Measurements of absolute and relative emission probabilities of gamma- and X-rays and data evaluation in the decay of 155Eu

Abstract

More accurate values for the X- and gamma-ray emissions of 155Eu would be useful for improving the efficiency calibration of detectors in the low-energy region. Samples of 155Eu were produced by neutron irradiation of high-purity 154Sm (99.2%). The resulting solution consisted of 99.7% 155Eu, with impurities of 152Eu (< 0.1%) and 154Eu ( < 0.2%). 4πβγ coincidence equipment was used to determine the specific activity of 155Eu. Absolute and relative photon emission probabilities were measured with a Ge-planar spectrometer, which was calibrated on the basis of generalized energy response functions. Spectral distortions were taken into consideration to obtain precise values for the absolute and relative emission probabilities of X-rays and low-energy gamma-rays. Re-evaluation of 155Eu gamma- and X-ray emission probabilities and half-life has been performed using the results of our measurements and new data published in the literature.