Fletcher Gabbard

The proton‐90Zr interaction at sub‐coulomb proton energies

Measurements have been made of proton elastic scattering differential cross sections for proton scattering at 135° and 165° from 2 to 7 MeV, of inelastic scattering cross sections for proton scattering from 3.9 to 5.7 MeV, and of the radiative capture cross sections from 1.9 to 5.7 MeV detecting primary and cascade gamma rays. Optical potentials with Hauser‐Feshbach and coupled‐channel models have been used to analyze the data. This analysis yields an energy dependent absorptive potential of W=2.63+.73 whose mean value of 5 MeV at Ep=4 MeV is consistent with previously reported, but anomalously small values. The diffuseness of the real potential is .54 fm, which is consistent with values found for 92Zr and 94Zr. The adopted model values are used to deduce a total proton strength function which displays the features of both the 3s and the 3p single particle resonances.

Total (p,n), (p,γ), (p,p’γ) and differential (p,p) cross‐sections measurements for 61,64Ni

Absolute total (p,n) and differential elastic (p,p) cross sections have been measured for 61,64Ni in the energy range of Ep=2 to 7 MeV. The (p,γ) and (p,p’γ) cross sections were measured from as low an energy as feasible to approximately one MeV above the (p,n) threshold. Standard optical potentials have been used with a Hauser‐Feshbach model to analyze the data. The adopted model values are used to deduce a total proton strength function which displays features of the 3s single particle resonance.

Reactions rates of (p,n) and (α,n) reactions important to nucleosynthesis

The use of a 6 MV Van de Graaff accelerator for the studies of (p,n) and (α,n) reactions in intermediate mass nuclei is described with particular emphasis on the measurement of proton strength functions in the atomic-mass range from 88 to 124. The neutrons are detected in a 60-cm-diameter polyethylene sphere detector with an efficiency which is independent of energy for neutrons having energies between 30 keV and 2.5 MeV. In some cases, cross sections for the inverse reactions have been obtained using the principle of detailed balance. Nucleosynthesis reaction rates NA (σv) have been determined in most cases. The (p,n) reaction studies are of interest in establishing reaction systematics for p-process nuclei.