The spectroscopy of^161,162ER at spins up to 50ℏ in the unpaired regime

Abstract

High spin states in I6lEr and I6'Er have been populated using the 13' ?e + 36S reaction at a 36S bombarding energy of 170 MeV. In I6'Er, three rotational bands were extended from Z=35h to Z=50h. In I6*Er the lowest energy positive parity band was observed to I = 44h and two negative parity bands to Z = 32h. The behaviour of these rotational sequences are explained in terms of the expected spectrum of single neutron states in the absence of static neutron pair correlations.

High resolution gamma-ray spectroscopy and the fascinating angular momentum realm of the atomic nucleus

“…In a series of experiments, which began at Daresbury Laboratory on the TESSA 2 and 3 and Eurogam arrays, then Euroball at Legnaro National Laboratory in Italy and Gammasphere at Lawrence Berkeley National Laboratory in the USA, the transitional nuclei 159 Er-162 Er [115][116][117][118] have been observed to very high spin (I=50-60ÿ), see figure 21.…”

“…The neutron orbital scheme was extended to the highspin states (∼45−50ÿ) in 161,162 Er observed in a subsequent experiment where it once more was found to be surprisingly successful [116]. The schematic single-neutron Routhians used for 161,162 Er are shown in figure 23(a).…”

Structural behavior of 157,158,159Dy in the I=30−50ħ spin regime and the high-spin domain of 158Er up to and above band termination

“…However, at very high rotational frequency there are known instances where the observed alignment gains in certain configurations do not fall within the standard CSM-plus-pairing framework. Such occurrences have been investigated in the N =91−94 Er isotopes [96,98,99].…”