Recent Results in Fragmentation Isomer Spectroscopy with RISING

1. Recent Results in Fragmentation Isomer Spectroscopy with RISING Paddy Regan Dept. of Physics University of Surrey Guildford, GU2 7XH, UK p.regan@surrey.ac.uk

2. Major campaign using ‘retired EUROBALL’ cluster detectors • for fragmentation-based nuclear spectroscopy. • Stopped-Beam Campaign to • study decays from isomers and • following beta-decay. • Three experiments for ‘isomer only’ part ran in Feb/Mar’06 • N=Z~43 nuclei (107Ag beam, PHR) • N=126, ‘south’ ( 208Pb beam, Zsolt Podolyák) • 54Ni/54Fe isospin symmetry (58Ni beam, Dirk Rudolph) • To run in July 2006, • 130Cd isomers (136Xe beam, Andrea Jungclaus) • 130Cd via fission (238U beam, Magda Gorska) • Fission fragments for A~110 (238U beam, Alison Bruce) • ‘Active stopper’ expts for 2007 (N~126, 170Dy, Tz=-1.)

3. In-Flight Technique Using Projectile Fragmentation Production target Central focus, S2 Final focus, S4 primary beam Pb @ 1GeV/u dipole, Br degrader degrader MW=x,y scint catcher scint DE(Z2) scint (veto) Use FRS@GSI or LISE3@GANIL to ID nuclei. Transport some in isomeric states (TOF~ x00ns). Stop and correlate isomeric decays with nuclei id. eg. R. Grzywacz et al. Phys. Rev. C55 (1997) p1126 ⇨ LISE C.Chandler et al. Phys. Rev. C61 (2000) 044309 ⇨ LISE M. Pfützner et al. Phys. Lett. B444 (1998) p32 ⇨ FRS Zs. Podolyak et al. Phys. Lett. B491 (2000) p225 ⇨ FRS M. Pfützner et al. Phys Rev. C65 (2002) 064604 ⇨ FRS M. Caamano et al., Eur.Phys. J. A23 (2005) p201 ⇨ FRS

4. 208Pb beam at 1 GeV/u allows production of ( high-spin isomers, M. Pfützner et al. Phys Rev. C65 (2002) 064604 High spins (>35/2) populated

6. CHICO + GS data 136Xe + 198Pt

7. Stopped Rising Array @ GSI: 15 x 7 element CLUSTERs Photopeak efficiency 15-17% at 1.3 MeV

10. Neutrons: Tzn=+1/2 Protons: Tzp=-1/2 Isospin Tz=1/2(N-Z) T=|Tz| • Protons and Neutrons are 2 states of the same particle • Pauli principle prevents T=0 states for nn and 2He • Deuteron (T=0,S=1) is the only A=2 bound system Adapted from R.Casten, Nuclear Structure from a Simple Perspective (2000)

11. Long standing problem…. • studies of N=Z nuclei and • T=0, T=1 competition. • One can obtain spectroscopic • info. from isomeric states

12. Summary of odd-odd N=Z Spectroscopy (to Mar. 06) 62Ga : S.M. Vincent al al., Phys. Lett. 437B (1998) 264 D. Rudolph et al., Phys. Rev. C69 (2004) 034309 66As: R. Grzywacz et al., Nucl. Phys. A682 (2001) 41c R. Grzywacz et al., Phys. Lett. 429B (1998) 247 70Br: M. Karny et al., Phys. Rev. C70 (2004) 014310 D.G. Jenkins et al., Phys. Rev. C65 (2002) 0644307 G. DeAngelis et al., Eur. Phys. J. A12 (2001) 51 74Rb: C.D. O’Leary et al., Phys. Rev. C67 (2003) 021301 D. Rudolph et al., Phys. Rev. Lett. 76 (1996) 376 78Y ? 82Nb ? p3n reactions, b-delayed tagging ? 86Tc: C. Chandler et al., Phys. Rev. C61 (2000) 044309 Ip=0+ T=1 ground states from b-decay for 74Rb, 78Y, 82Nb, 86Tc and 90Rh J. Garces Narro et al., Phys. Rev. C63 (2001) 044307 T. Faestermann et al., Eur. Phys. J. A15 (2002) 185

