1. 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

2. 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

3. 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

4. Recoil – Decay –Tagging (RDT) method

5. 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

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

7. 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

8. 254 No Z = 102, N = 152

9. 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

10. In-beam γγ coincidences from 254 No 254 No ?

11. 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

12. 254 No Levelscheme Long isomer Short isomer 3+ 8- (16+) 55 s R.-D. Herzberg et al. Nature 442, 896-899 (24 August 2006)

13. 250 Fm Z = 100, N = 150

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

15. 250 Fm electron spectra

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

17. 250 Fm 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. 250 Fm Dynamic Moment of Inertia J (2) Theory: M. Bender et al., NPA 723 (2003) 354 ♦ Exp

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

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

24. Odd - proton 251 Md 150, 255 Lr 152

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

26. 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

27. Conversion coefficients Z ≈102

28. 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.)

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

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

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

32. 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

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

34. 255 Lr – Recoil Decay Tagging

35. Comparison 255 Lr – 251 Md

36. Odd - neutron 253 No 151

38. 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

39. Earlier Gammasphere+FMA experiment 207 Pb( 48 Ca,2n) 253 No – 0.5µb P. Reiter et al. PRL 95, 032501 (2005) 253 N o

40. JUROGAM + RITU Recoil-gated γ rays from 207 Pb( 48 Ca,2n) 253 No

41. 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

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

43. 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.

44. Dynamic moment of inertia J (2)

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

46. 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

47. 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

48. 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

49. 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

50. SAGE UK investment

51. SAGE

52. Collaborating institutes

53. Thank you for your attention !

55. Moment of inertia