Nuclear Structure, Weak-induced Reactions and Nucleosynthesis

Toshio Suzuki Nihon University

NAOJ-RIKEN

Oct. 17, 2012

・ New shell-model Hamiltonians and successful description of

Gamow-Teller (GT) and spin-dipole (SD) strengths

SFO (p-shell): GT in 12C, 14C 　　 Suzuki, Fujimoto, Otsuka, PR C69, (2003) CK+MK+ monopole corrections in spin-isospin-flip 2BME

SFO-tls (p-sd shell): SD in 16O Suzuki, Otsuka, PR C78, (2008) SFO + (π+ρ)-tensor in p-sd cross shell interaction

GXPF1J (fp-shell): GT in Ni isotopes Honma, Otsuka, Mizusaki, Brown, PR C65 (2002); C69 (2004)

Suzuki, Honma et al., PR C79, (2009)

VMU (monopole-based universal interaction)

＊ important roles of tensor force

tensor force

G-matrix vs phenom. interactions

more repulsion than G in T=1more attraction than G in T=0Three-body force

○ Electron capture reactions in stellar environments ・ e-capture rates on 56Ni, 58Ni and 60Ni ・ synthesis of 56Ni, 58Ni in type-Ia supernovae

○ ν-nucleus reactions ・ ν-12C and synthesis of 11B in supernova

explosions ・ ν-13C by solar neutrinos ・ ν-16O reactions ・ ν-56Ni and synthesis of Mn in supernova

explosions

○ β-decays of waiting-point nuclei at N=126 and r-process nucleosynthesis

● Important roles of tensor force

・ SFO: p-shell p-sd space up to 2-3 hw excitations CK-MK (p: Cohen-Kurath, p-sd: MK, sd: G-matrix) → Enhancement of spin-isospin channel of monopole terms

Monopole terms 1 2 1 2T JM 1 2

J

(2J 1) j j ;JT | V | j j ;JTV ( j j )

(2J 1)

p1/2-p3/2 (T=0) is enhanced

B(GT) values for 12C -> 12N

present = SFO Suzuki, Fujimoto, Otsuka, PR C67 (2003)

Magnetic moments of p-shell nuclei

KVIRCNP

Negret et al., PRL 97 (2006)

B(GT) values for 14N -> 14C

SFO

SFO*: gAeff/gA=0.95

B(GT: 12C)_cal =experiment

SFO

Space: up to 2-3 hw

Shell evolution inN=8 isotones N=20 isotones

N=8

N=6

πp3/2

Change of magic number N=8 → N=6 N=20 → N=16

20

16

SFO p-sd shell Suzuki, Fujimoto, Otsuka, PR C67, 044032 (2003)

PR C55, 2078 (1997)

Nucleosynthesis processes of light elements

4 3

4 3

He( , 'p) H

He( , 'n) He

12 11

12 11

C( , 'p) B

C( , 'n) C

GT stengths in 12C: reproduced with gAeff/gA=0.95

Nearly vanishing GT strength in 14C

Enhancement of 11B and7Li abundances in supernova explosions

Effects of contamination of 13C on inclusive ν-12C reaction cross sections 12C 98.9% 13C 1.1%12C (ν, e-) 12Ng.s. ΔM =16.83 MeV13C (ν, e-) 13Ng.s. ΔM = 1.71 MeV 　　→　　　 σ(13C) > σ(12C)

Below Eν = 15 MeV: pure ν-13C reactions No contamination from ν-12C reactions

13C: attractive target for very low energy νν-induced reactions on 13C

C'),(C

N)e,(C13

ee13

13e

13

GT transitions

Fukugita et al., PR C41 (1990)p-shell: Cohen-KurathgA

eff/gA =0.69

Detector for solar ν

GT

GT

GT+IAS

p-sd shell: SFOSolar ν cross sectionsfolded over 8B ν spectrum

243

243

242

242

e

cm1023.2:SFO

cm1016.1:CK

)MeV69.3(2

3)',(

cm1034.1:SFO

cm1007.1:CK

)]MeV50.3(2

3.)s.g(

2

1[)e,(

Suzuki, Balantekin, Kajino, PR C 86, 015502 (2012).

○ New shell-model Hamiltonians in fp-shell: GXPF1: Honma et al., PR C65 (2002); C69 (2004) KB3: Caurier et al., Rev. Mod. Phys. 77, 427 (2005) ○ KB3G A = 47-52 KB + monopole corrections ○ GXPF1 A = 47-66 ・ Spin properties of fp-shell nuclei are well described

B(GT-) for 58Ni

Fujita et al.

gAeff/gA

free=0.74

8-13MeV

M1 strength(GXPF1J)

gSeff/gS=0.75±0.2

7 10 3e

99

Y 10 10 g / cm

T T 10 K

2

2 2 2

99

3 22

0

2

6146

110

1

1

ej j ej

j p d j e

e ee e

ee e p p e

A

lnB (GT ) p(Q ) F( Z , )S ( )d

( s )

Q ( M c M c E ) / m c

T T K , S ( E )exp[( E ) / kT ]

m cY ( ) ( S S )p dp

N

●Electron-capture rate in steller environment

1

1

1

0Z Z

Z Z

Z Z

e A A

T : M( A) M( A)

M( A) M( A)

Sasano et al.PRL 107, 202501 (2011)

f7/2 -> f5/2

f7/2 -> f7/2f7/2 -> f5/2

e-capture rates in stellar environments

7 10 3e

99

Y 10 10 g / cm

T T 10 K

ρYe=109

108

107

Sasano et al.

