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Saclay, 30 January 2007 Rauno Julin Department of Physics University of Jyväskylä FinlandJYFL In-beam Spectroscopy of In-beam Spectroscopy of Transfermium Nuclei Transfermium Nuclei
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Outline: Introduction Even-Even 254 No ( Z =102, N = 152 ) 250 Fm ( Z =100, N = 150 ) Odd-Proton 251 Md (Z = 101, N = 150) 255 Lr (Z = 103, N = 152) Odd-Neutron 253 No (Z = 102, N = 151) Future plans
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Spectroscopy of very neutron deficient and heavy nuclei at JYFL Can be produced via fusion evaporation with stable-ion beams and stable targets Can be produced via fusion evaporation with stable-ion beams and stable targets Short-living alpha or proton emitters → tagging methods Short-living alpha or proton emitters → tagging methods Cross-sections down to 1 nb Only levels near the yrast line populated
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Recoil – Decay –Tagging (RDT) method
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JUROGAM 43 Ge + BGO Eff. 4% RITU Gas-filled recoil separator Transmission 20-50 % GREAT Focal plane spectrometer TDR Total Data Readout Triggerless data acquisition system with 10 ns time stamping + GRAIN the Analyser RDT Instrumentation at JYFL
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prompt e - SACRED electron spectrometer at the RITU target
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Transfermium Nuclei Produced in asymmetric cold-fusion reaction – X( 48 Ca,2n)Y → ideal for the gas-filled separator RITU → Only one reaction channel open → Total compound cross-section down to 50 mb → I beam up to 30pnA on a 0.5mg/cm 2 target in in-beam runs Fission dominates: 100000 : 1 → I beam limited by the Ge rate → Very low focal-plane rate → Enables long t 1/2 – α – tagging
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254 No Z = 102, N = 152
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254 No 842 943 In-beam γ - rays from 208 Pb( 48 Ca,2n) 254 No - 2µb JUROGAM + RITU S. Eeckhaudt et al. EPJ A26, (2005), 227
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In-beam γγ coincidences from 254 No 254 No ?
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254 No-recoil gated in-beam conversion electrons from 208 Pb( 48 Ca,2n) 254 No Discrete lines + M1 continuum M1 P.A. Butler at al. PRL 89 (2002) 202501 SACRED + RITU data 254 No
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254 No Levelscheme Long isomer Short isomer 3+ 8- (16+) 55 s R.-D. Herzberg et al. Nature 442, 896-899 (24 August 2006)
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250 Fm Z = 100, N = 150
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Singles Gamma-Ray Spectra from 204 Hg( 48 Ca,2n) 250 Fm (HgS targets) A. Pritchard, R.-D. Herzberg et al., University of Liverpool
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250 Fm electron spectra
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250 Fm preliminary PT Greenlees, RDH et al, preliminary! JUROGAM Tagged with isomer
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250 Fm Levelscheme PT Greenlees, RDH et al, preliminary! ? ?
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Kinematic moment of inertia J (1) even – even nuclei
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Dynamic moment of inertia J (2) even – even nuclei
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Dynamic moment of inertia even – even nuclei
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250 Fm Dynamic Moment of Inertia J (2) Theory: M. Bender et al., NPA 723 (2003) 354 ♦ Exp
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A Afanasiev, priv comm. 250 Fm Kinematic and Dynamic Moment of Inertia J (1) and J (2)
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A. Afanasiev, PRC 67, 24309, (2002) Kinematic and Dynamic Moments of Inertia J (1) and J (2)
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Odd - proton 251 Md 150, 255 Lr 152
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[521]1/2 - [514]7/2- [633]7/2+
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Electromagnetic Properties Odd-proton orbitals in 251 Md / 255 Lr B(M1)/B(E2) depends on (g K -g R )/Q 0 g K ~ 0.7 Mainly E2 [514] 7-27-2 7 -27 -2 7 +27 +2 [633] 7+27+2 g K ~ 1.3 Mainly M1 1 -21 -2 [521] 1-21-2 a ~ 0.9 : g K ~ -0.55 Mainly E2
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Conversion coefficients Z ≈102
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Prompt γ -ray spectroscopy of 251 Md and 255 Lr 205 Tl( 48 Ca,2n) 251 Md ~ 760 nb (A. Chatillon, Ch. Theisen et al. ) 209 Bi( 48 Ca,2n) 255 Lr ~ 300 nb (S. Ketelhut, P. Greenlees et al.)
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Recoil Tagging γγ coincidences First rotational band in an odd-Z transfermium No signature partner : K=1/2 251 Md
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Dynamical Moments of Inertia J (2) J (2) (hbar 2 MeV -1 ) Rotational Frequency
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251 Md Dynamic Moment of Inertia J (2) Theory: M. Bender et al., NPA 723 (2003) 354
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185 200 HFB + SLy4 M. Bender et al. 300 430 W.S. S. Ćwiok et al. ½-½- 7+27+2 HFB + Gogny H. Goutte, priv. comm. 100 7-27-2 ½-½- ½-½- 7-27-2 7-27-2 7+27+2 7+27+2
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255 Lr – Recoil Tagging 209 Bi( 48 Ca,2n) 255 Lr
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255 Lr – Recoil Decay Tagging
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Comparison 255 Lr – 251 Md
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Odd - neutron 253 No 151
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Confirmed by F.P. Heßberger et al. E.P.J. A 22, 417 (2004) The ground state of 253 No is a neutron 9/2 - [734] state GREAT spectra from 207 Pb( 48 Ca,2n) 253 No γ rays electrons 253 No 1.7 min
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Earlier Gammasphere+FMA experiment 207 Pb( 48 Ca,2n) 253 No – 0.5µb P. Reiter et al. PRL 95, 032501 (2005) 253 N o
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JUROGAM + RITU Recoil-gated γ rays from 207 Pb( 48 Ca,2n) 253 No
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253 N o Exp K=7/2 simulation K=9/2 simulation It is not 7/2+[624] band but 9/2-[734] 253 No
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It is not 7/2+[624] band but 9/2-[734] 253 No
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SACRED + RITU data In-beam conversion electrons from 207 Pb( 48 Ca,2n) 253 No K=7/2 simulation K=9/2 simulation Exp 9/2- [734] Indeed P. Butler et al.
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Dynamic moment of inertia J (2)
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Theory: M. Bender et al., NPA 723 (2003) 354
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PERSPECTIVES Improved sensitivity for in-beam studies: Digital signal processing → Higher counting rate Digital signal processing → Higher counting rate Development of high-intensity beams In-beam gamma - electron concidences for SHE: Combined gamma-ray and electron spectrometer - SAGE
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PERSPECTIVES Improved sensitivity for in-beam studies: Digital signal processing → Higher counting rate Development of high-intensity beams 50 Ti + 208 Pb → 256 Rf + 2n 50 Ti + 208 Pb → 256 Rf + 2n In-beam gamma - electron concidences for SHE: Combined gamma-ray and electron spectrometer - SAGE
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In-beam γ rays from 208 Pb( 50 Ti,2n) 256 Rf – 12nb 700 recoils ↔ 25pnA, 1 week Simulation – a random bit of the 254 No experiment 256 Rf Z = 104
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PERSPECTIVES Improved sensitivity for in-beam studies: Digital signal processing → Higher counting rate Development of high-intensity beams In-beam gamma - electron concidences for SHE: Combined gamma-ray and electron spectrometer - SAGE Combined gamma-ray and electron spectrometer - SAGE
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SAGE UK investment
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SAGE
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Collaborating institutes
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Thank you for your attention !
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Moment of inertia
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