GT () : Weak Process: Important roles in the Universe

Combined Analysis of Mirror GT Transitions for the study of Proton-

Rich Far-Stability Nuclei

Yoshitaka FUJITA (Osaka Univ.) 　　　　　　 INPC 2007 / June 3-8

operator : simple operator (states with different shapes are not connected)

Direct Reactions with Light Projectiles

Projectile3He

Target

Coulomb Excitation

Elastic Scattering

Inelastic Scattering

Pick-up Stripping

Charge-exchange

Similarity with decay!by Berta Rubio

|i> |f>

-int.

Ejectile t

B(GT) derivation

GT () : Weak Process: Important roles in the Universe

decay : Absolute B(GT), limited to low-lying stateCE reactions : relative B(GT), Highly Excitation Region

decay isospin symmetry CE reaction

Combined Analysis of Mirror GT Transitions for the study of Proton-

Rich Far-Stability Nuclei

Yoshitaka FUJITA (Osaka Univ.) 　　　　　　 INPC 2007 / June 3-8

operator : simple operator (states with different shapes are not connected)

Key Words

•High Energy Resolution in the Experiment

•Isospin Symmetry in the Nuclear Structure

•Combined Analysis of -decay and CE Reaction

58Ni(p, n)58Cu Ep = 160 MeV

58Ni(3He, t)58Cu E = 140 MeV/u

Cou

nts

Excitation Energy (MeV)0 2 4 6 8 10 12 14

Comparison of (p, n) and (3He,t) ０ o spectra

Y. Fujita et al.,EPJ A 13 (’02) 411.

H. Fujita et al.,PRC 75 (’07) 034310

Sp

J. Rapaport et al.NPA (‘83)

T> states

GTGR

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

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

9Be(3He,t)9B spectrum (II)

Isospin selection rule prohibits proton decay of T=3/2 state!

Isospin Selection Rule : in p-decay of 9B

+

9B*p + 8Be*

1p-1h

p n p nTz : -1/2 + 0 = -1/2T : 1/2 + 0 (low lying) = 1/2

T : 1/2 + 1 (higher Ex) = 1/2 & 3/2*T=1 state in 8Be is

only above Ex=16.6 MeV

9Be(3He,t)9B spectrum (III)

14.655 MeV T=3/2 state is very weak!Strength ratio of T=1/2 vs. 3/2, 3/2- states: 140:1

α

Shell Structure and Cluster Structure

αn

α

αp

9Be 9B

9Li 9C

T=3/2

Tz=3/2

Tz=1/2 Tz=-1/2

Tz=-3/2

Excited state: SM-like

g.s.: Cluster-like

suggestion byY. Kanada-En’yo

proton: p3/2 closedneutron: p3/2 closed

RCNP Ring Cyclotron

Good quality 3He beam (140 MeV/nucleon)

Grand Raiden Spectrometer

Large AngleSpectrometer

3He beam

(3He, t) reaction

Matching Techniques

Lateral dispersion matching

E ～ 35 keV Horiz. angle resolution sc > 15mrad

Achromatic beamtransportation

E ～200 keV for 140MeV/u 3He beam

Angular dispersionmatching

sc ～ 5mrad

Focal plane

Magnetic Spectrometer

Target

Y. Fujita et al., N.I.M. B 126 (1997) 274.

a) b) c)

-Δ p +Δ p0

H. Fujita et al., N.I.M. A 484 (2002) 17.

-Δ p 0 +Δ p

**Isospin Symmetry Structurein Mass A Nuclei (Isobars)

Nuclei & Coin

Coin

back front

Nuclei

isospin T=1 triplet

5024Cr26

Tz= 1 Tz= -1

5026Fe24

Tz= 0

5025Mn25

T=1 system

5024Cr26

A=50 systemCoulomb Energy: important

5025Mn25

5026Fe24

T=1 symmetry : Structures & Transitions

5024Cr26

5025Mn25

5026Fe24

B(GT) values from Symmetry Transitions (A=26)

Y. Fujita et al., PRC 67 (‘03) 064312

Supernova Cycle

important

K.L &G.M-PRev.Mod.Phys.75(’04)819

(A,Z)=nuclei in theCr, Mn, Fe, Co, Ni region pf -shell Nuclei !

Crucial Weak Processesduring the

Core Collapse

GT statesin

A=42-58Tz=0 nuclei

starting fromTz= +1

pf –shell nuclei

GT strengths in A=42-58

Log ft =3.2 [B(GT)=2.4]

GT strengths in A=42-58

GT-GR

GT statesin

A=42-58Tz=0 nuclei

T. Adachi et al.

H. Fujita et al.

Y. Fujita et al.

**Derivation of “absolute” B(GT) values

-decay: T1/2 and absolute B(GT) values but only for the low-lying states

*(3He,t) reaction: highly-excited states can be accessed but only the relative B(GT) values

Mirror nuclei

46Ti

50Cr

54Fe50Fe

54Ni

46Cr

ß+

(3He,t)

N=Z

T=1 Isospin Symmetry in pf-shell Nuclei

5428Ni26

5426Fe28

T z=0

T z=1

T z=-1

LeuvenValencia

SurreyOsaka

B. Rubio

Isospin Symmetry Transitions: 50Cr(3He,t) 50Mn -decay 50Fe

QEC=8.152(61) MeVT1/2=0.155(11) s

0.651

(Z,N)= (24,26) (25,25) (26,24)

50Cr(3He,t)50Mn

**Reconstruction of decay from (3He,t)

---assuming isospin symmetry ---

Simulation of -decay spectrum

-decay feeding ratios are deduced !

