Decay of 161Er to 161Ho

Abstract

The level scheme of the deformed odd-proton nucleus 161Ho was investigated in the electron-capture decay of 161Er using germanium detectors, a magnetic β-spectrograph and two π√2 double-focussing β-spectrometers. In addition to the measurements of singles γ-ray and conversion-electron spectra extensive γ-γ coincidence measurements were performed. A decay scheme is proposed involving 37 excited states in 161Ho. In the low-energy region the first members of the rotational bands 7 2 -[523], 1 2 +[411], 7 2 +[404], 3 2 +[4411], 1 2 −[541], 5 2 +[413] and 5 2 −[532] were identified. Furthermore, the first two members of the γ-vibrational band K 0-2 M built on the ground state and an additional band with the probable quantum characteristic K π = 5 2 + (band head at 446.9 keV) have been found. Possible interpretations of the high-lying levels are discussed on the basis of current models.