skip to main content


This content will become publicly available on September 7, 2018

Title: The C 12 ( α , γ ) O 16 reaction and its implications for stellar helium burning

The creation of carbon and oxygen in our Universe is one of the forefront questions in nuclear astrophysics. The determination of the abundance of these elements is key to our understanding of both the formation of life on Earth and to the life cycles of stars. While nearly all models of different nucleosynthesis environments are affected by the production of carbon and oxygen, a key ingredient, the precise determination of the reaction rate of 12C (α, γ) 16O , has long remained elusive. This is owed to the reaction’s inaccessibility, both experimentally and theoretically. Nuclear theory has struggled to calculate this reaction rate because the cross section is produced through different underlying nuclear mechanisms. Isospin selection rules suppress the E 1 component of the ground state cross section, creating a unique situation where the E 1 and E 2 contributions are of nearly equal amplitudes. Experimentally there have also been great challenges. Measurements have been pushed to the limits of state-of-the-art techniques, often developed for just these measurements. The data have been plagued by uncharacterized uncertainties, often the result of the novel measurement techniques that have made the different results challenging to reconcile. However, the situation has markedly improved inmore » recent years, and the desired level of uncertainty ≈ 10 % may be in sight. In this review the current understanding of this critical reaction is summarized. The emphasis is placed primarily on the experimental work and interpretation of the reaction data, but discussions of the theory and astrophysics are also pursued. In conclusion, the main goal is to summarize and clarify the current understanding of the reaction and then point the way forward to an improved determination of the reaction rate.« less
 [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ; ORCiD logo [9] ;  [10] ;  [11]
  1. Univ. of Notre Dame, IN (United States). Joint Inst. for Nuclear Astrophysics, Dept. of of Physics
  2. Univ. of Toronto, ON (Canada). Dept. of Physics; Univ. of Notre Dame, IN (United States). Joint Inst. for Nuclear Astrophysics, Dept. of of Physics
  3. Istituto Nazionale di Fisica Nucleare (INFN), L'Aquila (Italy). Gran Sasso National Lab. (LNGS)
  4. Ohio Univ., Athens, OH (United States). Edwards Accelerator Lab., Dept. of Physics and Astronomy
  5. Michigan State Univ., East Lansing, MI (United States). Joint Inst. for Nuclear Astrophysics, Dept. of Physics and Astronomy
  6. Heidelberg Inst. for Theoretical Studies, Heidelberg (Germany)
  7. Univ. of Hull (United Kingdom). E. A. Milne Centre for Astrophysics, Dept. of Physics & Mathematics; Hungarian Academy of Sciences, Budapest (Hungary). Konkoly Observatory, Research Centre for Astronomy and Earth Sciences
  8. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  9. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics and Astronomy
  10. Arizona State Univ., Tempe, AZ (United States). Joint Inst. for Nuclear Astrophysics, School of Earth and Space Exploration
  11. Texas A & M Univ., College Station, TX (United States). Cyclotron Inst.
Publication Date:
Report Number(s):
LA-UR-17-30595; LLNL-JRNL-737639
Journal ID: ISSN 0034-6861; RMPHAT
Grant/Contract Number:
AC52-06NA25396; Phys-0758100; Phys-0822648; PHY 02-16783; PHY 09-22648; PHY-1430152; FG02-88ER40387; NA0002905; AC52-07NA27344
Accepted Manuscript
Journal Name:
Reviews of Modern Physics
Additional Journal Information:
Journal Volume: 89; Journal Issue: 3; Journal ID: ISSN 0034-6861
American Physical Society (APS)
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
National Science Foundation (NSF); USDOE; Ford Foundation; Michigan State University
Country of Publication:
United States
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; Atomic and Nuclear Physics; Nuclear Astrophysics
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1380012; OSTI ID: 1438667