Y. Fujita et al.PRL 95 (2005)

Absolute B(GT) values-via reconstruction of -decay spectrum-

GTi

iFermi ttT111

2/1

-decay experiment

T1/2=0.155(11) s

itFeedings /1

New value B(GT)=0.50(13) *20% smaller than deduced in the -decay: 0.60(16)

Absolute intensity: B(GT)

Y. Fujita et al.PRL 95 (2005)

B(F)=N-Z Relative feeding intensity from (3He,t)

ti =partial half-life

Mirror nuclei

46Ti

50Cr

54Fe50Fe

54Ni

46Cr

ß+

(3He,t)

N=Z

T=1 Isospin Symmetry in pf-shell Nuclei

5428Ni26

5426Fe28

T z=0

T z=1

T z=-1

LeuvenValencia

SurreyOsaka

B. Rubio

Mirror nuclei

48V

52Mn

56Co52Co

56Cu

48Mn+

(3He,t)

N=Z

T = 2 Isospin Symmetry in pf-shell Nuclei

5228Ni24

5224Cr28

T z=0

T z=1

T z=-1

52Ni

T z=2

T z=-2

52Cr48Cr

52Fe

56Ni

56Fe

56Zn

48Ti

48Fe

by Y. Fujita, B. Rubio

Mirror nuclei

48V

52Mn

56Co52Co

56Cu

48Mn+

(3He,t)

N=Z

T = 2 Isospin Symmetry in pf-shell Nuclei

5228Ni24

5224Cr28

T z=0

T z=1

T z=-1

52Ni

T z=2

T z=-2

52Cr48Cr

52Fe

56Ni

56Fe

56Zn

48Ti

48Fe

by Y. Fujita, B. Rubio

How is the T1/2 value?

Comparison: (p, n) and (3He,t)IAS

g.s.

52Cr(p, n)52MnEp =120 MeV

D. Wang et al., NP A480 (’88) 285

-decay Half-life T1/2

-via reconstruction of -decay spectrum-

GTi

iFermi ttT111

2/1

itFeedings /1

abs. B(GT) distributionfrom (3He,t)

B(F)=N-Z

52Ni -decay Half-life T1/2

GTi

iFermi ttT111

2/1

-decay exp. (PRC 49, 2440, ‘94)

T1/2= 38 (5) ms [40.8(2) ms (’06 GANIL)]

itFeedings /1

abs. B(GT) distribution[52Cr(3He,t)]

QEC=11.88 MeV[-decay + IMME (‘06)]

B(F)=N-ZIsospin symmetry estimation

T1/2= 39 (3) ms

SM cal. (PRC 57, 2316, ’98)

T1/2= 50 msMass formula (T. Tachibana et al.)

T1/2= 35 ms

Uncertainty of the Q-value should still be considered !

Analog Relationship (T=0,1,2)

stable

58Ni(p, n)58Cu Ep = 160 MeV

58Ni(3He, t)58Cu E = 140 MeV/u

Cou

nts

Excitation Energy (MeV)0 2 4 6 8 10 12 14

Comparison of (p, n) and (3He,t) ０ o spectra

Y. Fujita et al.,EPJ A 13 (’02) 411.

H. Fujita et al.,PRC 75 (’07) 034310

Sp

J. Rapaport et al.NPA (‘83)

T=2

Analog Relationship (T=0,1,2)

stable

Summary* Isospin Symmetry was introduced* High resolution of the (3He,t) reaction

allowed the comparison of analogous transitions * Properties of proton-rich “far-stability nuclei” is deduced by the combined analysis of -decay and (3He,t) reaction

--- B(GT), Half-life T1/2 --- **Accurate measurements of T1/2 & Mass are very important**

Collaboration of Stable beam facility

and RI beam facility is very important!

High-Resolution CollaborationsGent (Belgium) : (3He, t), (d, 2He), (’)GSI, Darmstadt (Germany) : inverse kinematics ISOLDE, CERN (Switzerland) : decayiThemba LABS. (South Africa) : (p, p’), (3He, t)Jyvaskyla (Finland) : decayKoeln (Germany) : decay, (3He, t), theoryKVI, Groningen (The Netherlands) : (d, 2He)Leuven (Bergium) : decayLTH, Lund (Sweden) : theoryOsaka University (Japan) : (p, p’), (3He, t), theorySurrey (GB) : decayTU Darmstadt (Germany) : (e, e’), (3He, t)Valencia (Spain) : decayMichigan State University (USA) : theory, (t, 3He)Muenster (Germany) : (d, 2He), (3He,t)University of Tokyo : theory