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New Insights into Nuclear Structure at Extremes of Isospin usng the Stopped RISING Array at GSI

Paddy Regan for the Stopped Beam Rising Collaboration Dept. of Physics, University of Surrey Guildford, Surrey, GU2 7XH, UK p.regan@surrey.ac.uk. New Insights into Nuclear Structure at Extremes of Isospin usng the Stopped RISING Array at GSI. RISING R are I sotopic S pectroscopic

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New Insights into Nuclear Structure at Extremes of Isospin usng the Stopped RISING Array at GSI

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  1. Paddy Regan for the Stopped Beam Rising Collaboration Dept. of Physics, University of Surrey Guildford, Surrey, GU2 7XH, UK p.regan@surrey.ac.uk New Insights into Nuclear Structure at Extremes of Isospin usng the Stopped RISING Array at GSI

  2. RISING Rare Isotopic Spectroscopic INvestigations @ GSI = 15 x Cluster germaniums for (the most) exotic gamma-ray spectroscopy

  3. Physics aims of the RISING stopped beam campaign 204Pt, N=126 ~190W, Terra Incognita 82Nb,86Tc 130Cd, N=82 54Ni 106Zr

  4. Stopped RISING Physics Aims • Study the evolution of single-particle / shell structure (shell melting ?) as a function of N:Z ratio. • 56Ni (N=28 ; Z=28) Emma Johannson Mon. 7.50pm • 100Sn (N=50: Z=50) • 132Sn (N=82 : Z=50) Juergen Gerl, Tues. 11.30am • 208Pb (N=126 : Z=82) Steve Steer, poster • Spin input in fragmentation. Stephane Pietri, poster • High(est) spins in projectile fragmentation Juergen Gerl, Tues. 11.30am • Study the structure of nuclei with the most exotic proton-to-neutron ratios: • Proton drip-line N=Z Adam Garnsworthy, poster • (Very) neutron-rich, Jurgen Gerl, Tues. 11.30am • Nuclear ‘symmetries’ and relevance of quantum numbers: • Isospin, T (N:Z ratio) • Nuclear Deformation,b2 (p-n interactions) • Angular Momentum Projection, K (axial symmetry) • Critical Point Symmetries e.g., X(5)

  5. Accelerator facility at GSI The Accelerators: • UNILAC(injector) E=11.4 MeV/n • SIS 18Tmcorr. U 1 GeV/n Beam Currents: 238U - 108 pps some medium mass nuclei- 109 pps (A~130) FRS provides secondary radioactive ion beams: • fragmentation or fission of primary beams • high secondary beam energies: 100 – 700 MeV/u • fully stripped ions

  6. Ion-by-ion identification with the FRS TOF E Cocktail of secondary, exotic fragments with ~ x00 MeV/u thru. FRS. Separate and identify event-by-event. Chemically independent.

  7. Stopped RISING Array @ GSI: 15 x 7 element CLUSTERs Photopeak efficiency >10% at 1.3 MeV. XIA-DGF electronics

  8. 40  detection efficiency 30 DGF TDC 20 Absolute efficiency [%] 10 MSU GSI 0 0 200 600 1000 1400 -energy [keV] The RISING -ray spectrometer 15 EUROBALL Cluster (105 Ge crystals) digital signal processing via 30 XIA DGF modules S. Pietri et al., in press NIM B + poster very high -ray efficiency high granularity (prompt flash problem) Best-spectrometer ever used in isomer spectroscopy !

  9. High granularity of RISING reduces ‘prompt flash’ problems….~ 7/105… DGF timing of flash, comparable to former ‘analog’ timing. S. Pietri et al., in press NIM B (2007)

  10. (pg9/2)-2,4I=14+ (ng9/2)-2,4I=14+ Ip=12+ isomer N. Marginean et al., PRC67 (2003) 061301 (pg9/2)-2I=8+ + (ng9/2)-2I=8+ + S. Pietri et al., Nucl. Inst. Meth. B. in press. (2007)

  11. Physics aims of the RISING stopped beam campaign 204Pt ~190W, Terra Incognita 130Cd 82Nb,86Tc 54Ni 106Zr

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

  13. T=0, 1 Competition in Deformed N=Z odd-odd Nuclei • Use projectile fragmentation to populate exotic N=Z=41,43 nuclei 82Nb , 86Tc. • Measure gammas from isomeric decays. • Construct (partial) decay schemes • Look for energy competition between T=1 (Ip=0+) and T=0 (Ip=1+ ?) lowest states.

