1. Recoil-beta tagging David Jenkins

2. Odd-odd N=Z Fascinating laboratory for studying interplay of T=0 and T=1 states Very unusual low level density for odd-odd nuclei e.g. only 1 state below 1 MeV in 70 Br Evidence for np-pairing in both low lying states and high spin rotational bands Beta decays important for standard model tests - CVC hypothesis

3. How to study odd-odd N=Z  Nuclei are difficult to produce without reactions close to 40 Ca+ 40 Ca at near-barrier energies  Production cross-sections are low (<1% of total cross-section)  Residues are too slow at focal plane of separator e.g. FMA to use ion chamber to identify Z  Most measurements done with neutron detectors + charge particle detectors to select e.g. pn or  pn channel  Nuclei are difficult to produce without reactions close to 40 Ca+ 40 Ca at near-barrier energies  Production cross-sections are low (<1% of total cross-section)  Residues are too slow at focal plane of separator e.g. FMA to use ion chamber to identify Z  Most measurements done with neutron detectors + charge particle detectors to select e.g. pn or  pn channel

4. Recoil-decay tagging

5. Recoil-beta tagging

6. RITU+GREAT

7. Test case: 74 Rb

8. Proof-of-principle  nat Ca ( 36 Ar, pn) 74 Rb  E beam = 103 MeV  τ ½ ( 74 Rb) = 65 ms  β + endpoint ~ 10 MeV  σ ~ 10 μb  nat Ca ( 36 Ar, pn) 74 Rb  E beam = 103 MeV  τ ½ ( 74 Rb) = 65 ms  β + endpoint ~ 10 MeV  σ ~ 10 μb

9. High energy positrons

11. Identification of 74 Rb A.N. Steer, et al., NIM A565, 630 (2006)

12. 74 Rb level scheme from RBT

13. Unknown case: 78 Y  Nothing known about 78 Y except 0+ superallowed decay and (5+) beta- decaying isomer  RBT technique applied using 40 Ca( 40 Ca,pn) 78 Y reaction  Cross-section should be very similar to 74 Rb  90% of flux proceeds to low-lying isomer  Isomer is too long-lived for effective tagging  Nothing known about 78 Y except 0+ superallowed decay and (5+) beta- decaying isomer  RBT technique applied using 40 Ca( 40 Ca,pn) 78 Y reaction  Cross-section should be very similar to 74 Rb  90% of flux proceeds to low-lying isomer  Isomer is too long-lived for effective tagging

14. B.S. Nara Singh et al., Phys. Rev. C (accepted)

15. CEDs for A~70 Difference in np and NN pairs gives CED rise of ~12 keV/J Uniform upward trend for deformed nuclei except: A=78 - flat A=70 - strongly down A=70 data from G. de Angelis, EPJ A12, 51 (2001) and D.G. Jenkins et al., PRC 65, 064307 (2002) CED(J)=E x (J,T=1,T z )

16. Effect of shape change  2 =-0.3  2 =0.35  2 =0.18  2 =0.35  CED=-7 keV  CED=-75 keV R. Sahu et al., J. Phys. G 13, 603 (1987) TRS calculations: T. Mylaeus et al., J. Phys. G 15, L135 (1989) Coulomb energies calculated after S. Larsson, Phys. Scri 8, 17 (1973).

17. Plans for future measurements  Recoil-beta-tagging:  Search for T z =-1 nuclei e.g. 70 Kr, 74 Sr using double-beta-tagging  Study mirror symmetry in A=71 i.e. 71 Kr  Search for 0 + in 74 Rb and compare B(E0) with 74 Kr  Use vacuum-mode recoil separator to select by mass and improve rates  Recoil-beta-tagging:  Search for T z =-1 nuclei e.g. 70 Kr, 74 Sr using double-beta-tagging  Study mirror symmetry in A=71 i.e. 71 Kr  Search for 0 + in 74 Rb and compare B(E0) with 74 Kr  Use vacuum-mode recoil separator to select by mass and improve rates

18. RBT Collaboration B.S. Nara Singh 1, A.N. Steer 1, D.G. Jenkins 1, R. Wadsworth 1, P. Davies 1, R. Glover 1, N.S. Pattabiraman 1, T. Grahn 2, P.T. Greenlees 2, P. Jones 2, R. Julin 2, M. Leino 2, M. Nyman 2, J. Pakarinen 2, P. Rahkila 2, C. Scholey 2, J. Sorri 2, J. Uusitalo 2, P.A. Butler 3, M. Dimmock 3, R. D. Herzberg 3, D.T. Joss 3, R.D. Page 3, J. Thomson 3, R. Lemmon 4, J. Simpson 4, B. Blank 5, B. Cederwall 6, B. Hadinia 6, M. Sandzelius 6 Department of Physics, University of York, Heslington, York YO10 5DD, UK Department of Physics, University of Jyväskylä, P.O. Box 35, FIN-40351, Jyväskylä, Finland Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE, UK CCLRC Daresbury Laboratory, Keswick Lane, Warrington WA4 4AD, UK Centre d’Etudes Nuclèaires de Bordeaux-Gradignan, F-33175 Gradignan Cedex, France Royal Institute of Technology, Roslagstullsbacken 21, S-106 91 Stockholm, Sweden.