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GT () : Important weak process
decay : absolute B(GT), limited to low-lying stateCE reactions : relative B(GT), highly Ex region
decay isospin symmetry CE reaction
High-resolution (3He,t) CE reaction
and analogous -decay for the study of GT strengths
Yoshitaka FUJITA (Osaka Univ.) @ Spin 2006 / Oct. 02, 2006
mainly by
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
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) spectra
Y. Fujita et al.,EPJ A 13 (’02) 411.
H. Fujita et al.,Dr. Th. & PRC
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
High resolution 54Fe(3He,t) spectrumT. Adachi et al.
Target nuclei under study : T0=1 46Ti, 50Cr, 54Fe, 58NiT0=2 48Ti, 52Cr, 56Fe, 60NiT0=3 50Ti, 62NiT0=4 64Ni
26MgZ=12, N=14
26AlZ=13, N=13
26SiZ=14, N=12
Tz=+1/2(Z,N+1) (Z+1,N)
-decay
Tz=-1/2
VV
(p,n)-typeV
M1(e,e')
-decayM1
-decayM1
23NaZ=11, N=12
23MgZ=12, N=11
T=1 symmetry
Connection between Charge Exchange & decay
T=1/2 symmetry 0+ 1+
26MgZ=12, N=14
26AlZ=13, N=13
26SiZ=14, N=12
Tz=+1/2(Z,N+1) (Z+1,N)
-decay
Tz=-1/2
VV
(p,n)-typeV
M1(e,e')
-decayM1
-decayM1
23NaZ=11, N=12
23MgZ=12, N=11
T=1 symmetry
Connection between Charge Exchange & decay
T=1/2 symmetry 0+ 1+
not enough-decay
data
not forTi, Cr, Fe
region
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
by 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)
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 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
by B. Rubio
Mirror nuclei
48V
52Mn
56Co50Co
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
B. Rubio, Y. Fujita
Mirror nuclei
48V
52Mn
56Co50Co
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
B. Rubio, Y. Fujita
Even T1/2’s are uncertain!
-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(total proton counts: ~160)
itFeedings /1
abs. B(GT) distributionfrom 52Cr(3He,t)
QEC=11.262 MeV
B(F)=N-ZIsospin symmetry estimation
T1/2= 56 (10) ms
SM cal. (PRC 57, 2316, ’98)
T1/2= 50 msMass formula (T. Tachibana et al.)
T1/2= 35 ms