Rotational bands in the rare-earth proton emitters and neighboring nuclei
GT ( ) : Weak Process: Important roles in the Universe Combined Analysis of Mirror GT Transitions...
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Transcript of GT ( ) : Weak Process: Important roles in the Universe Combined Analysis of Mirror GT Transitions...
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