Measurement of the Cascade Transition via the First Excited State of {sup 16}O in the {sup 12}C({alpha},{gamma}){sup 16}O Reaction, and Its S Factor in Stellar Helium Burning

Journal Article · Fri Dec 15 00:00:00 EST 2006 · Physical Review Letters

DOI:https://doi.org/10.1103/PHYSREVLETT.97.242503· OSTI ID:20861476

Matei, C; Brune, C R ^[1]; Buchmann, L; Hutcheon, D A; Caggiano, J; Laird, A; Li, ZH; Olin, A; Ottewell, D; Ruprecht, G; Trinczek, M ^[2]; Hannes, W R ^[3]; Ruiz, C; D'Auria, J; Lamey, M; Vockenhuber, C; Wrede, C ^[4]; Chen, A A; Pearson, J ^[5]; Liu, WP ^[6]

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1. Ohio University, Athens, Ohio (United States)
2. TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, V6T 2A3 (Canada)
3. University of Konstanz, Department of Physics (Germany)
4. Simon Fraser University, Burnaby, British Columbia (Canada)
5. McMaster University, Hamilton, Ontario (Canada)
6. China Institute of Atomic Energy, Beijing (China)

Radiative {alpha}-particle capture into the first excited, J{sup {pi}}=0{sup +} state of {sup 16}O at 6.049 MeV excitation energy has rarely been discussed as contributing to the {sup 12}C({alpha},{gamma}){sup 16}O reaction cross section due to experimental difficulties in observing this transition. We report here measurements of this radiative capture in {sup 12}C({alpha},{gamma}){sup 16}O for center-of-mass energies of E=2.22 MeV to 5.42 MeV at the DRAGON recoil separator. To determine cross sections, the acceptance of the recoil separator has been simulated in GEANT as well as measured directly. The transition strength between resonances has been identified in R-matrix fits as resulting both from E2 contributions as well as E1 radiative capture. Details of the extrapolation of the total cross section to low energies are then discussed [S{sub 6.0}(300)=25{sub -15}{sup +16} keV b] showing that this transition is likely the most important cascade contribution for {sup 12}C({alpha},{gamma}){sup 16}O.

• OSTI ID: 20861476
• Journal Information: Physical Review Letters, Vol. 97, Issue 24; Other Information: DOI: 10.1103/PhysRevLett.97.242503; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0031-9007
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ALPHA PARTICLES
ALPHA REACTIONS
CAPTURE
CARBON 12 TARGET
CENTER-OF-MASS SYSTEM
EXCITATION
EXCITED STATES
EXTRAPOLATION
GAMMA RADIATION
HELIUM BURNING
MEV RANGE 01-10
OXYGEN 16
R MATRIX
STAR EVOLUTION
TOTAL CROSS SECTIONS