Stable isotope anomalies and early Solar System chronology

1. Stable isotope anomalies and early Solar System chronology F. Albarède, M. Arnould, R. Carlson, N. Dauphas, T. Fujii, S.Jacobsen, Q. Yin, E. Young

2. Assumption of mass-dependent fractionation of stable isotopes Chronometry must also separate radiogenic ingrowth from isotopic anomalies: • Nucleosynthetic anomalies • Spallation • Mass-independent fractionation Consistent with Urey-Bigeleisen-Mayer (1947) equilibrium fractionation theory and kinetic effects. Additional distillation (Rayleigh) effects permitted.

3. Interpreting isotopic anomalies:evidence of mixing Internally normalized Stable isotopes Trinquier et al. (2006) Luck et al. (2003)

4. Interpreting isotopic anomalies Zanda et al. (2006)

5. I Nucleosynthetic anomalies

6. neutron closed-shell N = 50

7. neutron closed-shell N = 82

8. Predominance domains of the different nucleosynthetic processes Arnould and Gariely (2003)

9. Detecting s- and r-process anomalies on Ba s-process at steady-state: N mirrors s temp (keV) neutron cross-section s in mb (Bao et al., 2000), temperature T in keV

10. Dip of neutron cross-sections forclosed-shells (magic numbers) 138Ba 88Sr 142Nd 90Zr 208Pb

11. Ba nucleosynthetic anomalies Andreasen and Sharma (2007) Ranen and Jacobsen (2007) Carlson et al. (2007)

12. Mass balance equation for nucleosynthetic components f: weight fraction of each component d: deviation from terrestrial abundances Linearity also holds for isotopic ratios of a same element not for different elements

13. Binary (s,r) mixing in Ba from carbonaceous chondrites Andreasen and Sharma (2007)

14. More than two components in Ba from carbonaceous chondrites (p,s,r) Andreasen and Sharma (2007)

15. Binary mixing in Sm … Carlson et al. (2007)

16. … or not?

17. Binary mixing of Mo-Ru nucleosynthetic components Dauphas (2004)

18. Binary mixing of s- and r-process Os components Humayun and Brandon (2007) Yokoyama et al. (2007)

19. Pre-solar grains and predictions There is more than binary mixing Lugaro et al. (2003) Loss of consistency for different elements

20. Issues: • Do nucleosynthetic components have discrete isotopic properties? • How many components are needed to account observations (deconvolution)? • Which mineral or organic phases are the carriers?

21. II Field shift

22. Nuclear field shift a.k.a.

23. Nuclear field shift effect of nuclear charge radius Point-charge approximation Breit (1958)

24. Nuclear field shift:effect of nuclear shape

25. is the difference in nuclear charge radii between nuclei of mass m and m’, A and B are constants Bigeleisen’s (1996) formulation of mass fractionation mass independent 1/T mass dependent 1/T2

26. Temperature dependence of isotope fractionation between U(IV) and U(VI) Mass-independent fractionation remains after internal normalization! Sites: gas-dust interaction Bigeleisen (1998)

27. Evidence of non-mass dependent fractionation experiment between crown-ether and acid solution Fujii et al. (2006) Further evidence from elution on ion-exchange resins

28. Hf nuclear charge radii increase smoothly Levins et al.(1999)

29. Zr: deformation of nucleus increases past the neutron closed-shell (N=50) N=50 Campbell et al. (1997)

30. Odd-even staggering of Sn nuclear properties Suggests using even-even or odd-odd for normalization!

31. Odd-even staggering of nuclear masses Ni Begs the question of which process control mass fractionation

32. Test for an effect of nuclear field shift internally normalized to Fujii et al. (2006)

35. Mo isotopes in carbonaceous chondrites Fujii et al. (2006)

36. The origin of the 54Cr anomaly Extraction experiments (Fujii et al, 2002) 54 50 53 52 Neutron cross-sections do not separate 54Cr from 52Cr, nuclear field shift does Trinquier et al. (2006)

37. III Analytical issues(or the limits of mass-dependent fractionation)

38. Correction for analytical and instrumental mass bias assumes constant isotopic abundances Chen et al. (2003)

39. Anomalous behavior of 125Te Moynier et al. (2006) Fehr et al.’ (2006) data renormalization

40. Risky normalisation (odd/even ratio) Also 61Ni

41. Pb: the double closed shell at mass 208(Z=82, N=126)

42. Odd-even staggering of Pb isotopes(extended spectrum) Sakakihara et al. (2001)

43. Pb Analytical mass fractionation Odd-even staggering and instrumental bias Blichert-Toft et al. (2003) Doucelance et al. (2001)

44. Conclusions • The number of nucleosynthetic components needs to be more rigorously evaluated • The strength of the nuclear field shift effect w.r.t. nucleosynthetic anomalies still unclear • Odd-even staggering of nuclear properties is ubiquitous and its cause is multiple: neutron cross-sections, nuclear field radii, and masses

45. Mo

46. Sm

47. Sm Carlson et al. (2007)

48. r-process nuclide abundances Arnould et al. (2007)

49. Mo

50. Mo isotopic anomalies in carbonaceous chondrites Allende Orgueil Yin et al. (2002) Dauphas et al. (2002)