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 Ph. D Thesis of F. Molina (spokespersons, Y. Fujita, B. Rubio, W. Gelletly) B. RubioBrighton Jan 2011

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 2B. RubioBrighton Jan 2011

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

We choose Tz=-1 nuclei with Z=22 to 28 because these cases are specially “clean” since they involve only  f7/2 to f7/2 and  f7/2 to f5/ f 7/ p 3/2 1 f 5/2 2 p 1/2 1 f 7/2 2 p 3/2 1 f 5/2   and  2 p 1/2 First reason 4B. RubioBrighton Jan 2011

CE reactions T z =+1T z =-1T z = (p,n)-type For instance (3He,t) V    - decay   V  “in isospin symmetry space”, IAS This is the pattern we expect (  f 7/2 ) 2   f 7/2 f 5/2 (  f 7/2 ) 2   f 7/2 f 7/2 5B. RubioBrighton Jan 2011

CE reactions T z =+1T z =-1T z = (p,n)-type For instance (3He,t) V    - decay   V , IAS Second Reason We choose the Tz=-1  Tz=0 cases because 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 Decay Advantages : 6B. RubioBrighton Jan 2011

46 Ti 50 Cr 50 Fe 54 Ni 46 Cr ß+ ( 3 He,t) N=Z T z =0 T z = +1 T z = Fe 42 Ti Ca 22 We have the stable targets Tz=+1 We have large Q  -values Tz=-1 Adventages of studying f Shell Nuclei with T=1 Tz=(N-Z)/2 7B. RubioBrighton Jan 2011

(3He,t) CE RCNP(Osaka) 46 Ti 50 Cr 50 Fe 54 Ni 46 Cr ( 3 He,t) N=Z Zn Ni 54 Fe 42 Ti Ca 22 θ lab = 0° (3He,t) CE reaction 3He Stable Target triton 8B. RubioBrighton Jan 2011

9B. RubioBrighton Jan 2011

III. Beta Decay RISING Production of 54Ni,50Fe, 46Cr and 42Ti Beam MeV/u 10 9 pps Target Be 4g/cm2 Separation in flight with the Fragment Separator (FRS) 50Fe ~2 millions counts Typically 300 counts/sec Of the nucelus of interest 10B. RubioBrighton Jan 2011

15 Euroball Cluster Ge Detectors (7 crystals each) RISING (Ge Array) Francisco Molina IFIC(Valencia) Beta(keV) and H.I.(GeV) detector Santiago, December B. RubioBrighton Jan 2011

B. RubioBrighton Jan 2011

13 1+ B. RubioBrighton Jan 2011

Z.Hu et al. : Nucl. Instr. and Meth. In Phys. Res. A 419 (1998) y = p0+p1*x + p2*x 2 + p3*x 3 +p4*x 4 +p5*x 5, y=log(eff) and x=log(E) RISING Efficiency Simulation 14 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)

16 T1/2 analysis of 54Ni g.s nuclei was done using heavy ion implantation-beta correlations for identified 54Ni ions produced and implantaion beta-gamma correlations. Each decay was correlated with all implants happening before and after the decay To assure no-systematic errors and well defined background

17 T1/2 analysis of 54Ni g.s nuclei was done using heavy ion implantation-beta correlations for identified 54Ni ions produced and implantaion beta-gamma correlations. Each decay was correlated with all implants happening before and after the decay To assure no-systematic errors and well defined background

18 Least square fit

19 Experimental value of the ground state to ground state feeding estimation T 1/2 = T 1/2 = Systematic errors such as beta efficiency error or survival probability errors cancels!, only gamma efficiency counts!!! Experimental Result g.s. feed 54 Ni = Parent ?

