First search for double β decay of dysprosium

The energy spectrum accumulated with the Dy2O3 sample by the HPGe detector is shown (red line) together with the background data (black line). The spectra are normalized on the times of measurements. The radioactive contaminations of the Dy2O3 sample have been deeply investigated.

No clear peculiarities in the energy spectra accumulated with the dysprosium sample can be interpreted as double beta decay of 156Dy or 158Dy. Obtained half-life are: and and .

In the figure the low energy part of energy spectrum accumulated with the sample over 2512 h is shown. An excluded effect of 2ν2K process in 156Dy (158Dy) with half-life T1/2 = 6.1 X 1014 yr (T1/2 = 1.0 X 1015 yr), and 2ν2ε transition of 156Dy to the first excited level of 156Gd (89.0 keV, T1/2 = 1.8 X 1014 yr) are shown by solid lines.