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IMPULSE
NUCLEOSYNTHESIS
Yu.S. Lutostansky, V.I. Lyashuk, and I.V. Panov
National Research Center "Kurchatov Institute"
Institute of Nuclear Research RAS
Institute of Theoretical and Experimental Physics
ITEP – 10.09.2013
PROCESSES OF NUCLEOSYNTESIS.
Superheavy
nuclei
β-decay
s-process track
β-decay
r-process track
The tracks of elements synthesis in s (slow)- and r (rapid)- processes.
fission
NUCLEOSYNTHESIS OF THE HEAVY NUCLEI
Dynamic r-process
NUCLEOSYNTHESIS OF THE HEAVY NUCLEI in s (slow) and r (rapid)- processes
– nuclei withT1/2 1 y. ; О – T1/2 < 1 y.; + - predictions.
Dynamic r-process track.
r –process equations for the concentration calculations.
Dynamic model: n/ n(A, Z)→ n/ n (A, Z, t); n(A, Z) → n(A, Z, t)
Concentrations n(A,Z, t) are changing in time (may be more than 4000 equations):
dn(A, Z, t)/dt = – (A, Z).n(A, Z, t) – n(A, Z, t).n(A, Z, t) +
+ n(A+1, Z, t).n(A+1, Z, t) + n(A–1, Z, t).n(A–1, Z, t) – n(A, Z).n(A, Z, t) +
+ (A, Z–1).n(A, Z–1, t) × P(A, Z–1) + (A+1,Z–1).n(A+1,Z–1,t) × P1n(A+1,Z–1)+
+ (A+2,Z–1).n(A+2, Z–1, t)×P2n(A+2,Z–1) + (A+3,Z–1)n(A+3, Z–1, t) × P3n(A+3,Z–1)+
+ Ff (A, Z) + (A, Z, t)
n(t) and n(t) – rates of (n,γ) and (γ,n) –reactions; all fluxes and spectra are time depended
=ln(2/T1/2) — -decay rate,
P - probability of (A, Z) nuclide creation after –-decay of (A,Z-1) nuclide. Branching coefficients of
isobaric chains - P1n, P2n, Р3n corresponds to probabilities of one-, two- and three- neutrons emission in
–- decay of the neutron-rich nuclei.
Ff (A, Z) describes fission processes — spontaneous and beta-delayed fission.
(A, Z)
- neutrino capturing processes.
MODEL DESCRIPTION OF Sβ(E) – 2. T1/2 calculations 1988.
Time of new nuclei synthesis
β-decay time:
Q
T
1
1/ 2
S
(i )
i
( E ) f ( Z , Q E ) dE
0
Fermi-function:
E
f F ( Z , U )U
U
2
1 ( E U ) S L (U ) dU
2
1
The dependence of r-process duration time on mass A-value under different external conditions:
curve 1) – constant nn=1026 cm-3, T=1.5 109K; 2) – the same nn, T=1.109K; 3) – dynamical calc.
with ρ0=2.105 g/cm5, T=1.109K [(t) = 0 . ехp (-t/H), Т(t)= Т0 . ехр(-t/3H)].
Yu.S. Lutostansky, and I. V. Panov. Astron. Letters. 14, no 2 (1988) 168.
DYNAMIC MODEL OF NUCLEOSYNTHESIS
Yelds of Nuclei,
calculated in static
(curve 2) and
dynamic pulse r –
processes
(curves 3 and 4).
Numbers denote:
1- exp abundance
data.
Curves 2 and 3
- Calculations with
different parameters.
Curve 2: nn=1024 сm-3,
Т9=109K, н=;
Curve 3:
0 = 2105 gсm-3,
Т9=2x109K, н=1 s.
Curve 4 (doted line) –
calculations with
solar abundance
initial nuclei
concentration of
s – elements.
Lyutostansky Yu.S., Malevanny S.V.,
Panov I.V., Chechetkin V.M. Canada 1987
Yields (concentrations in relative units) for “Par” and “Barbel” experiments
Yields of
transuranium
nuclei measured in
the thermonuclear
explosions “Par”
and “Barbel”
(LANL data).
Red line –
approximation
Y = exp(–1.442A +
+ 354.56)
2
“ПАР” Фн ~ 7х1024 н/см
24
“Par” Фn ~ 7х10 n/cm2
“Barbel”
“Барбел”
Ю.С. Лютостанский,
Odd-Even inversion
effect В.И.
Ляшук,
И.В. Панов. Известия АН СССР
Сер. Физ. 1990, т. 54, стр. 2137;
Препринт ИТЭФ 25-90, М. 1990.
Prompt process in the explosive nucleosynthesis
Multiple neutron capturing process on Uranium material (U – target) , t < 10-6 s.
r(rapid) – process in the explosive nucleosynthesis
–
The initial concentration changed because of β-delayed fission and neutron
emission during cooling processes (return to the value of β-stability).
Factor of the concentration losing in Prompt-process
Np β-delayed fission
probabilities
NUCLEOSINTHESIS AFTER NEUTRON PULSE – 1
Схема образования актинидов в быстром (r-процесс) нуклеосинтезе (ядерный взрыв); –
ядра с T1/2 1 г ; О – ядра с T1/2 < 1 г; + - прогнозируемые нейтронно-избыточные ядра
NUCLEOSINTHESIS AFTER NEUTRON PULSE – 2
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