Direct Measurement of the C13(α,n)O16 Cross Section into the s-Process Gamow Peak

G. F. Ciani et al. (LUNA Collaboration)
Phys. Rev. Lett. 127, 152701 – Published 5 October 2021
PDFHTMLExport Citation

Abstract

One of the main neutron sources for the astrophysical s process is the reaction C13(α,n)O16, taking place in thermally pulsing asymptotic giant branch stars at temperatures around 90 MK. To model the nucleosynthesis during this process the reaction cross section needs to be known in the 150–230 keV energy window (Gamow peak). At these sub-Coulomb energies, cross section direct measurements are severely affected by the low event rate, making us rely on input from indirect methods and extrapolations from higher-energy direct data. This leads to an uncertainty in the cross section at the relevant energies too high to reliably constrain the nuclear physics input to s-process calculations. We present the results from a new deep-underground measurement of C13(α,n)O16, covering the energy range 230–300 keV, with drastically reduced uncertainties over previous measurements and for the first time providing data directly inside the s-process Gamow peak. Selected stellar models have been computed to estimate the impact of our revised reaction rate. For stars of nearly solar composition, we find sizeable variations of some isotopes, whose production is influenced by the activation of close-by branching points that are sensitive to the neutron density, in particular, the two radioactive nuclei Fe60 and Pb205, as well as Gd152.

  • Figure
  • Figure
  • Figure
  • Received 11 April 2021
  • Revised 8 June 2021
  • Accepted 17 August 2021

DOI:https://doi.org/10.1103/PhysRevLett.127.152701

© 2021 American Physical Society

Physics Subject Headings (PhySH)

Nuclear Physics

Authors & Affiliations

Click to Expand

Article Text (Subscription Required)

Click to Expand

Supplemental Material (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 127, Iss. 15 — 8 October 2021

Reuse & Permissions
Access Options
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review Letters

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×