1 Isospin symmetry. Beta-decay studie of Tz=-1 nuclei at Rising. B. Rubio for the Valencia-Osaka-Surrey-Leuven-Santiago Istambul-Lund-Legnaro Collaboration Ph. D Thesis of F. Molina (spokespersons, Y. Fujita, B. Rubio, W. G B. Rubio Brighton 12-13 Jan 2011
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1 Isospin symmetry. Beta-decay studies of Tz=-1 nuclei at Rising. B. Rubio for the Valencia-Osaka-Surrey-Leuven-Santiago-GSI Istambul-Lund-Legnaro Collaboration.
N=Z Z=28 Z=20 N=28 N=20 In this work I will present the study Of the beta-decay of the Tz=-1 nuclei 54Ni, 50Fe,46Cr and 42Ti Fragmentation of 58Ni 3B. RubioBrighton Jan 2011
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Brighton 12-13 Jan 2011 1
Isospin symmetry. Beta-decay studies of Tz=-1 nuclei at Rising.
Ph. D Thesis of F. Molina(spokespersons, Y. Fujita, B. Rubio, W. Gelletly)
B. Rubio
Brighton 12-13 Jan 2011 2
B(GT) kI (E)
f (Q E,Z)T1/ 2
I (E)
B(GT) f k k
k i
2
T1/ 2
In this paper we are interested in extracting information about the B(GT) strength in f-shell nuclei from beta decay studies
Theoretically
Experimentally
From the present experiment
Parent half life
Beta feeding to states in the daughter nucleus
B. Rubio
Brighton 12-13 Jan 2011 3
N=Z
Z=28
Z=20
N=28
N=20
In this work I will present the studyOf the beta-decay of the Tz=-1 nuclei54Ni, 50Fe,46Cr and 42Ti
Fragmentation of 58Ni
B. Rubio
Brighton 12-13 Jan 2011 4
We choose Tz=-1 nuclei with Z=22 to 28 because these cases are specially “clean” since they involve only
f7/2 to f7/2and
f7/2 to f5/2
281 f 7/2
282 p 3/21 f 5/22 p 1/2
1 f 7/2
2 p 3/21 f 5/2
and
2 p 1/2
First reason
B. Rubio
Brighton 12-13 Jan 2011 5
CE reactions
Tz=+1 Tz=-1Tz=0
0+ 0+0+
1+1+
1+
1+
(p,n)-typeFor instance(3He,t)
V
+-decay
V
“in isospin symmetry space”
, IAS
This is the pattern we expect
(f7/2)2 f7/2 f5/2
(f7/2)2 f7/2 f7/2
(f7/2)2 f7/2 f7/2B. Rubio
Brighton 12-13 Jan 2011 6
CE reactions
Tz=+1 Tz=-1Tz=0
0+ 0+0+
1+1+
1+
1+
(p,n)-typeFor instance(3He,t)
V
+-decay
V
, IAS
Second Reason
We choose the Tz=-1 Tz=0 casesbecause the mirror Tz=+1 Tz=0 cases exists
CE reactions: No restriction in excitation energy of Gamow-Teller states
Beta Decay: Absolute Normalization of B(GT)
If isospin symmetry exists, mirror nuclei should populate the same states with the same probability, in the daughter nuclei, in the two mirror processes: CE reactions and Beta DecayAdvantages :
B. Rubio
Brighton 12-13 Jan 2011 7
46Ti
50Cr
50Fe
54Ni
46Cr
ß+(3He,t)
N=Z
T z=0
T z= +1
T z= -1
54Fe
42Ti
4220Ca22
We have the stable targetsTz=+1
We have large Q-valuesTz=-1
Adventages of studying f Shell Nuclei with T=1
Tz=(N-Z)/2B. Rubio
Brighton 12-13 Jan 2011 8
(3He,t) CE Reactions @ RCNP(Osaka)
46Ti
50Cr
50Fe
54Ni
46Cr
(3He,t)
N=Z
5830Zn28
58Ni
54Fe
42Ti
4220Ca22
θlab = 0° (3He,t) CE reaction
3He
3He
Stable Target
triton
B. Rubio
Brighton 12-13 Jan 2011 9B. Rubio
Brighton 12-13 Jan 2011 10
III. Beta Decay Experiments @ RISINGProduction of 54Ni,50Fe, 46Cr and 42TiBeam 58Ni@680 MeV/u 109 ppsTarget Be 4g/cm2
Separation in flight with theFragment Separator (FRS)
50Fe
~2 millions countsTypically 300 counts/secOf the nucelus of interest
B. Rubio
Brighton 12-13 Jan 2011 11
15 Euroball Cluster Ge Detectors (7 crystals each)RISING (Ge Array)
Francisco Molina IFIC(Valencia)
Beta(keV) and H.I.(GeV) detector
Santiago, December 2009B. Rubio
Brighton 12-13 Jan 2011 12
3395
1+
3895
1+
4550
1+
4828
1+
3395
1+
3895
1+
4550
1+
4828
1+
1+
1+
1+
1+
B. Rubio
Brighton 12-13 Jan 2011 13
1+ 1+
1+
1+
B. Rubio
14Z.Hu et al. : Nucl. Instr. and Meth. In Phys. Res. A 419 (1998) 121-131
y = p0+p1*x + p2*x2 + p3*x3 +p4*x4+p5*x5 , y=log(eff) and x=log(E)
RISING Efficiency Simulation
Rising Ge simulation Including + Si + Box
15
Combined Analysis (CE – β Decay)
j
A precise value of the parent half-life is very important!!!
