Isospin symmetry Betadecay studies of Tz1 nuclei at

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. Rubio Brighton 12 -13 Jan 2011 1

In this paper we are interested in extracting information about the B(GT) strength in f-shell nuclei from beta decay studies Theoretically Experimentally Parent half life From the present experiment B. Rubio Beta feeding to states in the daughter nucleus Brighton 12 -13 Jan 2011 2

N= Z In this work I will present the study Of the beta-decay of the Tz=-1 nuclei 54 Ni, 50 Fe, 46 Cr and 42 Ti Fragmentation of 58 Ni Z=28 Z=20 N=28 B. Rubio N=20 Brighton 12 -13 Jan 2011 3

First reason We choose Tz=-1 nuclei with Z=22 to 28 because these cases are specially “clean” since they involve only f 7/2 to f 7/2 and f 7/2 to f 5/2 28 2 p 1/2 1 f 5/2 2 p 3/2 28 1 f 7/2 2 p 1/2 1 f 5/2 2 p 3/2 1 f 7/2 and B. Rubio Brighton 12 -13 Jan 2011 4

This is the pattern we expect “in isospin symmetry space” CE reactions 1+ 1+ 1+ + -decay (p, n)-type For instance (3 He, t) Vst 1+ st 0+ Tz=+1 B. Rubio , IAS Vt 0+ Tz=0 t 0+ ( f 7/2)2 f 7/2 f 5/2 ( f 7/2)2 f 7/2 Tz=-1 Brighton 12 -13 Jan 2011 5

Second Reason We choose the Tz=-1 Tz=0 cases because the mirror Tz=+1 Tz=0 cases exists 1+ 1+ 1+ CE reactions (p, n)-type For instance (3 He, t) Vst 0+ Tz=+1 B. Rubio + -decay st 1+ , IAS Vt 0+ Tz=0 t 0+ Tz=-1 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 : CE reactions: No restriction in excitation energy of Gamow-Teller states Beta Decay: Absolute Normalization Brighton 12 -13 Jan 2011 6 of B(GT)

Adventages of studying f Shell Nuclei with T=1 We have large Q -values Tz=-1 Z = N 54 Ni 50 Fe 54 Fe 46 Cr 42 Ti ß+ 1 = Tz=(N-Z)/2 B. Rubio 46 Ti (3 He, t) Tz 0 = Tz 50 Cr 1 + = Tz 42 We have the stable targets Tz=+1 20 Ca 22 Brighton 12 -13 Jan 2011 7

(3 He, t) CE Reactions @ RCNP(Osaka) θlab = 0° (3 He, t) CE reaction Stable Target 3 He 58 Zn 30 28 54 Ni 50 Fe 58 Ni 46 Cr 54 Fe 42 Ti 50 Cr triton 46 Ti Z N= 3 He (3 He, t) 42 Ca 20 22 B. Rubio Brighton 12 -13 Jan 2011 8

B. Rubio Brighton 12 -13 Jan 2011 9

III. Beta Decay Experiments @ RISING Production of 54 Ni, 50 Fe, 46 Cr and 42 Ti Beam 58 Ni@680 Me. V/u 109 pps Target Be 4 g/cm 2 Separation in flight with the Fragment Separator (FRS) 50 Fe ~2 millions counts Typically 300 counts/sec Of the nucelus of interest B. Rubio Brighton 12 -13 Jan 2011 10

RISING (Ge Array) 15 Euroball Cluster Ge Detectors (7 crystals each) Beta(ke. V) and H. I. (Ge. V) detector B. Rubio Francisco Molina IFIC(Valencia) Brighton 12 -13 Jan 2011 11 Santiago, December 2009

1+ 1+ 1+ B. Rubio Brighton 12 -13 Jan 2011 1+ 12 4828 1+ 4550 1+ 4828 1+ 3895 1+ 3395 1+

