1 / 28

Results on 62,63 Ni(n,  )

Results on 62,63 Ni(n,  ). Claudia Lederer Goethe University Frankfurt. Outline. 63 Ni(n,  ) measurement resonances MACS and astrophysical impact 62 Ni(n,  ) 62 Ni Resonances 62 Ni MACS. 63 Ni measurement. samples measured (protons for filter runs in brackets):.

jania
Download Presentation

Results on 62,63 Ni(n,  )

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Results on 62,63Ni(n,) Claudia Lederer Goethe University Frankfurt

  2. Outline 63Ni(n,) • measurement • resonances • MACS and astrophysical impact 62Ni(n,) • 62Ni Resonances • 62Ni MACS

  3. 63Ni measurement • samples measured (protons for filter runs in brackets): * dedicated pulses, extracted by TTOFsort

  4. 63Ni Capture Yield

  5. 63Ni Resonances • 12 Resonances identified and fitted up to 55 keV • from 10 keV unresolved cross section with larger energy bins • Yield cross section: neglects MS, Oxygen cross section (NiO sample), other impurities

  6. 63Ni Resonances • 12 Resonances identified and fitted up to 55 keV • from 10 keV unresolved cross section with larger energy bins • Yield cross section: neglects MS, Oxygen cross section (NiO sample), other impurities

  7. 63Ni Resonances

  8. MACS • Combination of RRR (< 10 keV) and URR (>10 keV)

  9. MACS • Combination of RRR (< 10 keV) and URR (>10 keV) =20-22% almost accepted by PRL

  10. Stellar rates • At high temperatures neutron capture may also happen on excited states • 63Ni levels: 87.15 keV, 155.55 keV, 517.55 keV • for kT=90 keV only 30-40% of neutron captures on ground state • Stellar rate combination of measurement and theory • see papers by T. Rauscher (Int. J. Mod. Phys. 20, 1071 (2011), ApJ 738, 143 (2011), ApJS 201, 26 (2012)) 

  11. Astrophysical implications Two burning stages in massive stars: • He Core burning: kT~26 keV, Nn~106 cm-3 • Carbon shell burning: kT~90 keV, Nn~1011 cm-3 64Zn 65Zn 244 d 66Zn 67Zn 68Zn 62Cu 9.7 m 63Cu 64Cu 12.7 h 65Cu 66Cu 5 m 60Ni 61Ni 62Ni 63Ni 102 a 64Ni 65Ni 2.5 h 58Co 70 d 59Co 60Co 5.3 a 61Co 1.7 h 62Co 14 m 63Co 28 s 56Fe 57Fe 58Fe 59Fe 45 d 60Fe 106 a 61Fe 6 m

  12. Astrophysical implications Rel. to Kadonis: 63Cu/65Cu smaller Link to observed Cu abundances difficult due to explosive nucleosynthesis during SN explosion. 

  13. 62Ni(n,): Resonances • Resonances fitted up to 200 keV • New resonances: 2128 eV, 12.2, 20.6, 29.96, 57.6, 67.9, 70.9, 81.5, 97.6, 147, 149, 170, 181 keV • Total 42 resonances fitted for 2009 and 2011 data

  14. 62Ni(n,): Resonances • 62Ni too thick to fit that resonance -> use 63Ni yield • Fit of  using previous measurements of n 2g 62Ni sample

  15. 62Ni(n,): Resonances • Results from fit: • n=2075 eV: ER=4621 eV, =2.687 eV (l=0) • n=1822 eV: ER=4607 eV, =2.401 eV (l=0) • Thermal xs: • 16.4 b • 12.9 b • 14.2 b • 62Ni too thick to fit that resonance -> use 63Ni yield • Fit of Gg using previous measurements of Gn

  16. 62Ni(n,): Capture Kernels • 62Ni too thick to fit that resonance -> use 63Ni yield • Fit of Gg using previous measurements of Gn

  17. Uncertainties of MACS • WFs: 2% • Normalization: 1% • Flux: 5% (since region between 8-80 keV is most important) • BIF(En): 0.5% • 4.6 keV Res: 4%-1% (5keV – 90 keV) • Statistics: 0.7%-5.9% (5keV-90keV) • Total: 6.9%-8.1% •  Most accurate measurement so far + covering the widest energy range!

  18. MACS RPs up to 200 keV (n_TOF), then JENDL

  19. MACS

  20. MACS

  21. MACS

  22. Level Density • fit: #(levels)=a*Energy+b • a= 0.000321, b=0.7 • 190 keV -> 61 levels expected, observed 42

  23. THE END

  24. 63Ni Pointwise Cross Section

  25. 63Ni Pointwise Cross Section XS at 0.025 eV ~35 b XS resonances ~ 20 b Exp. Values: 15-30b

  26. MACS statistical uncertaintiy • Fit result from capture measurement: Kernel Ag=gn/(n+) Area of the resonance 

  27. MACS statistical uncertaintiy • Fit result from capture measurement Kernel Ag=gn/(n+) Area of the resonance • Statistical error with W=ERexp(-ER/kT) is: 

  28. Uncertainties of Kernels and MACS • 2 datasets: 2009 and 2011 • 2 sets of resonance parameters • Final capture kernel is weighted mean value of 2009 and 2011 kernel • Uncertainty of Kernel is the max. of propagated uncertainty of fit and standard deviation • MACS: 4 sets of MACS (2009, 2011, two different fits of 4.6 keV resonance): • Step 1: mean value of 2009 and 2011 for the 2 different versions with statistical uncertainty derived from averaged capture kernels • Step 2: average for the 2 different fits at 4.6 keV where the standard deviation enters into the systematic uncertainty of the MACS

More Related