Transcript Влияние массового распределения осколк

Spontaneous fission of heavy nuclei and
nucleosynthesis of cosmo-chronometers in the rprocess.
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. R-process under high neutron density environment – in NSM
Observed Nr
fission
Network calculations of the r-process
Z+2
fission
bZ
(n,g)
(g,n)
a-decay
b-
Z-2
Pkn (k=0,1,2,3)
A-4
A-2
A
A+2
10
Nuclear data for the r-process
(up to 6000 nuclei )
• 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
Data base of common usage
JINA - Joint Institute of Nuclear Astrophysics
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) vs Pbdf
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,g) Pbdf
• G.Martinec-Pinedo et al, Progress in Particle and Nuclear Physics, 59 (2007)
199.
(n,fission) vs Pbdf
• Y.-Z. Qian, Astron. J. 569 (2002), p. L103.
n-induced fission
• Kolbe, Langanke, Fuller. Phys Rev Lett. 2004
n-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), Pbdf , s.f., n-induced f.
• Panov et al. AA 2010
(n,fission) and (n,g)
• Petermann Martinec-Pinedo Langanke Panov Thielemann SHE AA2012
• Panov, I.Korneev, Yu. Lutostansky, F.-K. Thielemann. Yad.Fiz. 2013. Pbdi
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
4. Fission cycling – fission fragments are involved in the
r-process as new seeds
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;
R=∫li(t) / ∑i ∫ li(t)dt
6. Spontaneous fission rates
• Lg(lsf ) ~ Bf (Frankel&Metropolis,1947) :
Lg(lsf ) = 33,3-7,77Bf(exp)
Lg(lsf ) =50,127-10,145Bf(etfsi)
(1)
(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)
Bf
ETFSI- Mamdouh et al., NP 2001
R-process path and abundances YA(Z,N) when duration tr ~ 10s
Squares – most abundant nuclei
White dots: 10% < Pbdf < 90%
nn < 1022 cm-3, lng < lb
A(progenitors) ~ < 260
nn < 1012, lng << lb
25
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
Conclusions
• Spontaneous fission model strongly influe upon
•
•
•
the r-process nucleosynthesis yields of nucleicosmochronometers
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 nucleicosmochronometers, pairs 232/244 or 238/244
can be considered
The detailed investigation of decay chain is
needed
Thank you !
• everybody for attention and collaboration
•
SNF for support
Final abundances YA , tR ~ 0.4 – 4 109 years