Activation cross sections for reactions induced by 14.7-MeV neutrons on natural calcium and enriched Ca-44 targets

Using 14.7-MeV neutrons and gamma-ray spectroscopy with high-purity germani um detectors, the activation cross sections have been measured for the foll owing nuclear reactions: (a) Ca-44(n,p)K-44, sigma = (39 +/- 4) mb; (b) Ca- 44(n,np)K-43, sigma = (3.0 +/- 0.3) mb; (c) Ca-44(n,ar)Ar-41, sigma = (31 /- 3) mb; (d) Ca-42(n,p)K-42, sigma = (138 +/- 12) mb; (e) Ca-43(n,p)K-43, sigma = (90 +/- 9) mb; and (f) Ca-48(n,2n)Ca-47, sigma = (613 +/- 60) mb. A 98.6% enriched Ca-44 target was used for reactions (a) (b) and(c) and a na tural calcium target for reactions (d) (e) and (f). These cross sections ha ve been compared with some earlier published experimental values and with s ome results of calculations. The latter include those based on semiempirica l formulas and those given by the preequilibrium plus compound-nucleus code GNASH. When applied to reactions (a), (d), (e), and(f), this code gives cr oss-section values that are consistently above the measured values.