Study of interference effects in the 18F(p, α) 15O reaction

K. Y. Chae, The University of Tennessee, Knoxville
M. W. Guidry, The University of Tennessee, Knoxville
C. D. Nesaraja, The University of Tennessee, Knoxville
Z. Ma, The University of Tennessee, Knoxville
D. W. Bardayan, ORNL Physics Division
J. C. Blackmon, ORNL Physics Division
M. S. Smith, ORNL Physics Division
D. Gregory, Tennessee Technological University
R. L. Kozub, Tennessee Technological University
S. Paulauskas, Tennessee Technological University
J. F. Shriner, Tennessee Technological University
N. Smith, Tennessee Technological University
M. S. Johnson, Oak Ridge Associated Universities
R. J. Livesay, Colorado School of Mines
M. Porter-Peden, Colorado School of Mines
S. D. Pain, Rutgers University–New Brunswick
J. S. Thomas, Rutgers University–New Brunswick


The 18F(p,α)15O reaction plays a crucial role in understanding g -ray emission from novae. Because of the importance of understanding the 18F + p reactions, a number of studies of the A=19 isobars have been made using stable and exotic beams. The interference effects among Jp = 3/2 + resonances in the 18F + p system, however, have never been measured, but they can change the S-factor by a factor of 20 at nova energies. R-matrix calculations indicate that the cross sections above the Ec.m. = 665 keV resonance are sensitive to the interference between the Ec.m. = 8, 38, and 665 keV resonances. In order to study the interference effects, an excitation function for the 1H( 18F,α)15O reaction has been measured in the energy range of Ec.m. = 663-877 keV using radioactive 18F beams at the Holifield Radioactive Ion Beam Facility. By measuring the 18F(p, α)15O cross section off resonance and comparing the cross section with theoretical calculations, we provide the first experimental constraints on the interference of 3/2 + resonances. © Copyright owned by the author(s).