  14. Neutron-Proton Pairing T=1 and T=0 Residual Interactions Ground state angular momentum can be 0+, Jmin or Jmax Structure of Odd-Odd N=Z Nuclei Even-even core plus one valence proton and one valence neutron in equivalent orbits

  15. T=1: Ip=0+ New Data point T=0 : Ip=1+or (2j)+ E (T=0 – T=1) (keV) ?

  16. 82Nb 86Tc T1/2= 133(20) ns T1/2= 1.59(20) s A.B. Garnsworthy, submitted to PRL

  17. Level structure of 82Nb and 86Tc compared to their TZ=+1 isobars T=1 T=1 (T=0) T=1 T=1 (T=0) 82Zr 82Nb 86Mo 86Tc A. Garnsworthy et al., submitted to PRL

  18. A.B. Garnsworthy et al., submitted to PRL

  19. * 128 keV M1 in 82Nb gives fn=18. First Isospin changing K isomer? *Note, E2 conversion for 128 keV would give unphysical IR~200%.

  20. Mapping isospin symmetry across the fpg shell.

  21. Physics aims of the RISING stopped beam campaign 204Pt 130Cd 82Nb,86Tc 54Ni 106Zr

  22. Active Stopper RISING • Isomer spectroscopy requires isomers! • Would like to be able to do beta-delayed spectroscopy on (neutron-rich) fragments. • Problem….implanting ~10 GeV energy followed by ~200 keV in same pixel. • Solution? ‘Logarithmic’ pre-amps.

  23. 5 cm x 5 cm DSSSD (16 strips by 16 strips = 256 pixels) 3 positions across focal plane, room for 2 detectors deep.

  24. R. Kumar et al.,

  25. 190W isomer decay from 208Pb beam (poster by G. Farrelly).

  26. 207 keV 2+ → 0+ On-line beta-delayed gated 190Ta ions….. Transitions fed in daughter 190W nucleus by beta decay. First time we see same nucleus via both isomer decay AND beta-decay. N. Al-Khomashi, PhD thesis

  27. β-delayed γ-rays in 192W – Decay of 192Ta

  28. 190W 188W 192W P.D. Stevenson et al., Phys. Rev. C72(2005) 047303

  29. 192Ta 190Ta 188Ta 198Ir 202Ir 203Au 205Au 194Re

  30. Summary of Stopped RISING to Date • 2006 passive stopper (isomer) experiments • N~Z isomers, isospin symmetry/pairing studies around 56Ni (Rudolph) and highly deformed A~80 N=Z (PHR). • N~126 seniority isomers (204Pt) (Podolyak) • Neutron-rich ~ 132Sn nuclei with 136Xe fragmentation (Jungclaus) and 238U projectile fission (Gorska,Pfutzner) • A~110 fission fragment isomers (Bruce) • ‘Active Stopper’ campaign I (March 2007) • N=126, 205Au M4 (Z=82 holes) electron conversion • Beta-delayed spectroscopy, 188,190,192Ta → 188,190,192W • ‘Active Stopper’ campaign II (July 2007) • N=126 part II (J. Benlliure et al.,) • A~50/60 N=Z decays (Gadea, Rubio, Gelletly & Fujita)

