1 / 57

Saclay, 30 January 2007 Rauno Julin Department of Physics University of Jyväskylä Finland JYFL

In-beam Spectroscopy of Transfermium Nuclei. Saclay, 30 January 2007 Rauno Julin Department of Physics University of Jyväskylä Finland JYFL. Outline: Introduction Even-Even 254 No ( Z =102, N = 152 ) 250 Fm ( Z =100, N = 150 ) Odd-Proton 251 Md (Z = 101, N = 150)

chiara
Download Presentation

Saclay, 30 January 2007 Rauno Julin Department of Physics University of Jyväskylä Finland JYFL

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. In-beam Spectroscopy of Transfermium Nuclei Saclay, 30 January 2007 Rauno Julin Department of Physics University of Jyväskylä Finland JYFL

  2. Outline: • Introduction • Even-Even • 254No ( Z =102, N = 152 ) • 250Fm ( Z =100, N = 150 ) • Odd-Proton • 251Md (Z = 101, N = 150) • 255Lr (Z = 103, N = 152) • Odd-Neutron • 253No (Z = 102, N = 151) • Future plans

  3. Spectroscopy of very neutron deficient • and heavy nuclei at JYFL •  Can be produced via fusion evaporation with stable-ion beams and stable targets •  Short-living alpha or proton emitters → tagging methods •  Cross-sections down to 1 nb •  Only levels near the yrast line populated

  4. Recoil – Decay –Tagging (RDT) method

  5. RDT Instrumentation at JYFL JUROGAM 43 Ge + BGO Eff. 4% GREAT Focal plane spectrometer RITU Gas-filled recoil separator Transmission 20-50 % TDR Total Data Readout Triggerless data acquisition system with 10 ns time stamping + GRAIN the Analyser

  6. SACRED electron spectrometer at the RITU target prompt e-

  7. Transfermium Nuclei • Produced in asymmetric cold-fusion reaction – X(48Ca,2n)Y • → ideal for the gas-filled separator RITU • → Only one reaction channel open • → Total compound cross-section down to 50 mb • → Ibeam up to 30pnA on a 0.5mg/cm2 target in in-beam runs • Fission dominates: 100000 : 1 • → Ibeam limited by the Ge rate • → Very low focal-plane rate • → Enables long t1/2 – α – tagging

  8. 254No Z = 102, N = 152

  9. 254No In-beam γ- rays from 208Pb(48Ca,2n) 254No - 2µb JUROGAM + RITU 943 842 S. Eeckhaudt et al. EPJ A26, (2005), 227

  10. In-beam γγcoincidences from254No 254No ?

  11. 254No SACRED + RITU data 254No-recoilgated in-beam conversion electrons from 208Pb(48Ca,2n) 254No Discrete lines + M1 continuum M1 P.A. Butler at al. PRL 89 (2002) 202501

  12. 254No Levelscheme R.-D. Herzberg et al. Nature442, 896-899 (24 August 2006) Short isomer (16+) Long isomer 8- 3+ 55 s

  13. 250Fm Z = 100, N = 150

  14. Singles Gamma-Ray Spectra from 204Hg(48Ca,2n)250Fm(HgS targets) A. Pritchard, R.-D. Herzberg et al., University of Liverpool

  15. 250Fm electron spectra

  16. 250Fm preliminary JUROGAM Tagged with isomer PT Greenlees, RDH et al, preliminary!

  17. ? ? 250Fm Levelscheme PT Greenlees, RDH et al, preliminary!

  18. Kinematic moment of inertia J(1) even – even nuclei

  19. Dynamic moment of inertia J(2) even – even nuclei

  20. Dynamic moment of inertia even – even nuclei

  21. 250Fm Dynamic Moment of Inertia J(2) Theory: M. Bender et al., NPA 723 (2003) 354 ♦ Exp

  22. 250Fm Kinematic and Dynamic Moment of Inertia J(1) and J(2) A Afanasiev, priv comm.

  23. Kinematic and Dynamic Moments of Inertia J(1) and J(2) A. Afanasiev, PRC 67, 24309, (2002)

  24. Odd - proton 251Md150 , 255Lr152

  25. [514]7/2- [521]1/2- [633]7/2+

  26. gK ~ 0.7Mainly E2 7+2 [633] 7-2 [514] 7+ 2 7- 2 gK~1.3 MainlyM1 1-2 [521] Mainly E2 a ~ 0.9: gK ~ -0.55 1- 2 Electromagnetic Properties • Odd-proton orbitals in 251Md / 255Lr • B(M1)/B(E2) depends on (gK-gR)/Q0

  27. Conversion coefficients Z ≈102

  28. Prompt γ-ray spectroscopy of 251Md and 255Lr • 205Tl(48Ca,2n)251Md •  ~ 760 nb • (A. Chatillon, Ch. Theisen et al. ) • 209Bi(48Ca,2n)255Lr • ~ 300 nb (S. Ketelhut, P. Greenlees et al.)

  29. 251Md No signature partner : K=1/2 γγ coincidences Recoil Tagging First rotational band in an odd-Z transfermium

  30. Dynamical Moments of Inertia J(2) J (2) (hbar2MeV-1) Rotational Frequency

  31. 251Md Dynamic Moment of Inertia J(2) Theory: M. Bender et al., NPA 723 (2003) 354

  32. 7+2 7-2 7-2 7-2 7+2 7+2 430 300 200 185 100 ½- ½- ½- W.S. S. Ćwiok et al. HFB + Gogny H. Goutte, priv. comm. HFB + SLy4 M. Bender et al.

  33. 255Lr – Recoil Tagging 209Bi(48Ca,2n)255Lr

  34. 255Lr – Recoil Decay Tagging

  35. Comparison 255Lr – 251Md

  36. Odd - neutron 253No151

  37. 253No The ground state of 253No is a neutron 9/2- [734] state GREAT spectra from 207Pb(48Ca,2n)253No 1.7 min γ rays electrons Confirmed by F.P. Heßberger et al. E.P.J. A 22, 417 (2004)

  38. EarlierGammasphere+FMA experiment207Pb(48Ca,2n)253No – 0.5µbP. Reiter et al. PRL 95, 032501 (2005) 253No

  39. JUROGAM + RITU Recoil-gated γrays from 207Pb(48Ca,2n)253No 253No

  40. Exp 253No It is not 7/2+[624] band but 9/2-[734] K=7/2 simulation K=9/2 simulation 253No

  41. It is not 7/2+[624] band but 9/2-[734] 253No

  42. 253No SACRED + RITU data In-beam conversion electrons from 207Pb(48Ca,2n) 253No Exp 9/2- [734] Indeed K=9/2 simulation P. Butler et al. K=7/2 simulation

  43. Dynamic moment of inertia J(2)

  44. Theory: M. Bender et al., NPA 723 (2003) 354

  45. 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

  46. PERSPECTIVES • Improved sensitivity for in-beam studies: • Digital signal processing → Higher counting rate • Development of high-intensity beams • 50Ti + 208Pb → 256Rf + 2n • In-beam gamma - electron concidences for SHE: • Combined gamma-ray and electron spectrometer - SAGE

  47. In-beam γ rays from 208Pb(50Ti,2n)256Rf – 12nb 700 recoils ↔ 25pnA, 1 week Simulation – a random bit of the 254No experiment 256Rf Z = 104

  48. 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

  49. SAGE UK investment

More Related