Yoshitaka FUJITA (Osaka Univ.) Hirschegg Workshop /2006, Jan GT (  ) : Important weak response GT transitions of Astrophysics Interest

Supernova Cycle

mainly by  &  K.L &G.M-P Rev.Mod.Phys.75(’04)819 (A,Z)=nuclei in the Fe, Ni region Crucial Weak Processes during the Collapse

SM-cal: GT- from Ni isotopes E. Caurier et al., NPA653 (‘99) 439 KB3G int. (p,n) exp. SM cal.

Yoshitaka FUJITA (Osaka Univ.) Hirschegg Workshop /2006, January GT (  ) : Important weak response  decay : absolute B(GT), limited to low-lying state CE reaction : relative B(GT), highly Ex region  decay  isospin symmetry  CE reaction GT transitions of Astrophysics Interest

Direct Reactions with Light Projectiles Projectile 3 He Target Coulomb Excitation Elastic Scattering Inelastic Scattering Pick-up Stripping Charge-exchange Similarity with  decay! by Berta Rubio |i>  |f> interaction (operator) Ejectile t

**( 3 He,t): high resolution and sensitivity !

9 Be( 3 He,t) 9 B spectrum (at various scales)

9 Be( 3 He,t) 9 B spectrum (II) Isospin selection rule prohibits proton decay of T=3/2 state!

Key Words High Resolution In Charge Exchange Reactions --at Intermediate Incident Energies-- ( 3 He,t) reaction : one order better resolution than in a (p,n) reaction Comparison with  decay Similarity of Active Operators Gamow-Teller operator in  decay (weak interaction) Spin-isospin interaction in reactions (strong interaction) Isospin Symmetry of Nuclear Structure Isospin-Symmetry GT Transitions are expected

**B(GT) derivation in Charge Exchange Reactions Interaction & Reaction Mechanism

B(GT) derivation

Nucleon-Nucleon Int. : E in dependence at q =0 V  VV VV VV central-type interactions Simple one-step reaction mechanism at intermediate energies!

N.-N. Int. :  & Tensor-  q-dependence  TT largest at q=0 ! larger than others ! Love & Franey PRC 24 (’81) 1073

B(GT) derivation

Resolutions Now and Then Y. Fujita et al., EPJ A 13 (’02) 411. H. Fujita et al., Dr. Th. & PRC

**Isospin Symmetry Structure in a Mass A Isobar System

T=1 system 50 Cr A=50 system Coulomb Energy: important 50 Mn 50 Fe

T=1 symmetry : Structures & Transitions 50 Mn Z=25, N=25 50 Fe Z=26, N=24 50 Cr Z=24, N=26

**High Resolution Experiment

Grand Raiden Spectrometer Large Angle Spectrometer

RCNP Ring Cyclotron

Beam line WS-course T. Wakasa et al., NIM A482 (’02) 79. Grand-Raiden Spectrometer RCNP Ring Cyclotron High-dispersive WS-course

Matching Techniques

**GT Transitions in fp--shell Nuclei -important in supernova explosion-

Onion Structure in a Red Giant

mainly by  &  can be studied by ( 3 He,t) K.L &G.M-P Rev.Mod.Phys.75(’04)819 (A,Z)=nuclei in the Co, Fe, Ni region Crucial Weak Processes during the Collapse

(p, n) spectra for Fe and Ni Isotopes Rapaport & Sugarbaker Rev. Mod. Phys. (’94)

54 Fe(p,n) & 54 Fe( 3 He,t) B.D. Anderson et al., (p, n) at IUCF

( 3 He,t) spectra: T=1, pf-shell nuclei (I) T. Adachi et al. PRC, in press

( 3 He,t) spectra: T=1, pf-shell nuclei (II)

26 Mg Z=12, N=14 26 Al Z=13, N=13 26 Si Z=14, N=12 23 Na Z=11, N=12 23 Mg Z=12, N=11 T=1 symmetry Connection between Charge Exchange &  decay T=1/2 symmetry 0 +  1 +

**Derivation of “absolute” B(GT) values - for A=50 system-

50 Cr( 3 He,t) 50 Mn

Isospin Symmetry Transitions: 50 Cr( 3 He,t)  50 Mn   -decay 50 Fe Q EC =8.152(61) MeV T 1/2 =0.155(11) s (Z,N)=(24,26)(25,25)(26,24)

50 Fe  -decay measurement 50 Fe S p =4.59  + decay 0 + Q EC =8.152(61) MeV T 1/2 =0.155(11) s No feeding ratios!

50 Cr( 3 He,t)  50 Mn   -decay 50 Fe B(GT)=0.60(14) Q EC =8.152(61) MeV T 1/2 =0.155(11) s *assuming no brancing to higher excited states!

**Reconstruction of  decay from ( 3 He,t) - assuming isospin symmetry -

Simulation of  -decay spectrum  -decay feeding ratio is expected !

Absolute B(GT) values -via reconstruction of  -decay spectrum-  -decay experiment T 1/2 =0.155(11) s New value B(GT)=0.50(13) *20% smaller than the  -decay: 0.60(16) Absolute intensity: B(GT) Y. Fujita et al. PRL 95 (2005) B(F)=N-Z Relative feeding intensity from ( 3 He,t) t i =partial half-life

Important messages *The largest uncertainty comes from the error of T 1/2 measurement in the  -decay *Other error sources Q-value of the  -decay Uncertainties of peak yields  Accurate T 1/2 measurement is important ! **Measurement of T 1/2 -value is easier ! (Measurement of branching ratio is more difficult)

Study of Mirror GT Transitions for T=1 System 54 Fe Z=26, N=28 54 Co Z=27, N=27 54 Ni Z=28, N=26 Leuven Valencia Surrey Osaka

Summary Words High Resolution ( 3 He,t) reaction : one order better resolution than in a (p,n) reaction  good tool to study B(GT) distribution (relative values) Isospin Symmetry Combined Analysis based on Isospin Symmetry ( 3 He,t) IV-spin interaction in reactions (strong interaction) Gamow-Teller operator in  decay (weak interaction)  A New Step toward the accurate determination of B(GT) (absolute values)

High resolution 54 Fe( 3 He,t) spectrum T. Adachi et al. Target nuclei under study : T 0 =1 46 Ti, 50 Cr, 54 Fe, 58 Ni T 0 =2 48 Ti, 52 Cr, 56 Fe, 60 Ni T 0 =3 50 Ti, 62 Ni T 0 =4 64 Ni

**Thank you for your attention !