  31. First Results from the Stopped RISING Campaign at GSI: • The Mapping of Isomeric Decays in Highly Exotic Nuclei P.H.Regan1, A.B.Garnsworthy1,2, S.J.Steer1, S.Pietri1, Zs.Podolyák1, D.Rudolph3, M.Górska4, L.Caceres4,5, E.Werner-Malento4,6, J.Gerl4, H.J.Wollersheim4, F.Becker4, P.Bednarczyk4, P.D.Doornenbal4, H.Geissel4, H. Grawe4, J.Grębosz4,7, R.Hoischen3, A.Kelic4, I.Kojouharov4, N.Kurz4, F.Montes4, W.Prokopowicz4, T.Saito4, H.Schaffner4, S.Tashenov4, A.Heinz2, M.Pfützner6, T.Kurtukian-Nieto8, G.Benzoni9, M.Hellström2, A.Jungclaus5, L.-L.Andersson3, L.Atanasova10, D.L.Balabanski11, M.A.Bentley12, B.Blank13, A.Blazhev14, C.Brandau1,4, J.Brown12, A.M.Bruce15, F.Camera9, W.N.Catford1, I.J.Cullen1, Zs.Dombradi16, E.Estevez8, C.Fahlander3, W.Gelletly1, G.Ilie14, E.K.Johansson3, J.Jolie14, G.A.Jones1, M.Kmiecik7, F.G.Kondev17, S. Lalkovski10,15, Z.Liu1, A.Maj7, S.Myalski7, S.Schwertel18, T.Shizuma1,19, A.J.Simons1, P.M.Walker1, O. Wieland9 1Dept. of Physics, University of Surrey, Guildford, GU2 7XH, UK 2WNSL, Yale University, New Haven, CT 06520-8124, USA 3Department of Physics, Lund University, S-22100 Lund, Sweden 4GSI, Planckstrasse 1, D-64291, Darmstadt, Germany 5Departamento de Fisica Teórica, Universidad Autonoma de Madrid, E-28049, Madrid, Spain 6IEP Warsaw University, Hoźa 69, PL-00-681 7The Henryk Niewodniczański Institute of NuclearPhysics, PL-31-342, Kraków, Poland 8Universidad de Santiago de Compostela, E-15706, Santiago de Compostela, Spain 9INFN, Universitá degli Studi di Milano, I-20133, Milano, Italy 10Faculty of Physics, University of Sofia, BG-1164, Bulgaria & The Institute for Nuclear Research, Bulgarian Academy of Science, BG-1784, Sofia, Bulgaria 11Dipartimento di Fisica, Universit ´a di Camerino, I-62032, Italy 12Dept. of Physics, University of York, Heslington, York, Y01 5DD, UK 13CENBG, le Haut Vigneau, Bordeaux, F-33175, Gradignan Cedex, France 14IKP, Universit¨at zu Köln, D-50937, Köln, Germany 15School of Engineering, University of Brighton, Brighton, BN2 4GJ, UK 16Institute for Nuclear Research, Debrecen, H-4001, Hungary 17Nuclear Engineering Division, Argonne National Laboratory, Argonne IL-60439, USA 18Physik Department E12, Technische Universität München, Garching, Germany 19Japan Atomic Energy Agency, Kyoto, 619-0215, Japan

  32. Workshop on RISING Physics Madrid 6-8 November 2006

  33. Shell structure south of 208Pb Spokesperson: Zsolt Podolyak, Surrey cold fragmentation of 208Pb@1 GeV/u 204Pt See Jeff Tostevin for related reaction theory 202Os main aim: spectroscopy of N=126 isotones 206Hg, 204Pt and 202Os

  34. Steer, Podolyak et al., to be submitted to PRL

  35. 204Pt populated via 4-proton-knockout from 208Pb long isomer: T1/2=8.41(16) s short isomer: T1/2=152(16) ns

  36. 204Pt Z=78 Z. Podolyak, S. Steer et al., PRL, in preparation h11/2-2 152(16) ns d5/2-1h11/2-1 d3/2-1h11/2-1 ? s1/2-1h11/2-1 8.41(16) s d3/2-1d5/2-1 s1/2-1d3/2-1 SM B. Fornal et al. PRL 87 (2001)212501 Results require modification of SPE and/or interactions ! N=126 isotones: (h11/2)-2,4 I=10+ isomers 206Hg Z=80 92(8) ns 2.15(21) s SM

  37. 205Au126 electron conversion!! h11/2 → d3/2M4 transition (half-life a few seconds…..) New single particle (hole) information around 208Pb core. K L

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