The role of fission in r-process nucleosynthesis Gabriel Martínez Pinedo INT Program INT13-3: “Quantitative Large Amplitude Shape Dynamics: fission and heavy ion fusion” October 4, 2013 Nuclear Astrophysics Virtual Institute Introduction Fission and the r-process Outline 1 Introduction 2 Fission and the r-process Fission barriers Are super-heavy nuclei produced in the r-process? Shell structure super-heavy nuclei Fission yields Introduction Fission and the r-process Signatures and nucleosynthesis processes Solar system abudances contain signatures of nuclear structure and nuclear stability. They are the result of different nucleosynthesis processes operating in different astrophysical environments and the chemical evolution of the galaxy. 8 4...6 10 y M~10 Mo dense 6 molecular star formation (~3%) H condensation clouds 1010 He 8 10 O C Ne interstellar 106-1010 y 6 Si S Fe medium 10 stars star M > 0.08 M D Ca Ni o s 104 infall dudustst 2 winds 10 Ge Sr SN explosion Ba mixing B Xe Pb SNR's & ~90% 100 Li Pt hot Be r s bubbles r s Galactic compact Abundance relative to Silicon = 10 −2 remnant 10 SNIa (WD, 0 20 40 60 80 100 120 140 160 180 200 220 halo 2 6 Mass Number 10 -10 y NS,BH) Introduction Fission and the r-process Nucleosynthesis beyond iron (Traditional description) Three processes contribute to the nucleosynthesis beyond iron: s-process, r-process and p-process (γ-process). 10 2 80 1 10 s r s ] 0 70 p-drip 6 10 r 10 -1 60 -2 Z 10 50 10 -3 115 Sn 180 p n-drip -4 138 W 40 10 La Abundances [Si=10 152 10 -5 Gd 30 164 180 m Ta 10 -6 Er 40 60 80 100 120 80 100 120 140 160 180 200 N A 10−12 −3 s-process: relatively low neutron densities, nn = 10 cm , τn > τβ 20 −3 r-process: large neutron densities, nn > 10 cm , τn < τβ. p-process: photodissociation of s-process material. Introduction Fission and the r-process Heavy elements and metal-poor stars Cowan & Sneden, Nature 440, 1151 (2006) Stars rich in heavy r-process elements (Z > 50) 0 and poor in iron (r-II stars, [Eu=Fe] > 1:0). ε Robust abundance patter for Z > 52, −2 consistent with solar r-process abundance. −4 These abundances seem the result of events Relative log that do not produce iron. [Qian & Wasserburg, −6 Phys. Rept. 442, 237 (2007)] −8 30 40 50 60 70 80 90 Possible Astrophysical Scenario: Neutron star Atomic Number mergers. 0.5 (b) Sr 0 Zr translated pattern of CS 22892-052 (Sneden et al. 2003) Ru Stars poor in heavy r-process elements but -0.5 Mo Pd -1 with large abundances of light r-process ) Y Z ( elements (Sr, Y, Zr) ε -1.5 Nb log -2 Production of light and heavy r-process Ag elements is decoupled. -2.5 -3 HD 122563 (Honda et al. 2006) Eu Astrophysical scenario: neutrino-driven -3.5 40 50 60 70 80 winds from core-collapse supernova Atomic Number (Z) Honda et al, ApJ 643, 1180 (2006) Introduction Fission and the r-process Astrophysical sites Core-collapse supernova Neutron star mergers Neutrino-winds from protoneutron Matter ejected (∼ 0:01 M ) stars. dynamically during merger. Aspherical explosions, Jets, Electromagnetic emission from the Magnetorotational Supernova, ... decay of r-process nuclei [Kilonova, [Winteler et al, ApJ 750, L22 (2012)] Metzger et al, MNRAS 406, 2650 (2010)] Winds from accretion disks around black holes [Wanajo & Janka, ApJ 746, 180 (2012)] Introduction Fission and the r-process Transients from r-process ejecta Introduction Fission and the r-process Radioactive heating and light curve The r-process heating at late times 1020 −1:3 ) goes like t . −1 56 18 Ni g 10 Fission −1 Beta decay 16 Similar to nuclear waste from 10 Total heating terrestrial reactors. 1014 Independent of the ejecta 1012 composition. 1010 108 Energy generation (erg s Independent of the nuclear mass 10−6 10−5 10−4 10−3 10−2 10−1 100 101 102 103 model. Time (days) 1042 Light curve reaches peak ) brightness at times of 1 day, −1 reaching luminosities 1000 times 1041 those of a typical Nova. Results are sensitive to photon Luminosity (erg s Efficiency = 1.0 Efficiency = 0.5 opacities (Kasen et al, 2013) 1040 0.1 1 10 Metzger, GMP, Darbha, Quataert, Arcones et Time (days) al, MNRAS 406, 2650 (2010) Introduction Fission and the r-process Kilonova Observation LETTER doi:10.1038/nature12505 A ‘kilonova’ associated with the short-duration c-ray burst GRB 130603B N. R. Tanvir1, A. J. Levan2, A. S. Fruchter3, J. Hjorth4, R. A. Hounsell3, K. Wiersema1 & R. L. Tunnicliffe2 Time since GRB 130603B (d) N 1 10 0.6 m I μ 10–11 21 X-ray F606W F 22 F160W 23 –12 T 10 X-ray Dux (er 24 O5″ 25 g s –1 1.6 μm –13 10 cm AB magnitude 26 –2 N ) 27 N 28 F10–14 29 E 104 105 O106 Time since GRBOO 130603B (s) Direct observation of an r-process nucleosynthesis event? Nbur Introduction Fission and the r-process Magnetorotationally Driven Supernovae Winteller et al, ApJ 750, L22 (2012) ] 120 ⊙ M 5 100 − 0 80 [1 ss a 60 M d 40 e t ec 20 j E 0 0.10 0.15 0.20 0.25 0.30 0.35 0.40 Ye 2 10− ] 3 ⊙ 10− [M 4 ss 10− a M 5 d 10− e t ec j 10 6 E − 10 7 − 60 80 100 120 140 160 180 200 220 240 Mass Number Introduction Fission and the r-process Neutron-star mergers: Astrophysically robust Korobkin, Rosswog, Arcones, & Winteler, MNRAS 426, 1940 (2012) 0.5 Yi Ye -4 0.4 10 0.2 -5 0.3 10 0.1 10-6 0.2 0 13 14 10 10 ns1.0-ns1.0 ns1.4-ns1.4 ejecta mass fraction 3 -7 0.1 l [g/cm ] 10 ns1.2-ns1.2 ns1.2-ns1.0 ns1.4-ns1.0 -8 ns1.4-bh5 0 10 ns1.4-bh10 0 0.05 0.1 0.15 0.2 0.25 0.3 120 130 140 150 160 170 180 190 200 210 Ye Mass number A Introduction Fission and the r-process Sensitive to nuclear physics input 10−3 10−4 10−5 10−6 Abundance Solar r−process Abundances FRDM −7 WS3 10 HFB 21 DZ31 10−8 100 120 140 160 180 200 Mass Number Bauswein, Goriely, Janka, ApJ 773, 78 (2013) Joel Mendoza-Temis (PhD) Strong sensitivity nuclear physics input and particularly fission. Introduction Fission and the r-process Nuclear physics needs Fission rates and distributions: • n-induced • spontaneous E-delayed n-emission • E-delayed branchings (final abundances) E-decay half-lives (abundance and process speed) n-capture rates • for A>130 in slow freezeout • for A<130 maybe in a “weak” r-process ? Q-physics ? Seed production rates (DDD,DDn, D2n, ..) Masses (Sn) (location of the path) figure from H. Schatz Introduction Fission and the r-process Fission input in the r-process R-process simulations require rates for neutron capture, beta-decay (including delayed neutron emission) and alpha-decay. Whenever fission becomes important we also need fission rates and yields (including neutrons produced) for the following fission induced reactions: Neutron induced fission Beta-delayed fission Spontaneous fission Gamma induced fission(?) Neutrino induced fission(?) Introduction Fission and the r-process Fission relevance for the r-process In my opinion these are the questions we need to address: Where in the (Z; N) plane does fission occur at the different phases of the r-process? Does fission constitute a barrier to the production of heavier nuclei or just a “mine field” that can be partly crossed? What are the fission yields produced by the fissioning nuclei? Are there new magic neutron numbers above N = 126? If so, what is their strength? Can long live superheavy nuclei be produced in the r-process? Introduction Fission and the r-process Nuclear Landscape Erler et al., Nature 486, 509 (2012) 120 Stable nuclei line Known nuclei drip Drip line oton Two-pr N = 258 S Z on drip line 2n = 2 MeV = 82 Z 80 , wo-neutr SV-min T N = 184 110 Z = 50 oton number Pr 40 N = 126 100 Z = 28 Z N = 82 = 20 90 230 244 N 232 240 248 256 N = 28 = 50 N = 20 0 0 40 80 120 160 200 240 280 Neutron number, N Petermann et al., Eur. Phys. J. A 48, 122 (2012) ! # *+,- ./012 α # # 2342.56207/889-:0;<0-*+, − − '# β β ) ' 0=>/47?.2@ &# %# % $# $ ## # ! " # $ % & ' ! " ( The r-process explores the limits of stability. Fission Barrier Calculations for the r-process nuclei Full symbols – experimental data Lines – calculations (LDM,TF, ETFSI) A. Mamdouh et al. NPA679 (2001), 337 Po ETFSI U ETFSI [MeV] TF f B TF LDM LDM Slide from A.Andreyev Slide from Neutron Number Neutron Number • Good agreement between Bf,cal and Bf,exp for nuclei close to stability • Large disagreement far of stability (both on n-def. and n-rich sides)1 • Need measured fission data far of stability to ‘tune’ fission models Introduction Fission and the r-process Evolution fission rates 100 0 2 102 10 Beta delayed fission 10 Beta delayed fission 1 101 Neutron induced fission 10 10−1 Neutron induced fission −1 10 Spontaneous fission 100 Spontaneous fission 100 n/seed n/seed −1 −2 −1 −2 10 10 10 ) 10 ) −2 −1 −2 10 d −1 s 10 d s ee −3 ( −3 −3 s ee ( e 10 10 10 −3 / t s e 10 / t n a n a −4 −4 R 10 R 10 −4 10−4 10 −5 10−5 10 −6 −6 10 −5 10 10−5 10 −7 10−7 10 −6 −8 10−6 10−8 10 10 0.1 1 10 100 0.1 1 10 100 Time (s) Time (s) 0 10 0 2 2 10 10 10 Beta delayed fission Beta delayed fission 1 101 10 10−1 Neutron induced fission −1 Neutron induced fission 10 Spontaneous fission 100 Spontaneous fission 100 n/seed n/seed −1 −2 −1 −2 10 10 10 ) 10 ) −2 −1 −2 10 d −1 s 10 d s ee −3 ( −3 −3 ee ( s 10 −3 e 10 10 / t s e 10 / t n a n a −4 −4 R 10 R 10 −4 10−4 10 −5 10−5 10 −6 −6 10 −5 10 10−5 10 −7 10−7 10 −6 −8 10−6 10−8 10 10 0.1 1 10 100 0.1 1 10 100 Time (s) Time (s) Fig.