Positron decay of 153Dy

Positron spectrum of the 153Dy → 153Tb decay was investigated by means of the iron-free β-spectrometer with a toroidal magnetic field. Maximum spectrometer transmission constituted approximately 20% and resolving power was 1.1%. The 153Dy sources are preparaed by introduction of the 153Dy ions into the aluminium substrate 0.68 mgxcm-2 thick (four sources) and 1.85 mgxcm-2 thick (three sources). The positron decay spectrum was determined to be complicated; it consisted of three components with the boundary energies of 1069+-10, 886+-2 and 427+-22 keV and with relative intensities of 0.17+-0.03, 1.0 and 0.06+-0.02, respectively. The 153Dy → 153Tb mass difference is determined to be equal to 2171+-2 keV. Analysis of the data obtained and their comparison with the available data does not permit to make a conclusion about the positron 153Dy decay intensity and about epsilon/β+ value