Yield Ratios of Isomers Produced by Neutron Activation

Abstract

Values of the yield ratios of 14 pairs of isomers (${\mathrm{Co}}^{60,60m}$, ${\mathrm{Zn}}^{69,69m}$, ${\mathrm{Se}}^{81,81m}$, ${\mathrm{Br}}^{80,80m}$, ${\mathrm{Rb}}^{86,86m}$, ${\mathrm{Rh}}^{104,104m}$, ${\mathrm{Ag}}^{110,110m}$, ${\mathrm{In}}^{114,114m}$, ${\mathrm{Sb}}^{122,122m}$, ${\mathrm{Te}}^{127,127m}$, ${\mathrm{Cs}}^{134,134m}$, ${\mathrm{Ce}}^{137,137m}$, ${\mathrm{Eu}}^{152,152m}$, and ${\mathrm{Ir}}^{192,192m}$) produced by thermal neutron activation are given. The values are compared with those calculated by the method of Huizenga and Vandenbosch. From this comparison, the spins of several compound nuclei are indicated. Comparison of isomer yield ratios measured with thermal and with epi-cadmium neutrons are given for 7 pairs (${\mathrm{Rh}}^{104,104m}$, ${\mathrm{In}}^{114,114m}$, ${\mathrm{In}}^{116,116m}$, ${\mathrm{Cs}}^{134,134m}$, ${\mathrm{Eu}}^{152,152m}$, ${\mathrm{Ta}}^{182,182m}$, and ${\mathrm{Ir}}^{192,192m}$). These are discussed in terms of the spins of the compound nucleus which are associated with different neutron absorption resonances. New thermal neutron cross-section values are given for the formation of 9 nuclides (${\mathrm{Co}}^{60m}$, ${\mathrm{Rb}}^{86m}$, ${\mathrm{Rb}}^{86}$, ${\mathrm{Ag}}^{110}$, ${\mathrm{In}}^{114m}$, ${\mathrm{In}}^{114}$, ${\mathrm{Ir}}^{192m}$, ${\mathrm{Ir}}^{192}$, and ${\mathrm{Ir}}^{194}$).