MEASUREMENTS OF ABSOLUTE AND RELATIVE EMISSION PROBABILITIES OF GAMMA-RAYS AND X-RAYS AND DATA EVALUATION IN THE DECAY OF EU-155

More accurate values for the X- and gamma-ray emissions of Eu-155 woul d be useful for improving the efficiency calibration of detectors in t he low-energy region. Samples of Eu-155 were produced by neutron irrad iation of high-purity Sm-154 (99.2%). The resulting solution consisted of 99.7% Eu-155, With impurities of Eu-152 (< 0.1%) and Eu-154 (< 0.2 %). 4 pi beta gamma coincidence equipment was used to determine the sp ecific activity of Eu-155. Absolute and relative photon emission proba bilities were measured with a Ge-planar spectrometer, which was calibr ated on the basis of generalized energy response functions. Spectral d istortions were taken into consideration to obtain precise values for the absolute and relative emission probabilities of X-rays and low-ene rgy gamma-rays. Re-evaluation of Eu-155 gamma- and X-ray emission prob abilities and half-life has been performed using the results of our me asurements and new data published in the literature.