Models for spontaneous fission of heavy nuclei and
nucleosynthesis of cosmo-chronometers in the r-process.
Panov Igor
(ITEP, NGU)
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Introduction
Rapid nucleosynthesis – models and sites
R-process under high neutron environment
Fission in the r-process
(n,f)- and b-delayed fission
fission cycling
lsf – predictions
Theoretical Abundance of heavy nuclei
Superheavy nuclei and cosmochronometers
Conclusion
s-, r- processes
SHE
nucleosynthesis beyond Fe-peak – r-process and
s-process
r-process and s-process paths
supernovae
NSM
winds
J.Truran
Nuclear data for the r-process: ~6000 nuclei are involved
900 nuclei hasT12 > 1 hour
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нуклеосинтез в реакциях с нейтронами (s-процесс):
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108
Z=48
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111
112
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111
129109
110
b
107
Z=47
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109
b
bZ=46 105
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Pd Ag Cd
107
108
ln << lb
nn<1012
нуклеосинтез в реакциях с нейтронами (r-process):
131
Z=49
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133
b
Z=48
130
131
b
Z=47 126
Ag Cd In
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128
ln lb
nn>1022
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129130
Waiting point
131 130
(s-процесс: ln << lb)
nn<1012
2. Main conditions for the r-process:
(seeds); free neutrons; n/seeds; freezout
SnII , r ~ r0 exp(-t/thyd), thyd < 10ms
Merging of close binaries: NSNS, NSBH
high n/seeds > 150, T9< 1, Ye < 0.1
Neutrino-induced r-process 4He(n,n’ n)3He
Explosions on the NS surface
Hot n-wind, high entropy wind
– thermonuclear Sne, jets ?
Other objects and processes?
Wasserburg, G., Busso, M., & Gallino, R. 1996, ApJ, L109
2 objects /scenario: Main r-process - Weak r-process
weak r-process
SNIa
- Truran & Cowan He-flash 1983
- Blinnikov, Panov, Ptytsin, Chechetkin 1995
SNII
neutrino-induced r-process
-Nadyozhin, Panov, Blinnikov A&A, 335, 1998
NSM-model, main r-process?
Freiburghaus et al., AJL 525, 1999
NS+BH
Janka, Wanajo, 20011
Blinnikov, S. I., et al. Pazh, 10,
(1984) 422
Lattimer et al., AJ 213, 225 (1977)
3. R-process under high neutron density environment – in NSM
Observed Nr
fission
Network calculations of the r-process
Z+2
fission
b
Z
(n,)
(,n)
adecay
b
Z2
Pkn (k=0,1,2,3)
A4
A2
A
A+2
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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
4. fission in the r-process and rates calculations
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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,) 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,)
• Petermann Martinec-Pinedo Langanke Panov Thielemann SHE AA2012
• Panov, I.Korneev, Yu. Lutostansky, F.-K. Thielemann. Yad.Fiz. 2013. Pbdi
5.lnf , ln and lb rates comparison
for U (left) and Cm (right)
n, nf, n – Hauser-Feshbach predictions
lb, lbdf, - QRPA
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6. 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
6. 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;
R=∫li(t) / ∑i ∫ li(t)dt
: Bf < Sn; : nuclei with Bf ≥ Sn; inclined crosses: nuclei with
neutron binding energy predicted by the ETFSI Sn ~ 2 MeV; and dots:
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nuclei in which 2 > Sn > 0.
7. 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)
• 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, ln < lb
nn < 1012, ln << lb
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JINR => Zagrebaev et al. Phys. Rev. C 84, 044617 (2011)
Amax(progenitors) ≈280
A(progenitors) ~ < 260
Final abundances YA , tR ~ 0.4 – 4 109 years
Final abundance YA when s.f. rates ~
f(Bf)
Final YA when s.f.rates - macro-micro model
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Conclusions
• It was shown that s.f. model applied to the r•
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process nucleosynthesis strongly influe in first
turn on 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 nucleicosmochronometers, pairs 232/244 or 238/244
can be considered
The detailed investigation of decay chain is
needed
Thank you !
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Participants for attention
• Blinnikov, Dolgov, Korneev, Thielemann
for collaboration
Fission cycling – fission fragments are involved in the
r-process as new seeds
Bf
TF Myers, Swiatecky 1999
Map of nuclei and field of rates
o
- “солнечная” распространенность элементов
синим цветом – расчет для сценария слияния нейтронных звезд в двойной системе
( Панов, Корнеев и Тилеманн.
Письма в АЖ, т.34, 2008;)
Model, SS and metal-poor halo star CS 22892-052