Synthesis and Decay Properties of the Heaviest Nuclei in 48 Ca induced Reactions

1. Synthesis and Decay Properties of the Heaviest Nuclei in 48Ca induced Reactions Yuri Oganessian Flerov Laboratory of Nuclear Reactions Joint Institute for Nuclear research XII Nuclear Physics Workshop Marie and Pierre Curie Sept. 21-25, 2005, Kazimierz Dolny, Poland

3. hot fusion cold fusion Yu. Oganesyan.XII Nuclear Physics Workshop Marie and Pierre Curie Kazimierz Dolny Sept. 21-25, 2005

4. what are we expecting to see in the experimentunusual properties of SHE • what we have already observed decay modes of SHE • setting the experiments synthesis of elements 113 and 115 as an example • Chemistry of SHEidentification of atomic numbers of SHE • reactions of the SHE synthesiskey problem • overall picture of SHE nuclear shells and stability of the SHE • - the search for surviving SHE. Prospects

5. Reactions of the synthesis Here there are two questions: What is the fusion probability for 48Ca and actinide nuclei? What is the survival probability of the compound nucleus with Z=114-118 at the excitation energy E*30 MeV?

6. fusion probability Let us consider the fusion of the 48Са and 248Cmoccurred and resulted in the formation of the compound nucleus 296116 with an excitation energy of about 40 MeV Evidently, the dominant decay mode of such a nucleus would be fission into two fragments Accordingly, one could attempt investigating the probability of formation of the compound nucleus by measuring its fission characteristics.

7. CORSET setup position sensitive stop detector x, y, E F1 TOF-start detector TOF-start detector mass resolution – 2 a.m.u Target 238U,244Pu 248Cm beam F2 48Ca angular resolution – 0.30 solid angle – 0.3 sr Yu. Oganesyan.XII Nuclear Physics Workshop Marie and Pierre Curie Kazimierz Dolny Sept. 21-25, 2005

8. beam-like target-like CN CN CN M. Itkis et al., (2002) Fragment Energy and Mass Distributions in Cold and Hot Fusion Reactions

9. Z=116 Potential energy surface cold fusion 0

10. Fusion probability

11. hot fusion

12. Fusion probability Yu. Oganesyan.XII Nuclear Physics Workshop Marie and Pierre Curie Kazimierz Dolny Sept. 21-25, 2005

13. the limit of the exp. sensitivity i=x σxn= Pxn∙ Π (Γn / Γf)I ~ (Γn / Γf)x i=1 (Γn / Γf)I ~ exp [(Bf – Bn) / T] where Bf = BfLD + ΔEShell 0 Survival probability

14. x 400 → Ca5+ technology of the target preparation – 0.3 mg/cm2 Separation of super heavy nuclei and detection of their radioactive decays now: DGFRS isotope enrichment 98-99% S-2 separator (Sarov) isotope production high flux reactors (Oak Ridge, Dimitrovgrad) Natural occurrence of Ca isotopes (in %): 40Ca – 96.94 42Ca – 0.647 43Ca – 0.135 44Ca – 2.086 46Ca – 0.004 48Ca – 0.187

15. 248Cm+48Ca 208Pb+64Ni cold fusion what are we expecting to see in the experiment

16. 245Cf,245Cm+48Ca 245,248Cm+48Ca Theory 207Pb+64Ni 208Pb+64Ni …and Experiment

17. Spectra of α-particles and sum kinetic energies of fission fragments from the decay chains of Z=116 isotopes 286114 288114 287114 289114 283112 284112 285112 α-particles 292116 293116 290116 291116 α-particle energy (MeV) Fission fragments 281110 279110 282112 280110 Total kinetic energy of fission fragments (MeV)

18. 110 CL ≥ 99.9% Calculated and Experimental Log Tα v.s. Qα Relationship for even-even Isotopes with Z = 98 - 104 116 114 112

19. Isotope mass identification obtained by the measurements of the excitation functions for xn-channels

20. Z variation of the target-nuclei Excitation functions Mass variation of the target-nuclei Decay properties what we have already observed Z-even nuclei 10% Number of observed decays Z = 118 3 116 19 114 45 112 52 50%

21. setting the experiments Synthesis of Element 115 in the Reaction: 243Am95 + 48Ca20→ 291-x115 Yu. Oganesyan.XII Nuclear Physics Workshop Marie and Pierre Curie Kazimierz Dolny Sept. 21-25, 2005

22. v (A=48) = 0.11 c q = 16.5+ v (A=288) = 0.017 c q = 6.2+

23. Front detector: sensitive area – 50 cm2 For a-particles e=87% from 4p For SF-fragments e=100%

25. odd-odd a Yu. Oganesyan.XII Nuclear Physics Workshop Marie and Pierre Curie Kazimierz Dolny Sept. 21-25, 2005

26. Actinides Z ≤ 103 Transactinides Z ≥ 104 Nb / Ta / Db - fraction chemistry of the SHE Chemical isolation of 268Db June 2004 ~20 s

27. SF of Z=105 from the Nb/Ta chemical fraction

28. 15 events Spontaneous fission half-life of 268Db (N=163) T1/2 = 30h 268Db 252Cf QF ~ 280 MeV

29. 5 Yu. Oganesyan.XII Nuclear Physics Workshop Marie and Pierre Curie Kazimierz Dolny Sept. 21-25, 2005

30. 2002 2002 - 2004 245Cm+48Ca 242Pu+48Ca 238U+48Ca Synthesis of Element 118 in 249Cf + 48Ca Reaction 2005 29 116

31. overall picture of SHE

32. Alpha-decay energy vs. neutron number For the isotopes of elements with Z >102

34. the search for SHE in Cosmic rays 108 y 105 y 1y 1d Yu. Oganesyan.XII Nuclear Physics Workshop Marie and Pierre Curie Kazimierz Dolny Sept. 21-25, 2005

35. Fréjus peak Entrance to the road tunnel Modane France the search for surviving SHE Search for SF of natural Eka Os by detection of fission neutrons Italy 1 SF-event per year (T1/2=109y) corresponds to the concentration: EkaOs/Os = 5.10-15g/g (or 10-22g/g in the terrestrial matter, or 10-16 of U)

36. Search in Nature Chemical properties(relativistic effect) Astrophysics(search for SHE in cosmic rays) Nucleosynthesis (test of the r-s process) Atomic physics(structure of SH-atoms) Yu. Oganessian. “Synthesis and Decay Properties of the Heaviest Nuclei”. Nilsson-2005, Lund, June 15 2005

37. Flerov Laboratory of Nuclear Reactions of JINR …in February Thanks for your attention