1+ 1+ B. Rubio Brighton 12 -13 Jan 2011 13

RISING Efficiency Simulation Rising Ge simulation Including + Si + Box y = p 0+p 1*x + p 2*x 2 + p 3*x 3 +p 4*x 4+p 5*x 5 , y=log(eff) and x=log(E) Z. Hu et al. : Nucl. Instr. and Meth. In Phys. Res. A 419 (1998) 121 -131 14

Combined Analysis (CE – β Decay) Fujita et al PRL 95 (2005) 212501 In β decay In charge exchange j A precise value of the parent half-life is very important!!! 15

T 1/2 analysis of 54 Ni g. s nuclei was done using heavy ion implantation-beta correlations for identified 54 Ni 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 16

T 1/2 analysis of 54 Ni g. s nuclei was done using heavy ion implantation-beta correlations for identified 54 Ni ions produced and implantaion beta-gamma correlations. HI-beta Each decay was correlated with all implants correlations happening before and pixel after the decay same To assure no-systematic errors and well defined background Background. HI-beta normalised correlations opposite pixel 17

Least square fit 18

Parent Experimental value of the ground state to ground state feeding estimation ? T 1/2 =114. 20. 3 T 1/2 =114. 71. 7 Systematic errors such as beta efficiency error or survival probability errors cancels!, only gamma efficiency counts!!! Experimental Result g. s. feed 54 Ni =0. 792 19

Comparison of “g. s to g. s feeding” estimated from Fermi transition probability and our experimental result 0+ 1+ 1+ 1+ Tz=-1 This is a super-allowed 0+ 0+ Fermi transition with B(F)=N-Z And hence st 1+ 0+ , IAS Tz=0 t Parent Fermi estim Exp. G. s feed 54 Ni 0. 82(3) 0. 79(2) 50 Fe 0. 74(4) 0. 74(2) 50 Cr 0. 78(1) 0. 77(2) 42 Ti 0. 49(1) 0. 44(4) 20

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

M 1 transitions from T=0 to T=0 in self-conjugate nuclei are strongly suppressed!!!! Strongly supressed allpwed 1+ 1+ 1+ 0+ T=0 Tz=-1 T=0 st 2+ T=1 1+ T=0 0+ T=1 t IAS Tz=0 22

Results: BGT 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 BGT symmetry in the f shell. These cases are specially “clean” since they involve only f 7/2 to f 7/2 and f 7/2 to f 5/2 B. Rubio kind of transitions 23 and we compare only the two gs states Brighton 12 -13 Jan 2011

summary We have studied the beta decay of four Tz=-1 nuclei in the f 7/2 shell They were all produce in fragmentation of 58 Ni beams In spite of the complex set-up we could get extremely clean results Very accurate T 1/2 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. B. Rubio ONE CAN PERFORME DELICATE SPECTROSCOPY STUDIES IN FRAGMENTATION Brighton 12 -13 Jan 2011 24 REACTIONS IF ONE ACHIEVES CLEAN IMPLANTATION

FIN B. Rubio Brighton 12 -13 Jan 2011 25

Results: BGT 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 BGT symmetry in the f shell. These cases are specially “clean” since they involve only f 7/2 to f 7/2 and f 7/2 to f 5/2 kind of transitions and we compare only the two gs states B. Rubio Brighton 12 -13 Jan 2011 26

Esta es la última tabla que me entregó Pancho sin errors en los valores de CE B. Rubio Brighton 12 -13 Jan 2011 27

B. Rubio Brighton 12 -13 Jan 2011 28

N= Z Luckly enough we have all Stable targets in the f shell Z=28 β+ or β- Z=20 N=28 B. Rubio N=20 Brighton 12 -13 Jan 2011 29

Absolute BGT 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 (3 He, t) We set up a series of experiments to test this idea B. Rubio Brighton 12 -13 Jan 2011 30

T 1/2 analysis of 54 Ni g. s nuclei was done using heavy ion implantation-beta correlations for identified 54 Ni ions produced and implantaion beta-gamma correlations. Possible systematic errors a) Deadtime b) contaminants HI-beta Each decay was correlated with all implants correlations happening before and pixel after the decay same To assure no-systematic errors and well defined background HI-beta correlations opposite pixel 31

