Measurements and evaluation of absolute emission probabilities for soft photons of 153Gd, 155Eu and 169Yb

Absolute emission probabilities of Kx- and γ-rays in the energy region 40–200 keV have been obtained for 153Gd and 155Eu using measurements of emission rates by Ge, Ge(Li) and Si(Li)-detectors and of activities by a 4δβ-γ coincidence system. The main results of our measurements and evaluation of decay data of 153Gd and 155Eu were published in 1992 and 1994. Here new experimental data concerning soft photon radiation which were obtained with a new Si(Li) spectrmeter calibrated on the basis of a generalized energy response function are presented. For the 14.06 keV γ-ray in the decay of 153Gd a value of (0.029±0.003) photons per 100 disintegrations has been measured. For 155Eu the absolute emission probabilities of Kx- and 26.5, 45.3, 58.0, 60.0 γ-rays have been measured using the Si(Li) (formerly only a Ge-detector was used). A re-evaluated value of the 153Gd half-life is reported. For 169Yb the evaluation of decay data has been carried out taking into account the results of the latest measurements of absolute emission probabilities of γ-rays with energies 63.12, 109.80, 130.52 and 197.96 keV.