Ca40(p, γ)Sc41Reaction

Proton capture by ${\mathrm{Ca}}^{40}$ has been studied by means of observations of both the prompt gamma rays from resonance states in the compound nucleus and the delayed positrons from the decay of the ground state. Targets of CaO were prepared by the electrodeposition of Ca onto a Pt backing followed by the oxidation of the Ca and the purging of impurities by heat. These targets were bombarded by protons from a 2-Mv Van de Graaff accelerator, producing the reaction ${\mathrm{Ca}}^{40}(p, \gamma ){\mathrm{Sc}}^{41}$. The gamma rays from this reaction were observed with the use of a 3-in. diam by 3-in. NaI(Tl) crystal and a 256-channel pulse-height analyzer. Positrons from the decay of ${\mathrm{Sc}}^{41}$ were detected with the use of a thin plastic phosphor, 1.5 in. diam by 0.012 in. thick. Two resonances in the reaction were observed at bombarding energies of 650±5 kev and 1850±10 kev. Two other possible resonances were observed at 1550±15 kev and 1630±15 kev. The 650-kev resonance corresponds to an excited state in ${\mathrm{Sc}}^{41}$ at 1.723±0.011 Mev, has an integrated cross section of 0.02 ev barn (factor of 2 uncertainty either way), has a width of less than 5 kev, and involves a gamma ray whose energy was measured to be 1.71±0.03 Mev. The 1850-kev resonance corresponds to an excited state in ${\mathrm{Sc}}^{41}$ at 2.883±0.014 Mev, has an integrated cross section of 0.3 ev barn (factor of 2 uncertainty either way), has a width of less than 10 kev, and involves a gamma ray whose energy was measured to be 2.89±0.02 Mev.