In β decay
In charge exchange
Fujita et al PRL 95 (2005) 212501
16
T1/2 analysis of 54Ni g.s nuclei was done using heavy ion implantation-beta correlationsfor identified 54Ni ions produced and implantaion beta-gamma correlations .
Each decay was correlated with all implants happening before and after the decayTo assure no-systematic errors and well defined background
17
T1/2 analysis of 54Ni g.s nuclei was done using heavy ion implantation-beta correlationsfor identified 54Ni ions produced and implantaion beta-gamma correlations .
Each decay was correlated with all implants happening before and after the decayTo assure no-systematic errors and well defined background
HI-beta correlations same pixel
HI-beta correlations opposite pixel
Background normalised
18
Least square fit
19
Experimental value of the ground state to ground state feeding estimation
T1/2 =114.71.7T1/2 =114.20.3
Systematic errors such as beta efficiency error or survival probability errorscancels!, only gamma efficiency counts!!!
Experimental Result g.s. feed 54Ni =0.792
Parent
?
20
Tz=-1
Tz=0
0+
0+
1+1+
1+
1+
, IAS
This is a super-allowed 0+0+ Fermi transition with B(F)=N-ZAnd hence
Comparison of “g.s to g.s feeding”estimated from Fermi transition probabilityand our experimental result
21
Many 1+ 0+ , few 1+ 2+, but never 1+ 1+ M1 transitions were observed!!!!
22
Tz=-1
Tz=0
0+
0+
1+1+
1+
1+
IAS
2+T=0
T=0
T=0
T=0
T=1
T=1
M1 transitions from T=0 to T=0 in self-conjugate nuclei are strongly suppressed!!!!al
lpw
ed
Strongly supressed
Brighton 12-13 Jan 2011 23
Results: BGT values from beta decayIsospin symmetry works in general (full strength) but some differences appear at high excitation energy, which should be understood
This is the first experimental testof BGT symmetry in the f shell. These cases are specially “clean” since they
involve only
f7/2 to f7/2and
f7/2 to f5/2
kind of transitionsand we compare only the two gs states
B. Rubio
Brighton 12-13 Jan 2011 24
summaryWe have studied the beta decay of four Tz=-1 nuclei in the f7/2 shell
They were all produce in fragmentation of 58Ni beams
In spite of the complex set-up we could get extremely clean results
Very accurate T1/2 and g.s beta decay feeding values were obtained
The four decay schemes were obtained and the corresponding B(GT)values for all observed levels could be determined where only Q-beta
A very selective isospin Quasi selection rule of was clearly observed
The results were compared with the mirror CE reaction process thanks to theEfficiency and high quality of the RISING array. The isospin symmetry works well for the strong transitions but small transitions show difference up to 50% which still have to be understood.
