J. Hoste

THE

Summary The mean fission neutron cross sections of the 127I(n, p)127mTe; 127I(n, p)127Te and 127I(n, 2n)126I reactions were determined experimentally from the absolute 127mTe, 127Te and 128I activities induced in irradiated potassium iodide. For this purpose a quantitative separation method for tellurium from iodine was developed using liquid-liquid extraction of iodine and precipitation of tellurium by means of hydrazine hydrate. The absolute tellurium activity was measured with a calibrated Geiger-Müller tube whereas the iodine activity was measured by gamma spectrometry. For the cross sections of the reactions 127I(n, p)127mTe and 127I(n, p)127Te respective values of 11.1 ± 0.2 μbarn and 7.62 ± 0.11 μbarn were obtained. For the cross section of the reaction 127I(n, 2n)126I a value of 0.647 + 0.010 μbarn was found.

sup 127

The cross-section for the reaction 1 8 1 T a (n, p) 1 8 1 H f averaged over the fission neutron spectrum was determined experimentally from the 1 8 1 H f activity induced in irradiated T a 2 0 5 . The T a 2 O s target was purified by liquid-liquid extraction with methylisobutylcetone from a H 2 S 0 4 H F solution. The induced 1 8 1 H f activity was separated and purified using anion exchange in hydrochloricoxalic acid medium. The 1 8 1 H f activity was measured by fast-slow coincidence spectrometry. A value of 1.2 ± 0.3 Mbarn was obtained for the cross-section.