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Title: 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

Abstract

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.

Authors:
;  [1]; ; ; ; ; ; ; ; ;  [2];  [3]; ; ; ; ;  [4]; ;  [5];  [6]
  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)
Publication Date:
OSTI Identifier:
20861476
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Letters; Journal Volume: 97; Journal Issue: 24; Other Information: DOI: 10.1103/PhysRevLett.97.242503; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
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

Citation Formats

Matei, C., Brune, C. R., Buchmann, L., Hutcheon, D. A., Caggiano, J., Laird, A., Li, ZH., Olin, A., Ottewell, D., Ruprecht, G., Trinczek, M., Hannes, W. R., Ruiz, C., D'Auria, J., Lamey, M., Vockenhuber, C., Wrede, C., Chen, A. A., Pearson, J., and Liu, WP. 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. United States: N. p., 2006. Web. doi:10.1103/PHYSREVLETT.97.242503.
Matei, C., Brune, C. R., Buchmann, L., Hutcheon, D. A., Caggiano, J., Laird, A., Li, ZH., Olin, A., Ottewell, D., Ruprecht, G., Trinczek, M., Hannes, W. R., Ruiz, C., D'Auria, J., Lamey, M., Vockenhuber, C., Wrede, C., Chen, A. A., Pearson, J., & Liu, WP. 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. United States. doi:10.1103/PHYSREVLETT.97.242503.
Matei, C., Brune, C. R., Buchmann, L., Hutcheon, D. A., Caggiano, J., Laird, A., Li, ZH., Olin, A., Ottewell, D., Ruprecht, G., Trinczek, M., Hannes, W. R., Ruiz, C., D'Auria, J., Lamey, M., Vockenhuber, C., Wrede, C., Chen, A. A., Pearson, J., and Liu, WP. Fri . "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". United States. doi:10.1103/PHYSREVLETT.97.242503.
@article{osti_20861476,
title = {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},
author = {Matei, C. and Brune, C. R. and Buchmann, L. and Hutcheon, D. A. and Caggiano, J. and Laird, A. and Li, ZH. and Olin, A. and Ottewell, D. and Ruprecht, G. and Trinczek, M. and Hannes, W. R. and Ruiz, C. and D'Auria, J. and Lamey, M. and Vockenhuber, C. and Wrede, C. and Chen, A. A. and Pearson, J. and Liu, WP.},
abstractNote = {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.},
doi = {10.1103/PHYSREVLETT.97.242503},
journal = {Physical Review Letters},
number = 24,
volume = 97,
place = {United States},
year = {Fri Dec 15 00:00:00 EST 2006},
month = {Fri Dec 15 00:00:00 EST 2006}
}