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Reactions with exotic nuclei ( at FLNR )

Reactions with exotic nuclei ( at FLNR ). Recent experiments on fusion of 6 He Deep sub-barrier fusion of neutron rich nuclei A few words about astrophysics. 6 He. D ubna R adioactive I on B eam s. 400-cm cyclotron radioactive ion beams. low energy beam line. ISOL.

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Reactions with exotic nuclei ( at FLNR )

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  1. Reactions with exotic nuclei( at FLNR ) • Recent experiments on fusion of 6He • Deep sub-barrier fusion of neutron rich nuclei • A few words about astrophysics

  2. 6He Dubna Radioactive Ion Beams 400-cm cyclotron radioactive ion beams low energy beam line ISOL Electron accelerator Acculinna DIRECT 400-cm cyclotron DIRECT 7Li

  3. Fusion, transfer and breakup reaction mechanisms induced by halo nucleus 6He JINR (Dubna), CSNSM (Orsay), IRS (Strasbourg), ULB (Bruxelles), Vanderbilt Univ. (USA) 166Er(6He,6n)166Yb & 165Ho(6Li,5n)166Yb <==> 166Er(4He,4n)166Yb//PRC48(1993)319// 3 2 1 6He + 166Er 172Yb* 166Yb + 6n 6He + 166Er 170Yb* + 2n 6He + 166Er 168Er* + 4He DRIBs Dec.- January’07 U400

  4. Complete & incomplete fusion reactions with 6He (E=62 MeV) 6He + 166Er →172Yb* →166Yb + 6n →167Yb + 5n →170Yb*+2n → 168Yb + 4n → 168Er* + α → 168Er

  5. Data analysis using EMPIRE-II code http://www.nndc.bnl.gov/nndcscr/model-codes/empire-ii/ The statistical model used in the EMPIRE-II is an advanced implementation of the Hauser-Feshbach theory. The exact angular momentum and parity coupling is observed. The emission of neutrons, protons alpha-particles and light ion is taken into account along with the competing fission channel. The full gamma-cascade in the residual nuclei is considered.

  6. EMPIER-II calculation of sxn and sfus 5n 4n 6n 5n 6n 4n B(6He+Er) = 16 MeV, B(6Li+Ho) = 26 MeV

  7. At well-above barrier energies there is no difference between 6He and 6Li from the point of view of the fusion probability. Other reaction channels are still under analysis.

  8. Sub-barrier fusion of 6He M.S. Hussein, M.P. Pato, L.F. Canto and R. Donangelo,Phys.Rev. C 46, 377 (1992). L. F. Canto, R. Donangelo, P. Lotti and M.S. Hussein,Phys.Rev. C 52, R2848 (1995). N. Takigawa and H. Sagawa, Phys.Lett. B 265, 23(1991). C.H. Dasso and A. Vitturi, Phys.Rev. C 50, R12 (1994). K. Hagino, A. Vitturi, C.H. Dasso and S.M. Lenzi,Phys.Rev. C 61, 037602 (2000). A.S. Fomichev et al., Z.Phys. A 351, 129 (1995). J.J. Kolata et al., Phys.Rev.Lett. 81, 4580 (1998). M. Trotta, J.L. Sida, N. Alamanos et al., Phys.Rev.Lett.84, 2342 (2000). R. Raabe, J.L. Sida, J.L. Charvet et al., Nature 431, 823(2004). A. Di Pietro et al., Phys. Rev. C 69, 044613 (2004). A. Navin et al., Phys. Rev. C 70, 044601 (2004). C. Beck, N. Keeley, and A. Diaz-Torres, Phys. Rev. C 75, 054605 (2007). …

  9. Neutron excess itself does not play an important role Neutron transfer with positive Q-value is important !

  10. Sub-barrier fusion enhancement due to neutron transfer( sequential fusion, “energy lift” )

  11. Time dependent Schrödinger equation( Zagrebaev, Samarin & Greiner, PRC 2006) Wave functions of valence neutrons spread over both nuclei before they reach and overcome the Coulomb barrier

  12. Proposed experiments

  13. First experiment

  14. SETUP FOR ACTIVATION MEASUREMENTS with MSP-144 dE/dx~40keV/mm target~20mm E ~ 0.4MeV

  15. Huge enhancement in deep sub-barrier fusion of weakly bound nuclei

  16. Fusion of light neutron rich and stable nuclei

  17. Light neutron rich nuclei in astrophysical nucleosynthesis ?

  18. in particular, instead of the bottle-neck three-body reaction 4He + 4He (→8Be, 10-16s ) + 4He → 12C, 4He + 6He(1s) → 9Be + n probably may occur.

  19. Fusion of light neutron rich nuclei produced in the r-process may significantly change the nucleosynthesis scenario ?

  20. Experiments which could be performed • 1H(9Li,nγ)9Be • 3He(9Li,2nγ)10B • 6Li(9Li,2nγ)13C • 9Be(9Li,2nγ)16N • 10B(9Li,3nγ)16O • 12C(9Li,2nγ)19F • 14N(9Li,2nγ)21Ne • … • 1H(6He,nγ)6Li • 3He(6He,2nγ)7Be • 6Li(6He,nγ)11B • 9Be(6He,2nγ)13C • 10B(6He,2nγ)14N • 12C(6He,2nγ)16O • 14N(6He,2nγ)18F • …

  21. Reactions with6He

  22. Reactions with с 9Li

  23. Standard scenario for nucleosynthesis

  24. Уровни 7Liи 9Be

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