● preliminary

58Ni → 58Co

Exp: Hagemann et al., PL B579 (2004)60Ni → 60Co

Exp: Anantaraman et al., PR C78 (2008)

Type-Ia supernova explosion

Accretion of matter to white-dwarf from binary star → supernova explosion when white-dwarf mass is over Chandrasekhar limit → 56Ni (N=Z) → 56Ni (e-, ν) 56Co Ye =0.5 → Ye < 0.5 (neutron-rich) → production of neutron-rich isotopes; more 58Ni Decrease of e-capture rate on 56Ni → less production of 58Ni.

e-capture rates:GXPF1J < KB3G←→ 　Ye (GXPF1J) > Ye (KB3G)

Famiano

Problem of over-production of 58Ni

Famiano

●Neutral current reaction on 56NiB(GT)=6.2 (GXPF1J) B(GT)=5.4 (KB3G)

cf: HW02gammapn

59 58 59 59 59Co : Ni(p, ) Cu(e , ) Ni(e , ) Co

Suzuki et al.,PR C79 (2009)

OBS: Cayrel et al.,Astron. Astrophys.416 (2004)

Yoshida, Umeda, Nomoto

56 55 55 55 55Ni( , 'p) Co, Co(e , ) Fe(e , ) Mn

Synthesis of Mn in Population III Star

54 55Fe(p, ) Co

R-Process Nucleosynthesis and Beta Decays of N=126 Isotones

Focus on the 3rd

peak region

Waiting point nuclei

∑B(GT)=14.4 ∑B(GT)=14.6

∑B(GT)=11.7 ∑B(GT)=8.5 ∑B(GT)=5.6

Q=gAeff/

gA=0.7

Ex=0 ←→ g.s. of the parent nuclei

GT strengths

gAeff/gA=0.7

E=0: g.s. of the parent nuclei

SD+E1 (1-) strengths spin part only

Q=gAeff/gA=0.7

Moller, Pfeiffer, Kratz, PR C 67, 055802 (2003)

cf.

Q=gAeff/gA=0.7, ε=2.0 (0-)

Shell Model calculations

Neumann-Cosel et al, PRL 82 (1999)Q=gs

eff/gs=0.64: 2- in 90Zr (e-scatt.)

r-process nucleosynthesis

Constant Entropy Wind ModelLν=0.5x1051 erg/sS=133 kB (γ, e-, e+)

dm/dt=2.34x10-6 Msun

τ= 5.60 ms for T9=5 ->T9=2T9f=0.8

Neutrino processes on n, pand 4He are included

Half-lives:Standard (Moller et al.)Modified

gAeff/gA =0.34, gV

eff/gV =0.67

+ ΔQ =1.0 MeV

Large quenchings are favored in A =206(gA

eff/gA,gVeff/gV)=(0.34,0.67),

(0.51, 0.30), (0.47, 0.64)Warburton, PR C 44, 233 (1991) PR C42, 2479 (1990)Rydstrom, NP A512, 217 (1990)

Dependence on (gAeff/gA, gV

eff/gV ）

Exp: Benlliure et al.

Summary

• A new shell model Hamiltonian SFO well describes the spin responses in p-shell and p-sd shell nuclei → new GT (SD) strengths in C isotopes (16O) and new ν-12C, 13C and ν-16O cross sections

• A new shell model Hamiltonian GXPF1J well describes the spin responses in fp-shell niclei → new GT strengths in Ni isotopes which reproduce recent experimental data

• Electron capture rates in 56Ni, 58Ni and 60Ni are well described by GXPF1J.

　　 Suzuki, Honma, Mao, Otsuka, Kajino, PR C83, 044619 (2011)

　→ Abundance ratio of 58Ni/56Ni in type Ia 　 supernova explosions is improved

・ New ν-nucleus reaction cross sections in 56Ni → 　　 enhancement of production rates of Mn and Co in supernova explosions Suzuki, Honma et al., PR C79, 061603(R) (2009)

・ Short half-lives for beta decays of N=126 isotones 　　 compared to a standard model (FRDM) → The 3rd peak of the r-process element abundances is shifted toward larger mass number region. 　　 Suzuki, Yoshida, Kajino, Otsuka, PR C85, 015802 (2012)

Collaborators

M. Honmaa, T. Yoshidab, S. Chibac, H. Maod, K. Higashiyamae, T. Kajinob,f, T. Otsukag

B. Balantekinh, T. Umedab, K. Nomotob,i, Famianof,j

aUniversity of Aizu bDepartment of Astronomy, University of Tokyo cTokyo Institute of Technology dENSPS, Strasbourg eChiba Institute of Technology fNational Astronomical Observatory of Japan gDepartment of Physics and CNS, University of Tokyo hUniversity of Wisconsin iIPMU, jRIKEN