20 Tz=-1 Tz=  , IAS This is a super-allowed 0+  0+ Fermi transition with B(F)=N-Z And hence ParentFermi estimExp. G.s feed 54Ni0.82(3)0.79(2) 50Fe0.74(4)0.74(2) 50Cr0.78(1)0.77(2) 42Ti0.49(1)0.44(4) Comparison of “g.s to g.s feeding” estimated from Fermi transition probability and our experimental result

21 Many 1+  0+, few 1+  2+, but never 1+  1+ M1 transitions were observed!!!!

22 Tz=-1 Tz=   IAS 2+ T=0 T=1 M1 transitions from T=0 to T=0 in self-conjugate nuclei are strongly suppressed!!!!

Results: B GT values from beta decay Isospin symmetry works in general (full strength) but some differences appear at high excitation energy, which should be understood This is the first experimental test of B GT symmetry in the f shell. These cases are specially “clean” since they involve only  f7/2 to f7/2 and  f7/2 to f5/2 kind of transitions and we compare only the two gs states 23B. RubioBrighton Jan 2011

summary 24 We 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 the Efficiency 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. RubioBrighton Jan 2011

25 FIN B. RubioBrighton Jan 2011

Results: B GT values from beta decay Isospin symmetry works in general (full strength) but some differences appear at high excitation energy, which should be understood This is the first experimental test of B GT symmetry in the f shell. These cases are specially “clean” since they involve only  f7/2 to f7/2 and  f7/2 to f5/2 kind of transitions and we compare only the two gs states 26B. RubioBrighton Jan 2011

27 Esta es la última tabla que me entregó Pancho sin errors en los valores de CE B. RubioBrighton Jan 2011

28B. RubioBrighton Jan 2011

N=Z Z=28 Z=20 N=28 N=20 Luckly enough we have all Stable targets in the f shell β+ or β- 29B. RubioBrighton Jan 2011

Absolute B GT normalisation is always needed: It can be obtained using the combined analysis Y. Fujita… et al. PRL 95 (2005) From  -decay B(F)=N-Z From (3He,t) We set up a series of experiments to test this idea 30B. RubioBrighton Jan 2011

31 T1/2 analysis of 54Ni g.s nuclei was done using heavy ion implantation-beta correlations for identified 54Ni ions produced and implantaion beta-gamma correlations. Each decay was correlated with all implants happening before and after the decay To assure no-systematic errors and well defined background Possible systematic errors a)Deadtime b)contaminants

32 Maximum likelihood fit

33 T1/2 from gammas 46Cr missing

34 Gamma spectrum after background subtraction from opposite pixel 46Cr missing

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Results: preliminary B GT values from beta decay Francisco Molina Analysis in progress IFIC(Valencia) A=54B(GT) decayB(GT) CE 937 keV0.471(55)0.493(62) 3378 keV0.074(14)0.079(11) 3889 keV0.064(17)0.103(14) 4544 keV0.075(27)0.147(20) A= keV0.547(90)0.510(14) 2404 keV0.126(23)0.151(40) 2685 keV0.090(19)0.106(28) 3380 keV0.281(55)0.350(93) A= keV0.330(329)0.368(44) 1433 keV0.107(107)0.122(15) 2462 keV0.146(146)0.201(24) 2698 keV0.111(111)0.205(25) 2978 keV0.479(478)0.625(75) 3870 keV0.105(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 test of B GT symmetry in the f shell. These cases are specially “clean” since they involve only  f7/2 to f7/2 and  f7/2 to f5/2 kind of transitions and we compare only the two gs states 37B. RubioBrighton Jan 2011

Beta Decay Results and comparison with CE A=54, T=1 First 4th GT States till 4.5MeV were seen by beta decay 937 (1+) 3377 (1+) 3895 (1+) 4550 (1+) 4828 (1+) 5921 (1+) 4550 (1+) counts counts counts 150 counts 1816 counts 2598 counts 38B. RubioBrighton Jan 2011

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+) 2694 (1+) 2411 (1+) 652 (1+) 3654 (1+) 4332 (1+) 5728 (1+) B. RubioBrighton Jan 2011

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, (2006) B. RubioBrighton Jan 2011

Z.Hu et al. : Nucl. Instr. and Meth. In Phys. Res. A 419 (1998) y = p0+p1*x + p2*x 2 + p3*x 3 +p4*x 4 +p5*x 5, y=log(eff) and x=log(E) Rising Ge simulation Including + Si + Box 2.26% RISING Efficiency Simulation 41

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B. RubioBrighton Jan 2011

1+ 45B. RubioBrighton Jan 2011