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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. Major campaign using ‘retired EUROBALL’ cluster detectors for fragmentation-based nuclear spectroscopy.
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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
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.)
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
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
CHICO + GS data 136Xe + 198Pt
Stopped Rising Array @ GSI: 15 x 7 element CLUSTERs Photopeak efficiency 15-17% at 1.3 MeV
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)
Long standing problem…. • studies of N=Z nuclei and • T=0, T=1 competition. • One can obtain spectroscopic • info. from isomeric states
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
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
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
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
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
S. Pietri et al., RISING data 107Ag beam
88Zr S. Pietri et al., 107Ag beam
Ip=12+ isomer N. Marginean et al., PRC67 (2003) 061301 S. Pietri et al., 107Ag beam RISING Mar’06
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
62Ga 66As 70Br 86Tc 74Rb E(2+) for odd-odd N=Z T=1 states follows e-e trend withb2
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
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
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
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.
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
New isomer in 204Pt !! 4 proton holes in 208Pb double magic closed shell !! S. Steer, Zs. Podolyak et al., 208Pb fragmentation RISING Mar’06
Podolyàk, Steer et al., 208Pb frag. RISING @ GSI Mar’06 March’06 RISING data N=126, 4 proton holes
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!’
Dirk Rudolph et al., Feb/Mar ’06 RISING