1 / 11

Neutron Capture Measurements of Bismuth and Lead Isotopes

The n_TOF Collaboration. Neutron Capture Measurements of Bismuth and Lead Isotopes. Jose L. Tain Instituto de Fisica Corpuscular CSIC-Univ.Valencia. Layout: Motivation Experimental details 209 Bi(n, ) and 207 Pb(n, ) results Conclusions. Motivation:. Astrophysics.

lynley
Download Presentation

Neutron Capture Measurements of Bismuth and Lead Isotopes

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. The n_TOF Collaboration Neutron Capture Measurements of Bismuth and Lead Isotopes Jose L. Tain Instituto de Fisica Corpuscular CSIC-Univ.Valencia • Layout: • Motivation • Experimental details • 209Bi(n,) and 207Pb(n,) results • Conclusions

  2. Motivation: Astrophysics • Termination region of the s-process path: • stellar site • r-process abundances • Th/U cosmo-chronometers (n,) -decay -decay

  3. Motivation: ADS Sub-critical system for the transmutation of nuclear waste with Pb or Pb/Bi spallation-target/coolant Neutron balance: Radio-toxicity: • 210mBi (3x106 y) • 210Po (138 d)

  4. Set-up sample changer C6D6 C6D6 n-beam Experimental details: • Challenges: • very small capture cross section • large scattering to capture ratio • few percent accuracy Use C6D6 detectors and setup with reduced neutron sensitivity Samples & beam-time:

  5. 1.15keV @56Fe Experimental details: Accuracy of the Pulse Height Weighting Technique? (used to count properly capture cascades) Use of detailed MC simulations of detector response with the full setup + Use of the nuclear statistical model to make systematic corrections … accuracy < 2%

  6. RK=18.2(5%) meV RK=12(7%) meV 209Bi(n,) Results: neutron sensitivity! n_TOF vs. previous experiments

  7. RK=18.2(5%) meV RK=12(7%) meV 209Bi(n,) Results: neutron sensitivity! n_TOF vs. Evaluated Data Files and compilations

  8. 207Pb(n,) Results: n_TOF vs. previous experiments incorrect WF ! not included …

  9. 207Pb(n,) Results: n_TOF vs. Evaluated Data Files and compilations incorrect WF ! not included …

  10. 204Pb under progress … 206Pb under progress … poor peak/background ratio due to sample scattered in-beam -rays 208Pb

  11. Conclusions: • Cross sections with improved accuracy have been obtained and they point out to the need of updating Evaluated Data Bases • Astrophysics implications: slight reduction of Bi abundance calculated in low metallicity TP-AGB stars • ADS implications: larger production of long term radiotoxic210mBi • Extension of the measurements with this improved setup to higher energies are very desirable and possible with a reduction of in-beam -ray background

More Related