Maximum likelihood fit 32

T 1/2 from gammas 46 Cr missing 33

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

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Results: preliminary BGT values from beta decay A=54 B(GT) decay B(GT) CE 937 ke. V 0. 471(55) 0. 493(62) 3378 ke. V 0. 074(14) 0. 079(11) 3889 ke. V 0. 064(17) 0. 103(14) 4544 ke. V 0. 075(27) 0. 147(20) A=50 652 ke. V 0. 547(90) 0. 510(14) 2404 ke. V 0. 126(23) 0. 151(40) 2685 ke. V 0. 090(19) 0. 106(28) 3380 ke. V 0. 281(55) 0. 350(93) 994 ke. V 0. 330(329) 0. 368(44) 1433 ke. V 0. 107(107) 0. 122(15) 2462 ke. V 0. 146(146) 0. 201(24) 2698 ke. V 0. 111(111) 0. 205(25) 2978 ke. V 0. 479(478) 0. 625(75) 3870 ke. V 0. 105(119) 0. 117(14) A=46 Isospin symmetry works in general (full strength) but some differences appear at high excitation energy, which should be understood Large B(GT) uncertainties are due to the errors in the beta decay half-life. A better value should come from the present experiment. This is the first experimental test of BGT symmetry in the f shell. These cases are specially “clean” since they involve only f 7/2 to f 7/2 and f 7/2 to f 5/2 Francisco Molina kind of transitions B. Rubio Brighton 12 -13 Jan 2011 37 and we compare only the two gs states Analysis in progress IFIC(Valencia)

B. Rubio 5921 (1+) 4828 (1+) 4550 (1+) 3895 (1+) 0+ 1+ 1+ 0+ 3377 (1+) Brighton 12 -13 Jan 2011 1+ 0+ 4550 (1+) First 4 th GT States till 4. 5 Me. V were seen by beta decay 347 counts 3895 (1+) 94448 counts 2598 counts 1+ 0+937 (1+) 1+ 9402 counts 1816 counts 3377 (1+) 0+ 0+ 937 (1+) 1+ A=54, T=1 Beta Decay Results and comparison with CE 150 counts 38

B. Rubio 652 (1+) 1+ Brighton 12 -13 Jan 2011 0+ 1+ 0+ 3392 (1+) 0+ 2694 (1+) 2411 (1+) 0+ First 4 th GT States till 3. 3 Me. V were seen by beta decay 1+ 1+ 0+ 5728 (1+) 0+ 4332 (1+) 0+ 1+ 1+ 3392 (1+) 0+ 1+ 1+ 3654 (1+) 0+ 2694 (1+) 1+ 652 (1+) 1+ 2411 (1+) 0+ A=50, T=1 39

B. Rubio 0+ T. Adachi et al. , PRC 73, 024311 (2006). Brighton 12 -13 Jan 2011 0+ 0+ 0+ 2978 (1+) 2697 0+(1+) 1+ 1+ All the GT States were seen by beta decay 1+ 1+ 2460 (1+) 3870 (1+) 1+ 994 (1+) 1+ 1432 (1+) 0+ 1+ 1+ 0+ 0+ 1+ 1+ 1+ 0+ 1+ 2978 (1+) 0+ 0+ 3870 (1+) 2461 (1+) 2699 (1+) 1433 (1+) 994 (1+) 0+ A=46, T=1 40

RISING Efficiency Simulation Rising Ge simulation Including + Si + Box 2. 26% y = p 0+p 1*x + p 2*x 2 + p 3*x 3 +p 4*x 4+p 5*x 5 , y=log(eff) and x=log(E) Z. Hu et al. : Nucl. Instr. and Meth. In Phys. Res. A 419 (1998) 121 -131 41

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B. Rubio Brighton 12 -13 Jan 2011 5728 1+ 4332 1+ 3654 1+ 2694 1+ 3392 1+ 2411 1+ 1+ 1+ 44

1+ 1+ 1+ B. Rubio 1+ Brighton 12 -13 Jan 2011 45