• Introduction Introduction • Fission in the r-process Fission in the r-process • (n,f)- and (n,f)- and -delayed fission-delayed fission• fission cyclingfission cycling• Contribution different fission modesContribution different fission modes• sf sf – predictions – predictions • Superheavy nuclei and cosmochronometersSuperheavy nuclei and cosmochronometers• ConclusionConclusion

Spontaneous fission of heavy nuclei and nucleosynthesis of cosmo-chronometers in the r-

process. Panov Igor

(ITEP)

fission

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

Observed Nr

fissionfission

decaydecay

PPkn (k=0,1,2,3)

Network calculations of the r-processNetwork calculations of the r-process

(n,) (n)

10

Nuclear data for the r-process (up to 6000 nuclei )

• beta-decay,

•Cross-sections and reaction rates (n,g), (n,f), ..

• beta-delayed processes Pin, Pdf

• spontaneous fission, sf

•Mass distribution of fission products•Alpha-decay, •Nuclear masses and fission barriersData base of common usage

JINA - Joint Institute of Nuclear AstrophysicsJINA - Joint Institute of Nuclear Astrophysics

• Seeger, Fowler, et al. (1965) ; Ohnishi (1977) • Thielemann, Metzinger, Klapdor, Zt.Phys., A309 (1983) 301. Pdf=100%• Goriely et al. Astron. Astrophys. 346, 798–804 (1999) s.f. (Swiatecky)• Panov et al., Nucl. Phys. A, 718 (2003) 647. (n,fission) vs Pdf

• I.Korneev et al. NIC-2006; Astronomy Letters, 66 (2008) 131 Yff(Z,A)• Kelic, et al., Phys. Lett. B. 616 (2005) 48 Yff(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,) Pdf

• G.Martinec-Pinedo et al, Progress in Particle and Nuclear Physics, 59 (2007) 199. (n,fission) vs Pdf

• Y.-Z. Qian, Astron. J. 569 (2002), p. L103. induced fission

• Kolbe, Langanke, Fuller. Phys Rev Lett. 2004 induced fission • I. Petermann et. al. NIC-2008; G.Martinec-Pinedo et al, Progr. in Particle

and Nucl. Phys., 59 (2007) 199-205: (n,fission), Pdf , s.f., induced f..• Panov et al. AA 2010Panov et al. AA 2010 (n,fission) and (n,) • Petermann Martinec-Pinedo Langanke Panov Thielemann SHE AA2012• Panov, I.Korneev, Yu. Lutostansky, F.-K. Thielemann. Yad.Fiz. 2013. Pdi

3. fission in the r-process and rates fission in the r-process and rates calculationscalculations

4. Fission cycling during r-process for NSM conditions 4. Fission cycling during r-process for NSM conditions (t-duration time of the r-process; t=0 - initial composition)(t-duration time of the r-process; t=0 - initial composition)

Neutron star mergers modelling: Rosswog et al. 1999R-process: Panov I., Thielemann F.-K. AL, 30 (2004) 711

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

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;

5.

R=∫i(t) / ∑i ∫ i(t)dt

6. Spontaneous fission 6. Spontaneous fission ratesrates

• Lg(sf ) ~ Bf (Frankel&Metropolis,1947) :

Lg(sf ) = 33,3-7,77Bf(exp) (1)

Lg(sf ) =50,127-10,145Bf(etfsi) (2)

Panov, Korneev, G. Martinez-Pinedo, Thielemann, 2013

• LgLg((sf sf ) = ) = --11461146,,4 + 754 + 75,,33ZZ22//A A –– 11,,638(638(ZZ22//AA))22 + + 00,,012(012(ZZ22//AA))33 --(7(7,,24 24 --00,,095095ZZ22//AA))BBf f (3)(3)

Zagrebaev, Karpov 2012 (Zagrebaev, Karpov 2012 (Swiatecki, 1957))

• Macro-micro model, Smolanchuk et al. 1997Macro-micro model, Smolanchuk et al. 1997 (4)

Bf ETFSI- Mamdouh et al., NP 2001

R-process path and abundances YA(Z,N) when duration r ~ 10s

nn < 1022 cm-3, n < Squares – most abundant nucleiWhite dots: 10% < Pdf < 90%

A(progenitors) ~ < 260

25

nn < 1012, n <<

JINR => Zagrebaev et al. Phys. Rev. C 84, 044617 (2011)

Amax(progenitors) ≈280

Final abundance YA when s.f. rates ~

f(Bf)

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

30

ConclusionsConclusions• Spontaneous fission model strongly influe Spontaneous fission model strongly influe

upon the r-process nucleosynthesis upon the r-process nucleosynthesis yields of nuclei-cosmochronometersyields of nuclei-cosmochronometers

• Among tested models of spontaneous fission Among tested models of spontaneous fission phenomenological model based on phenomenological model based on Swiatecki model and on macro-micro model Swiatecki model and on macro-micro model predictions gave the better results in predictions gave the better results in calculation of yields of nuclei–calculation of yields of nuclei–cosmochronometerscosmochronometers

• Additionally to 232/235, 235/238 pairs of Additionally to 232/235, 235/238 pairs of nuclei-cosmochronometers, pairs 232/244 or nuclei-cosmochronometers, pairs 232/244 or 238/244 can be considered238/244 can be considered

• The detailed investigation of decay chain is The detailed investigation of decay chain is neededneeded

Thank youThank you !!

• everybody for attention and everybody for attention and collaborationcollaboration

• SNF for supportSNF for support

Final abundances YFinal abundances YA , R ~ 0.4 – 4 109 years