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Experimental Determination of 𝛼 Widths of 21Ne Levels in the Region of Astrophysical Interest: New 17O +𝛼 Reaction Rates and Impact on the Weak 𝑠 Process

Journal Article · · Physical Review Letters
 [1];  [2];  [3];  [1];  [1];  [4];  [5];  [6];  [4];  [7];  [8];  [9];  [1];  [10];  [9];  [4];  [3];  [11];  [7]
  1. Université Paris-Saclay, Orsay (France)
  2. Univ. of the Witwatersrand (South Africa); iThemba Laboratory for Accelerator Based Sciences (South Africa)
  3. Istituto Nazionale di Fisica Nucleare (INFN) (Italy); Univ. of Catania (Italy); Centro Siciliano di Fisica Nucleare e Struttura della Materia (Italy)
  4. Centre National de la Recherche Scientifique (CNRS), Caen (France). Grand Accelerateur National d'Ions Lourds (GANIL)
  5. Univ. Libre, Brussels (Belgium)
  6. Technische Univ. München, Garching (Germany)
  7. Ludwig Maximilian Univ. of Munich, Munich (Germany)
  8. Keele Univ. (United Kingdom); Univ. of Tokyo (Japan)
  9. Istituto Nazionale di Fisica Nucleare (INFN) (Italy)
  10. Univ. degli Studi di Perugia (Italy); Istituto Nazionale di Fisica Nucleare (INFN) (Italy)
  11. Istituto Nazionale di Fisica Nucleare (INFN) (Italy); Univ. degli Studi di Enna (Italy)
+ Show Author Affiliations
The efficiency of the weak 𝑠 process in low-metallicity rotating massive stars depends strongly on the rates of the competing 17O ⁡(𝛼,𝑛)⁢ 20Ne and 17O ⁡(𝛼,𝛾)⁢ 21Ne reactions that determine the potency of the 16O neutron poison. Their reaction rates are poorly known in the astrophysical energy range of interest for core helium burning in massive stars because of the lack of spectroscopic information (partial widths, spin parities) for the relevant states in the compound nucleus 21Ne . In this Letter, we report on the first experimental determination of the 𝛼-particle spectroscopic factors and partial widths of these states using the 17O ⁡(7Li, 𝑡)⁢21Ne 𝛼-transfer reaction. With these the 17O ⁡(𝛼, 𝑛)⁢20Ne and 17O ⁡(𝛼, 𝛾)⁢ 21Ne reaction rates were evaluated with uncertainties reduced by a factor more than 3 with respect to previous evaluations and the present 17O ⁡(𝛼, 𝑛)⁢ 20Ne reaction rate is more than 20 times larger. Finally, the present (𝛼, 𝑛)/(𝛼, 𝛾) rate ratio favors neutron recycling and suggests an enhancement of the weak 𝑠 process in the Zr-Nd region by more than 1.5 dex in metal-poor rotating massive stars.
Research Organization:
Texas A & M Univ., College Station, TX (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Nuclear Physics (NP)
Grant/Contract Number:
FG02-93ER40773
OSTI ID:
3000119
Journal Information:
Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 18 Vol. 132; ISSN 1079-7114; ISSN 0031-9007
Publisher:
American Physical Society (APS)Copyright Statement
Country of Publication:
United States
Language:
English

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