The r-process element abundance with a realistic fission fragment mass distribution S. Chiba, H. Koura, T. Maruyama (JAEA) M. Ohta, S. Tatsuda (Konan University) T. Wada (Kansai University) T. Tachibana (Waseda University) K. Sumiyoshi (Numazu CT) K. Otsuki (MSU) T. Kajino (NAO)

Fission (cycling) in r-process nucleosynthesis Discovery of Ｔｈ and Ｕ in metal poor stars For realistic calculation of r-process nucleosynthesis Is there a termination point?　Where is that? Possibility of SHE generation and discovery of its relics in meteorites Impacts on universality (56≦Z≦75) Impacts on nucleo-cosmochronometers Th/Eu, U/Th, Th/Os,....

S=250 Supply to medium-weight region by fission, which is less sensitive to the physical conditions of r-process sites Continuous flow from the bottom

Nuclear data for r-process network calculation including fission Nuclear mass and β-decay rates KTUY05 (Prog. Theor. Phys. 305（2005 ）113)+ GT2 (this work) β-delayed fission rates：new calculation by Gross Theory-2 (GT-2)：mass and Bf from KTUY05 vs. MS96　(this work) Difference due to fission with or without fission symmetric fission⇔realistic distribution by Konan group (this work)

Regions where fissions take place in terms of KTUY05

Calculation of FFMD (Fission Fragment Mass Distribution) Presented by M. Ohta in ND07 and INPC07, S. Tatsuda P-30 (this symposium) Static effect: PES by 2-center shell model collective coordinates：mass asymmetry, distance between fragments, deformation of fragments yields asymmetryα Dynamic effets：based on multi-dimensional Langevin calculation for U, Sg and Fm ratio of symmetric and asymmetric fission： determined by considering calculated and experimental results for Fm isotopes, especially for 264Fm width of FFMD：determined by considering Langevin calculation FFMD is expressed by 3 Gaussians

FFMD　248Cm, 236U

FFMD　236U, 274U

β-decay rate by Gross Theory

β-delayed fission probability Pf Gross Theory of β-decay (TT,Yamada) β-delayed fission or neutron probability Sβ (E): β-strength function λ: decay const. of β-decay f (-E): Fermi function KTUY mass formula Qβ : β-decay Q-value Sn: neutron sep. energy Bf: fission barrier height δW:shell energy Decay width Γn and Γf Phenom. formula (Kawano, SC,HK) Level density formula (Gilbert-Cameron type) Tachibana 10

Dynamical network calculation Terasawa et al., ApJ 562, 470(2001) Reaction rates　 Thielamann , Caughlan-Fowler, Maleney-Fowler, Fowler-Hoyle, Rauscher, Mohr, Wagoner, Kajino-Boyd, Orito-Kajino-Mathews, Kajino-Fukugita,Ohsaki, NACRE96 Nuclear mass Hilf-Groote-Takahashi (modified) KTUY05 (Prog. Theor. Phys. 305（2005 ）113) β-decay rates Klapdor GT-2 with KTUY05 mass, including 1n emission(2007) ν-induced spallation rate (A(ν,e- xn)A') (x=0, 8) Langanke (5 ≦ Z ≦100) with dumping no fission mode ⇒β-delayed fission, spontanious fission(KTUY05) α-decay (KTUY05 mass) Data on expanding matter of SNeII : numerically read ⇒ exponential model

Exponential model for expanding nuclear matter c.f. General-relativistic hydro-dynamical simulation by Terasawa (ApJ 562, 470(2001))（dots） lower 2 lines : T9 upper 2 lines : density Exponential model Ye=Yp=0.427

Entropy-dependence of r-process abundance

Realisrtic FFMD（left） vs. symmetric FFMD（right）

β-delayed fission probabilities (with Bf of KTUY05)

β-delayed fission probabilities (with Bf of Myers-Swiatecki96)

β-delayed fission probabilities (with Bf of KTUY - 3MeV)

Impact of FFMD on abundance : realistic (left) vs. symmetric(right)

(KTUY-3MeV（left）、MS96（right）)

Isotope (or element) production rates

Concluding remarks We are on a way to construct nuclear data relevant to r-process network calculation So far, we have prepared FFMD (Fission Fragment Mass Distribution) Nuclear mass : KTUY05 β-decay rates : Gross Theory β-delayed fission rates β-delayed neutron emission rates We have carried out r-process dynamical network calculations with β-delayed fission and found Strong model dependence onβ-df rates due to difference in Bf If β-ｄｆ is significant, FFMD has a strong impact on abundance If β-df is significant, universality is influenced The model uncertainty in the fission barrier height is still large (around 3 MeV) to make quantitative conclusions on the effect of fission in the r-process abundance Ultimately, we need (n,f) reaction rates : the statistical model code is ready; we need to refine Bf

β遅延中性子放出、β遅延核分裂 TS-1 TS-2 Tn Tγ Sn Bfi Bfo PES deformation (elongation)

, R : Radius of the spherical compound nucleus Calculation of PES 　Liquid drop model + 2-center shell model 3-dimensional parameter space 　- distance between fragments 　- deformation of fragments 　- mass asymmetry A1 A2 , R : Radius of the spherical compound nucleus

β-df region in terms of KTUY05 208Pb β-stable nuclei 132Sn ・β-df nuclei by KTUY05 model n-drip line 238U 208Pb 132Sn β-stable nuclei ・β-df nuclei by KUTY mass model n-drip line 238U 208Pb 132Sn β-stable nuclei ・β-df nuclei by KUTY mass model n-drip line 238U 208Pb 132Sn β-stable nuclei ・β-df nuclei by KUTY mass model n-drip line 238U 208Pb 132Sn β-stable nuclei ・β-df nuclei by KUTY mass model n-drip line 238U 208Pb 132Sn β-stable nuclei ・β-df nuclei by KUTY mass model n-drip line 238U 208Pb 132Sn β-stable nuclei ・β-df nuclei by KUTY mass model n-drip line

Z分布(S=250)

Z分布(S=400)