Energy Dependence Of The Astrophysical S Factor For The Li-6(P, Gamma)Be-7 Reaction

Polarized proton beams with energies from 80 to 130 keV have been used to determine the slope of the astrophysical S factor for the Li-6(p, gamma(0))Be-7 and Li-6(p, gamma(1))Be-7 reactions. The slope was determined from the relative yields at five incident proton energies. The slope of the S factor was found to be negative. The analyzing power measurements indicate that the reaction proceeds predominately by s-wave capture. The negative slope does not appear to be due to low-binding-energy effects, the effects of nearby resonances, or electron screening of the nuclei. A resonating group model calculation demonstrates a new mechanism for producing a negative slope at astrophysically relevant energies in radiative capture reactions.