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Introduction Fission in the r-process ( n,f )- and b -delayed fission fission cycling

Spontaneous fission of heavy nuclei and nucleosynthesis of cosmo-chronometers in the r-process. Panov Igor ( ITEP ). Introduction Fission in the r-process ( n,f )- and b -delayed fission fission cycling Contribution different fission modes l sf – predictions

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Introduction Fission in the r-process ( n,f )- and b -delayed fission fission cycling

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  1. Spontaneous fission of heavy nuclei and nucleosynthesis of cosmo-chronometers in the r-process. Panov Igor (ITEP) • Introduction • Fission in the r-process • (n,f)- and b-delayed fission • fission cycling • Contribution different fission modes • lsf– predictions • Superheavy nuclei and cosmochronometers • Conclusion

  2. 2. R-process under high neutron density environment – in NSM Observed Nr fission

  3. Network calculations of the r-process Z+2 fission b- Z (n,g) (g,n) a-decay b- Z-2 Pkn (k=0,1,2,3) A-4 A-2 A A+2 10

  4. beta-decay, lb Cross-sections and reaction rates (n,g), (n,f), .. beta-delayed processes Pin, Pbdf spontaneous fission, lsf Mass distribution of fission products Alpha-decay, Nuclear masses and fission barriers Nuclear data for the r-process(up to 6000 nuclei ) Data base of common usage JINA - Joint Institute of Nuclear Astrophysics

  5. 3. fission in the r-process and rates calculations • Seeger, Fowler, et al. (1965) ; Ohnishi (1977) • Thielemann, Metzinger, Klapdor, Zt.Phys., A309(1983) 301.Pbdf=100% • Goriely et al. Astron. Astrophys. 346, 798–804 (1999)s.f. (Swiatecky) • Panov et al., Nucl. Phys. A, 718 (2003) 647. (n,fission) vsPbdf • I.Korneev et al. NIC-2006; Astronomy Letters, 66 (2008) 131 Yff(Z,A) • Kelic, et al., Phys. Lett. B. 616 (2005) 48Yff(Z,A) • I.V. Panov, E. Kolbe, F.-K. Thielemann, T. Rauscher, B. Pfeiffer, K.-L. Kratz. NP A 747 (2005) 633 (n,fission) (n,g) Pbdf • G.Martinec-Pinedo et al, Progress in Particle and Nuclear Physics, 59 (2007) 199. (n,fission) vsPbdf • Y.-Z. Qian, Astron. J. 569 (2002), p. L103.n-induced fission • Kolbe, Langanke, Fuller.PhysRevLett. 2004n-induced fission • I. Petermann et. al. NIC-2008; G.Martinec-Pinedo et al, Progr.inParticleandNucl.Phys.,59(2007) 199-205:(n,fission), Pbdf, s.f., n-induced f. • Panov et al. AA 2010(n,fission) and (n,g) • PetermannMartinec-PinedoLangankePanovThielemannSHE AA2012 • Panov,I.Korneev, Yu. Lutostansky, F.-K. Thielemann. Yad.Fiz. 2013. Pbdi

  6. 4. Fission cycling during r-process for NSM conditions (t-duration time of the r-process; t=0 - initial composition) Neutron star mergers modelling: Rosswog et al. 1999 R-process: Panov I., Thielemann F.-K. AL, 30 (2004) 711

  7. 4. Fission cycling – fission fragments are involved in the r-process as new seeds

  8. 5. I.Petermann, A.Arcones, A.Keli´c, K.Langanke, G.Martínez-Pinedo, W.Schmidt, K-H.Hix, I. Panov, T. Rauscher, F.-K. Thielemann, N.Zinner, NIC-2008;

  9. R=∫li(t) / ∑i ∫li(t)dt

  10. 6. Spontaneous fission rates • Lg(lsf )~ Bf(Frankel&Metropolis,1947) : Lg(lsf ) =33,3-7,77Bf(exp) (1) Lg(lsf )=50,127-10,145Bf(etfsi) (2) Panov, Korneev, G. Martinez-Pinedo, Thielemann, 2013 • Lg(lsf ) = -1146,4 + 75,3Z2/A –1,638(Z2/A)2+ 0,012(Z2/A)3-(7,24 -0,095Z2/A)Bf (3) Zagrebaev, Karpov 2012 (Swiatecki, 1957) • Macro-micro model, Smolanchuk et al. 1997(4)

  11. BfETFSI- Mamdouh et al., NP 2001

  12. R-process path and abundancesYA(Z,N) when duration tr ~ 10s

  13. Squares – most abundant nuclei White dots:10% < Pbdf < 90% nn < 1022 cm-3, lng < lb

  14. A(progenitors) ~ < 260

  15. nn < 1012, lng << lb 25

  16. JINR => Zagrebaev et al. Phys. Rev. C 84, 044617 (2011) Amax(progenitors) ≈280

  17. Final abundance YA when s.f. rates ~ f(Bf)

  18. Final YA when s.f.rates - macro-micro model 30

  19. Conclusions • Spontaneous fission model strongly influe upon the r-process nucleosynthesis yields of nuclei-cosmochronometers • Among tested models of spontaneous fission phenomenological model based on Swiatecki model and on macro-micro model predictions gave the better results in calculation of yields of nuclei–cosmochronometers • Additionally to 232/235, 235/238 pairs of nuclei-cosmochronometers, pairs 232/244 or 238/244 can be considered • The detailed investigation of decay chain is needed

  20. Thank you! • everybody for attention and collaboration • SNF for support

  21. Final abundances YA , tR~ 0.4 – 4 109 years

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