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Paddy Regan for the Stopped Beam Rising Collaboration Dept. of Physics, University of Surrey p.regan@surrey.ac.uk

Paddy Regan for the Stopped Beam Rising Collaboration Dept. of Physics, University of Surrey p.regan@surrey.ac.uk. The (Stopped Beam) RISING Experimental Campaign at GSI: The Mapping of Isomeric Decays and Beta-Delayed Spectroscopy in Highly Exotic Nuclei. RISING

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Paddy Regan for the Stopped Beam Rising Collaboration Dept. of Physics, University of Surrey p.regan@surrey.ac.uk

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  1. Paddy Regan for the Stopped Beam Rising Collaboration Dept. of Physics, University of Surrey p.regan@surrey.ac.uk The (Stopped Beam) RISING Experimental Campaign at GSI: The Mapping of Isomeric Decays and Beta-Delayed Spectroscopy in Highly Exotic Nuclei

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

  3. Stopped RISING Physics Aims & Philosophy • Study the evolution of single-particle / shell structure (shell melting ?) as a function of N:Z ratio. • 56Ni (N=28 ; Z=28) 100Sn (N=50: Z=50) • 132Sn (N=82 : Z=50) • 208Pb (N=126 : Z=82) • Study the structure of nuclei with the most exotic proton-to-neutron ratios: • Proton drip-line N=Z • Neutron-rich ‘terra incognita’. • 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) • Reaction mechanism studies in fragmentation.

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

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

  6. 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., Acta Phys. Pol.B38 (2007)p1255 very high -ray efficiency high granularity (prompt flash problem) Best-spectrometer ever used in isomer spectroscopy !

  7. N=Z line Particle Identification Sum of data from 90Rh, 86Tc and 82Nb settings with 107Ag beam A.B. Garnsworthy et al., Acta Phys. Pol. B38 (2007) p1265 & L. Caceres et al., Acta Phys. Pol. B38 (2007) p1271

  8. 82Nb 86Tc T1/2= 133(20) ns T1/2= 1.59(20) s

  9. Search for the 8+ (g9/2)-2 seniority isomer in 130Cd 6-proton-knockout from 136Xe: A. Jungclaus fission of 238U: M. Górska, M. Pfützner June/July 2006 two proton holes in the g9/2 orbit g9/2 M. Górska et al., Phys. Rev. Lett. 79 (1997)

  10. Singles -spectrum in delayed coincidence with implanted 130Cd ions T1/2=220(30) ns ENERGY TIME

  11.  coincidence spectra 539 138 1325 128 2207 8+ (8+) 6+ (6+) 2094 4+ (4+) Gate: 128 keV 1889 539 2+ (2+) Gate: 138 keV 1346 Gate: 539 keV 1325 Gate: 1325 keV 0+ 0+ 130Cd82 SM 48 Decay of the 8+ isomer in 130Cd T1/2=220(30)ns T1/2=173ns New results give no evidence for a N=82 shell quenching A. Jungclaus, L. Cáceres et al.,submitted to Nature

  12. Shell structure south of 208Pb Spokesperson: Zsolt Podolyak, Surrey cold fragmentation of 208Pb@1 GeV/u 204Pt Related reaction theory by J.Tostevin et al., 202Os main aim: spectroscopy of N=126 isotones 206Hg, 204Pt and 202Os

  13. 204Pt populated via 4-proton-knockout from 208Pb long isomer: T1/2=8.41(16) s short isomer: T1/2=152(16) ns S. Steer, Zs. Podolyak et al., Acta Phys. Pol. B38 (2007) p1283

  14. 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

  15. 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.

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

  17. R. Kumar et al.,

  18. 205Au126 electron conversion!! h11/2 → d3/2M4 transition (half-life a few seconds…..) New single particle (hole) information around 208Pb core. K L

  19. 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

  20. 190W isomer decay from 208Pb beam

  21. GSI-EA (Fri. 20th April 2007) 11 New Stopped RISING Proposals All with UK involvement, 4 with UK (co)spokespersons)

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