Abstract.Cross sections for the reactions zS2Sm(n ' p)152g, ml,m2pm ' 154Sm(n ' p)154g, mpm ' lVSHf(n ' p)17Sm, g Lu, 154Sm(n, d)153pm and 152Sm(n, c~)149Nd were measured at 14.5 MeV neutron energy by the activation method. On the basis of these cross sections, the associated isomeric ratios in ~Sapm, x52pm, 178Lu and the comparison with the predictions of different compound and precompound models, conclusions are drawn about the role of the preequilibrium processes in 14.5 MeV neutron induced reactions. Calculations for equal angular momentum removal by equilibrium and preequilibrium emitted particles better reproduced the experimental isomeric ratios, than for higher angular momentum removal in the preequilibrium phase. The isomeric ratios may be used as a source of additional information about the spin of the isomeric states in ~52Pm and IS4pm for which the spectroscopic information is uncertain.

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Activation cro~-sections for neutron capture have been measured st an energy of 14.5 MeV for lS~ relative to a(le~ = 1975 mb. Gamma-ray spectra of the product nur were messured with a HP Ge-detector. By systeraatically vaxying the geometrical arranseraent the correctior-= due to the influence of lower enexgy neutrons could be determined. The corrected activation c&pture ~section st 14.5 MeV is found to be 1.0 4" 0.2 mb.

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