14. T=0,1 Competition in N=Z nuclei Spins of the GS in odd-odd N=Z nuclei can help identify which mode is dominant With increasing mass there is competition between T=0 and T=1 collective modes From A. Garnsworthy

15. Heaviest odd-odd, N=Z gammas, isobaric analog states ? GANIL (fragmentation ‘pick up’) 86Tc from 92Mo beam, C. Chandler et al. Phys. Rev. C61 (2000) 044309

16. Nilsson orbitals Likely configurations of 86Tc ms isomer Both p and n in either/or 5/2+[422] or 5/2-[303] This would give the isomer spin 5+ (or perhaps 5- ?) Would not likely decay by to the T=1 4+ due to selection rule for E1 between T=0 and T=1 states. From A. Garnsworthy

17. 86Tc 86Mo Previously Proposed Structure of 86Tc from GANIL expt. data • Ground state spin assignment inferred through Fermi super allowed β-decay half life (see J Garces Narro et.al., Phys. Rev. C 63 (2001) 044307) • All other information is uncertain From A. Garnsworthy

18. S. Pietri et al., RISING data 107Ag beam

19. 88Zr S. Pietri et al., 107Ag beam

20. Ip=12+ isomer N. Marginean et al., PRC67 (2003) 061301 S. Pietri et al., 107Ag beam RISING Mar’06

21. A.B. Garnsworthy et al.,

22. A.B. Garnsworthy et al.,

23. The Proposed Structure of 86Tc Dl, Dj=3 ? g9/2 x p3/2 850 keV E3 = 8.35x10-6 s 270 keV M2 = 1.1x10-6 s 581 keV M1 = 3.1x10-14 s A.B. Garnsworthy et al., preliminary

24. SM calcs by H. Grawe (GSI)

25. New Data point

26. 62Ga 66As 70Br 86Tc 74Rb E(2+) for odd-odd N=Z T=1 states follows e-e trend withb2

27. 208Pb region SUPER-FRS Yields 217Ac, 29/2+, 1μs 215Ra, 43/2-, 800ns 212Po, 18+, 65s many μs isomers expected N=126, holes in 208Pb

29. Gamma-gamma analysis on 200Pt isomer (21 ns!), M. Caamano et al. Nucl. Phys. A682 (2001) p223c; Acta Phys. Pol. B32 (2001) p763 stripping effect to extend lifetime

30. 206Hg (Z=80) is the • most ‘neutron-rich’ N=126 • even-even isotope with • structural information to • date….how robust is the • N=126 shell ? • Look at isomeric B(Ml) • for seniority isomers based • on proton (h11/2)-n states. B. Fornal et al., Phys. Rev. Lett. 87 (2001) 212501

31. 10+ isomer 206Hg isomers, N=126, S. Steer, Zs. Podolyak et al., 208Pb RISING 5- isomer Relative isomeric ratios give insight into cold proton ‘knockout’ theory see J. Tostevin AIP Conf. Proc. 819 (2006) p523.

32. Ip=10+ isomer, 2 proton cold knockout from h11/2 orbitals. (< 100 ns half-life). S. Steer, Zs. Podolyak et al., 208Pb fragmentation, RISING Mar’06

33. New isomer in 204Pt !! 4 proton holes in 208Pb double magic closed shell !! S. Steer, Zs. Podolyak et al., 208Pb fragmentation RISING Mar’06

34. Podolyàk, Steer et al., 208Pb frag. RISING @ GSI Mar’06 March’06 RISING data N=126, 4 proton holes

35. 54Ni 10+ isomer (mirror of 54Fe)…..proton activity….. D. Rudolph et al., 58Ni fragmentation RISING Mar.’ 06 See Mike Bentley’s talk for more details on this ‘beauty!’

36. Dirk Rudolph et al., Feb/Mar ’06 RISING