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 12 C, 14 C Suzuki, Fujimoto, Otsuka, PR C69, (2003) CK+MK+ monopole corrections in spin-isospin-flip 2BME SFO-tls (p-sd shell): SD in 16 O 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=1 more attraction than G in T=0 Three-body force

○ Electron capture reactions in stellar environments ・ e-capture rates on 56 Ni, 58 Ni and 60 Ni ・ synthesis of 56 Ni, 58 Ni in type-Ia supernovae ○ ν-nucleus reactions ・ ν- 12 C and synthesis of 11 B in supernova explosions ・ ν- 13 C by solar neutrinos ・ ν- 16 O reactions ・ ν- 56 Ni 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 p1/2-p3/2 (T=0) is enhanced

B(GT) values for 12 C -> 12 N present = SFO Suzuki, Fujimoto, Otsuka, PR C67 (2003) Magnetic moments of p-shell nuclei KVI RCNP Negret et al., PRL 97 (2006) B(GT) values for 14 N -> 14 C SFO SFO*: g A eff /g A =0.95 B(GT: 12 C)_cal =experiment SFO Space: up to 2-3 hw

Shell evolution in N=8 isotones N=20 isotones N=8 N=6 πp3/2 Change of magic number N=8 → N=6 N=20 → N=

SFO p-sd shell Suzuki, Fujimoto, Otsuka, PR C67, (2003) PR C55, 2078 (1997) Nucleosynthesis processes of light elements GT stengths in 12 C: reproduced with g A eff /g A =0.95 Nearly vanishing GT strength in 14 C Enhancement of 11 B and 7 Li abundances in supernova explosions

Effects of contamination of 13 C on inclusive ν- 12 C reaction cross sections 12 C 98.9% 13 C 1.1% 12 C (ν, e - ) 12 Ng.s. ΔM =16.83 MeV 13 C (ν, e - ) 13 Ng.s. ΔM = 1.71 MeV → σ( 13 C) > σ( 12 C) Below E ν = 15 MeV: pure ν- 13 C reactions No contamination from ν- 12 C reactions

13 C: attractive target for very low energy ν ν-induced reactions on 13 C GT transitions Fukugita et al., PR C41 (1990) p-shell: Cohen-Kurath g A eff /g A =0.69 Detector for solar ν GT GT+IAS

p-sd shell: SFO Solar ν cross sections folded over 8 B ν spectrum Suzuki, Balantekin, Kajino, PR C 86, (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 = KB + monopole corrections ○ GXPF1 A = ・ Spin properties of fp-shell nuclei are well described B(GT - ) for 58 Ni Fujita et al. g A eff /g A free = MeV M1 strength (GXPF1J) g S eff /g S =0.75±0.2

● Electron-capture rate in steller environment

Sasano et al. PRL 107, (2011 ) f7/2 -> f5/2 f7/2 -> f7/2 f7/2 -> f5/2 e-capture rates in stellar environments ρY e =

Sasano et al. ● preliminary

58 Ni → 58 Co Exp: Hagemann et al., PL B579 (2004) 60 Ni → 60 Co 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 → 56 Ni (N=Z) → 56 Ni (e -, ν) 56 Co Y e =0.5 → Y e < 0.5 (neutron-rich) → production of neutron-rich isotopes; more 58 Ni Decrease of e-capture rate on 56 Ni → less production of 58 Ni. e-capture rates: GXPF1J < KB3G ←→ Y e (GXPF1J) > Y e (KB3G) Famiano

Problem of over-production of 58 Ni

Famiano

● Neutral current reaction on 56 Ni B(GT)=6.2 (GXPF1J) B(GT)=5.4 (KB3G) cf: HW02 gamma p n

Suzuki et al., PR C79 (2009) OBS: Cayrel et al., Astron. Astrophys. 416 (2004) Yoshida, Umeda, Nomoto Synthesis of Mn in Population III Star

R-Process Nucleosynthesis and Beta Decays of N=126 Isotones Focus on the 3 rd 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=g A eff /g A =0. 7 E x =0 ←→ g.s. of the parent nuclei GT strengths

g A eff /g A =0.7 E=0: g.s. of the parent nuclei SD+E1 (1 - ) strengths spin part only Q=g A eff /g A =0.7

Moller, Pfeiffer, Kratz, PR C 67, (2003) cf. Q=g A eff /g A =0.7, ε =2.0 (0 - ) Shell Model calculations Neumann-Cosel et al, PRL 82 (1999) Q=g s eff /g s =0.64: 2- in 90 Zr (e-scatt.)

r-process nucleosynthesis Constant Entropy Wind Model L ν =0.5x10 51 erg/s S=133 k B (γ, e -, e + ) dm/dt=2.34x10 -6 M sun τ= 5.60 ms for T 9 =5 ->T 9 =2 T 9f =0.8 Neutrino processes on n, p and 4 He are included Half-lives: Standard (Moller et al.) Modified

g A eff /g A =0.34, g V eff /g V = ΔQ =1.0 MeV Large quenchings are favored in A =206 (g A eff /g A,g V eff /g V )=(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 (g A eff /g A, g V eff /g V ） 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 ( 16 O) and new ν- 12 C, 13 C and ν- 16 O 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 56 Ni, 58 Ni and 60 Ni are well described by GXPF1J. Suzuki, Honma, Mao, Otsuka, Kajino, PR C83, (2011)

→ Abundance ratio of 58 Ni/ 56 Ni in type Ia supernova explosions is improved ・ New ν-nucleus reaction cross sections in 56 Ni → enhancement of production rates of Mn and Co in supernova explosions Suzuki, Honma et al., PR C79, (R) (2009) ・ Short half-lives for beta decays of N=126 isotones compared to a standard model (FRDM) → The 3 rd peak of the r-process element abundances is shifted toward larger mass number region. Suzuki, Yoshida, Kajino, Otsuka, PR C85, (2012)

Collaborators M. Honma a, T. Yoshida b, S. Chiba c, H. Mao d, K. Higashiyama e, T. Kajino b,f, T. Otsuka g B. Balantekin h, T. Umeda b, K. Nomoto b,i, Famiano f,j a University of Aizu b Department of Astronomy, University of Tokyo c Tokyo Institute of Technology d ENSPS, Strasbourg e Chiba Institute of Technology f National Astronomical Observatory of Japan g Department of Physics and CNS, University of Tokyo h University of Wisconsin i IPMU, j RIKEN