ONE CAN PERFORME DELICATE SPECTROSCOPY STUDIES IN FRAGMENTATION REACTIONS IF ONE ACHIEVES CLEAN IMPLANTATION
B. Rubio
Brighton 12-13 Jan 2011 25
FIN
B. Rubio
Brighton 12-13 Jan 2011 26
Results: BGT values from beta decayIsospin symmetry works in general (full strength) but some differences appear at high excitation energy, which should be understood
This is the first experimental testof BGT symmetry in the f shell. These cases are specially “clean” since they
involve only
f7/2 to f7/2and
f7/2 to f5/2
kind of transitionsand we compare only the two gs states
B. Rubio
Brighton 12-13 Jan 2011 27
Esta es la última tabla que me entregó Pancho sin errors en los valores de CE
B. Rubio
Brighton 12-13 Jan 2011 28B. Rubio
Brighton 12-13 Jan 2011 29
N=Z
Z=28
Z=20
N=28
N=20
Luckly enough we have all Stable targets in the f shell
β+ or β-
B. Rubio
Brighton 12-13 Jan 2011 30
Absolute BGT normalisation is always needed:It can be obtained using the combined analysis
Y. Fujita… et al.PRL 95 (2005)
+GTi
iFermi ttT111
2/1
From-decay B(F)=N-Z From (3He,t)
We set up a series of experiments to test this idea
B. Rubio
31
T1/2 analysis of 54Ni g.s nuclei was done using heavy ion implantation-beta correlationsfor identified 54Ni ions produced and implantaion beta-gamma correlations .
Each decay was correlated with all implants happening before and after the decayTo assure no-systematic errors and well defined background
HI-beta correlations same pixel
HI-beta correlations opposite pixel
Possible systematic errorsa) Deadtimeb) contaminants
32
Maximum likelihood fit
33
T1/2 from gammas
46Cr missing
34
Gamma spectrum after background subtraction from opposite pixel
46Cr missing
35
36
Brighton 12-13 Jan 2011 37
Results: preliminary BGT values from beta decay
Francisco MolinaAnalysis in progress IFIC(Valencia)
A=54 B(GT) decay B(GT) CE
937 keV 0.471(55) 0.493(62)
3378 keV 0.074(14) 0.079(11)
3889 keV 0.064(17) 0.103(14)
4544 keV 0.075(27) 0.147(20)
A=50
652 keV 0.547(90) 0.510(14)
2404 keV 0.126(23) 0.151(40)
2685 keV 0.090(19) 0.106(28)
3380 keV 0.281(55) 0.350(93)
A=46
994 keV 0.330(329) 0.368(44)
1433 keV 0.107(107) 0.122(15)
2462 keV 0.146(146) 0.201(24)
2698 keV 0.111(111) 0.205(25)
2978 keV 0.479(478) 0.625(75)
3870 keV 0.105(119) 0.117(14)
Large B(GT) uncertainties are due to the errors in the beta decay half-life. A better value should come from the present experiment.
Isospin symmetry works in general (full strength) but some differences appear at high excitation energy, which should be understood
This is the first experimental testof BGT symmetry in the f shell. These cases are specially “clean” since they
involve only
f7/2 to f7/2and
f7/2 to f5/2
kind of transitionsand we compare only the two gs states
B. Rubio
Brighton 12-13 Jan 2011 38
Beta Decay Results and comparison with CEA=54, T=1
First 4th GT States till 4.5MeV were seen by beta decay
937
(1+)
937
(1+)
3377
(1+)
3377
(1+)
3895
(1+)
3895
(1+)
4550
(1+)
4828
(1+)
5921
(1+)
4550
(1+)0+
1
+0+
1
+9402 counts
94448 counts
0+
1+
0+
1+
0+
1+0+
1
+
347 counts
150 counts
1816 counts
2598 counts
B. Rubio
Brighton 12-13 Jan 2011 39
A=50, T=1
First 4th GT States till 3.3 MeV were seen by beta decay
652
(1+)
2411
(1+)
2694
(1+)
3392
(1+)
3392
(1+)
2694
(1+)
2411
(1+)
652
(1+)
3654
(1+)
4332
(1+)
5728
(1+)
0+
1+
0+
1+
0+
1+
0+
1+
0+
1+
0+
1+
0+
1+
0+
1+
0+
1+
0+
1+
B. Rubio
Brighton 12-13 Jan 2011 40
A=46, T=1
All the GT States were seen by beta decay
994
(1+)
1433
(1+)
2461
(1+)
2699
(1+)
2978
(1+)
3870
(1+)
994
(1+)
1432
(1+)
2460
(1+)
2697
(1+)
2978
(1+)
3870
(1+)
T. Adachi et al., PRC 73, 024311 (2006).
0+
1+
0+
1+
0+
1+
0+
1+
0+
1+
0+
1+
0+
1+
0+
1+
0+
1+
0+
1+
0+
1+
0+
1+
B. Rubio
41Z.Hu et al. : Nucl. Instr. and Meth. In Phys. Res. A 419 (1998) 121-131
y = p0+p1*x + p2*x2 + p3*x3 +p4*x4+p5*x5 , y=log(eff) and x=log(E)