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LCP

NECK FRAGMENTATION IN FISSION AND QUASIFISSION OF HEAVY AND SUPERHEAVY NUCLEI V.A. Rubchenya Department of Physics, University of Jyväskylä, Finland V.G. Khlopin Radium Institute, St. Petersburg, Russia September 25, 2008, Kazimerz Dolni. Near scission emission of LCP (or IMF) - NSE. LCP.

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LCP

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  1. NECK FRAGMENTATION IN FISSION AND QUASIFISSION OF HEAVY AND SUPERHEAVY NUCLEIV.A. RubchenyaDepartment of Physics, University of Jyväskylä, FinlandV.G. Khlopin Radium Institute, St. Petersburg, RussiaSeptember 25, 2008, Kazimerz Dolni

  2. Near scission emission of LCP (or IMF) - NSE LCP Fission (ternary fission) HI fusion-fission (165Ho+56Fe(465): PRL 51 (1983) 99) neck F2 F1 Quasifission DNS Deep inelalastic collision τ

  3. Possible mechamisms of NSE: • - LCP evaporation from neck region (hot spot) • Neck Fragmentation (NF) due to the dynamical instability of nuclear matter in the neck region. Double random neck rupture model of NF (V. Rubchenya, Sov. J. Nucl. Phys. 35 (1982) 334)

  4. Estimate of the neck rupture time: Ternary fission probability: Coefficients are different for the specific fission modes: m = SY, SI, SII, SAS

  5. Light charged particle multiplicities in the ternary fission

  6. Initial TNS configuration is defined using the sudden approximation

  7. The final mass and charge LCP distribution is mainly formed in the result of nucleon exchange process in DNS (LF + LCP) (V.Rubchenya, S. Yavshits, ZfP A 329 (1988) 217)

  8. Dynamics of superheavy composite systems Interplay between fusion and quasifission Instability toward the neck fragmentation Nuclear friction in superheavy composite systems 86Kr + 208Pb → 294118 At EKr = 460, 500 and 600 MeV Z2/A = 47.36 (BfLDM = 0); αent = 0,415; (Z2/A)eff= 43.67

  9. 86Kr + 208Pb • Reaction parameters • Fissility parameter = Coulomb energy /2 Surface energy = (Z2 / A)/(Z2/A)cr • Z2/A =47.36 • Effective fissility parameter = Coulomb force / proximity force = (Z1Z2e2/(R1 + R2)2)/4πγRav.c = (Z2/A)eff /(Z2/A)cr • (Z2/A)eff = 43.67 • Mass asymmetry parameter : α = (AT - AP) / (AT + AP), α = 0.415 • Capture barrier : Bcupt = 295 MeV, Qfus = 296.9 MeV • ELAB Ecm Ecomp Eex.p. Eex.ex.p. σ fus ΘLABgraz • 318.4 21.8 66 111 < mb 84.5 • 353.7 56.8 -- -- < mb 66.9 • 600 424.5 127.5 -- -- 31 mb 45.9

  10. V = Vnucl + VCoul

  11. Experimental setup to study 86Kr + Pb reaction

  12. TOP VIEW T3 T7 SIDE VIEW T7 T0; T1;T2; T3 beam PSAC

  13. FLNR

  14. Mass yields (normalised to 100% at 97 < M < 197)

  15. 86Kr + 208Pb , E(86Kr) = 460, 500, 600 MeV

  16. TKE and fragment excitation energy at EKr= 600 MeV (Fu-Fi model: V.R. et al. PRC 58(1998)1587)

  17. The difference between experimental TKE and theoretical values (Fu-Fi model)

  18. Post-scission neutron multiplicities

  19. Multiple-source particle emission model Here ΘRFis a direction of the fragmentation axis CN stands for the composite nucleus NF stands for the neck source FR stands for the fragment sources WCN(ε) and WFR(ε) are evaporation spectra X Z VLCP

  20. Light charged particle emission characteristics Mnpre = 0.0 ± 0.9

  21. 86Kr + 208Pb → 294118 at EKr=(500 – 600) MeV

  22. Next experiment in October, 2008: 238U + 64Ni -> 302120, Z2/A= 47.68

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