Decay of Gd¹⁵³

Abstract

The decay by electron capture of Gd¹⁵³ (half-life 236 days) is studied with a coincidence Scintillation Spectrometer. Two gamma-rays are observed with energies 72±8 keV and 100±4 keV and relative intensities of 7:100. Both these gamma-rays are coincident with K X-rays of Eu. From the coincidence data the K-shell conversion coefficient of the 100 keV gamma transition has been determined to be 0.67±0.12; the comparison with theory then leads to assigning this gamma-ray predominantly to a magnetic dipole transition. From the experimental L/K capture ratio the energy involved in the capture process is estimated. Our results show that the levels in Eu¹⁵³ which are reached by the capture decay of Gd¹⁵³ are not identical with the levels that were observed in coulomb excitation of Eu. On the basis of our findings we propose a decay scheme for Gd¹⁵³.