Average cross-sections for /n, p/ reactions on calcium in a fission-type reactor spectrum

The average cross-section in a fission-type reactor spectrum sigmasub(F) was experimentally determined for the reactions 42Ca/n,p/42K, 43Ca/n,p/43K and 44Ca/n,p/44K. Calcium carbonate samples and fast neutron flux monitors were irradiated with and without cadmium shielding in the Thetis reactor (Institute for Nuclear Sciences, Rijksuniversiteit Gent). The potassium activities induced in the calcium carbonate samples were separated and purified by tetraphenylborate precipitation, after which they were measured with a Ge/Li/-detector of calibrated detection efficiency. On the basis of sigmasub(F)=0.64 mb for the reaction 27Al/n,α/24Na, the average cross-sections were as follows: 42Ca/n,p/42K: 2.82+-0.07 mb; 43Ca/n,p/43K: 1.89+-0.05 mb; 44Ca/n,p/44K: 0.065+-0.003 mb. (T.G.)