi-particle random phase approximation (DQRPA)

- Gamow-Teller transitions for the nuclear beta decay

- Results
- Summary

2011 HNP

Motivations

Formalism

Results

Summary

～3hours

Supernovae Type II

X-ray and Super Burst

Time scale ： ～ a few hours

Total energy : 1042 erg (normal burst ~ 1039 erg)

2014-08-21

SKKU, 17 June. 2010

31

2011 HNP

Motivations

Formalism

Results

Summary

Pycno‐reaction (Haensel & Zdunik1990 )

Because of high density and low temperature on the neutron star crust,Coulomb barrier is overcome by the zero-point motion of the nuclei in the solid lattice !!

Degenerated electrons block the beta decay. Ordinary nuclei become highly unstable, and unstable nuclei become the normal stable nuclei at the neutron-star crusts !!

2014-08-21

SKKU, 17 June. 2010

41

4

2011 HNP

Motivations

Formalism

Results

Summary

- The conventional approach so far to understand the nuclear structure is based on the spherical symmetry.

spherical basis deformation np-pairing correlation

Considering nuclear deformation and np-pairing correlations will modify the occupation probabilities.

The Gamow-Teller transition as well as other transition also will be affected.

2011 HNP

Motivations

Formalism

Results

Summary

We extend our previous QRPA based on the spherical symmetry, which turns out to be a very useful tool for relevant reactions in the nuclear-astrophysics.

2011 HNP

Motivations

Formalism

Results

Summary

Formalism

Deformed WS

Deformed BCS

Deformed QRPA

Gamow-Teller transition

Without np-pairing

With np-pairing(in progress)

Realistic two body interaction

taken by Brueckner G-matrix

based on the Bonn potential

2011 HNP

Motivations

Formalism

Results

Summary

Axially symmetric harmonic oscillator w.f.

- The single particle states

Spin w.f

2011 HNP

Motivations

Formalism

Results

Summary

Spherical harmonic oscillator w. f.

- The deformed basis(Nilsson basis) is expanded

By Including deformation

2011 HNP

Motivations

Formalism

Results

Summary

Deformed BCSIn order to renormalize the G-matrix, theoretical values are adjusted to the empirical pairing potentials by multiplying the G-matrix with a strength parameters gpp(gnn).

By Including deformation

by a symmetric five term formula

2011 HNP

Motivations

Formalism

Results

Summary

Description of Intermediate States

for Gamow-Teller excitation K=1,0,-1

DQRPA equation

2011 HNP

Motivations

Formalism

Results

Summary

Realistic two body interaction taken by Brueckner G-matrix

based on the Bonn potential

By Including deformation

particle-particle

particle-hole

2011 HNP

Motivations

Formalism

Results

Summary

2011 HNP

Motivations

Formalism

Formalism

Results

Results

Summary

Summary

Ikeda sum rule

in percentage of 3(N-Z)

2011 HNP

Motivations

Formalism

Formalism

Results

Results

Summary

Summary

Experiment

by Madey (1987)

Gamow-Teller

Strength in 26Mg

2011 HNP

Motivations

Formalism

Formalism

Results

Results

Summary

Summary

Ours

60Ni (p,n) 60Cu

Experiment

60Ni (n,p) 60Co

Gamow-Teller

Strength in 60Ni

2011 HNP

Motivations

Formalism

Formalism

Results

Results

Summary

Summary

Gamow-Teller strength in 76Ge

Calculatiion by Fedor.

Experiment

2011 HNP

Motivations

Formalism

Results

Summary

Summary

1. To describe a single particle state in deformed basis, we

used the deformed axially symmetric Woods-Saxon potential.

And then we performed the deformed BCS and deformed QRPA with realistic two-body interaction calculated by Brueckner G-matrix based on Bonn potential.

2. We calculated the Gamow-Teller transitions in 26Mg , 60Ni, and 76Ge. Our results are reproduced well the position of energy with available experimental data and other calculations but we have some problem for the B(GT) strength.

3. We are checking transition operator and np-pairing correlations to improve the B(GT) strength.

2011 HNP

Future works

1. Next stage is E1 and E2 transitions in unstable nuclei to study the inversion island, which comes from the shell evolution sensitive to the deformation .

2. Weak interactions with unstable nuclei by the neutrino, in specific, stemmed from the supernova explosion are also one of the interesting topics, because relevant cross sections are believed to differ from those in stable nuclei and affect rapid processes in the nucleosynthesis on the corecollapsing supernovae and/or the crust of the neutron star with a binary star.

2011 HNP

2011 HNP