Spectroscopy of neutron-richDy168,170: Yrast band evolution close to theNp

Abstract

The yrast sequence of the neutron-rich dysprosium isotope 168 Dy has been studied using multinucleon transfer reactions following collisions between a 460-MeV 82 Se beam and an 170 Er target. The reaction products were identified using the PRISMA magnetic spectrometer and the γ rays detected using the CLARA HPGe-detector array. The 2 + and 4 + members of the previously measured ground-state rotational band of 168 Dy have been confirmed and the yrast band extended up to 10 + . A tentative candidate for the 4 + → 2 + transition in 170 Dy was also identified. The data on these nuclei and on the lighter even-even dysprosium isotopes are interpreted in terms of total Routhian surface calculations and the evolution of collectivity in the vicinity of the proton-neutron valence product maximum is discussed.

Isomer Decay Spectroscopy ofSm164andGd166Patel1, Söderström2, Podolyák3 et al. 2014Phys. Rev. Lett.Self Cite589380View full textAdd to dashboardCite

“…Where such information exists (Z ≥ 70) there is no evidence for the deformed magicity of N ¼ 100. However, the anomalous Eð2 þ Þ behavior has been observed in Dy isotopes [9], and more prominently here in Gd and Sm isotopes, clearly highlighting complex deformation variations. This behavior gives support to the appearance of a deformed N ¼ 100 shell gap for Z ≤ 66, and this will influence r-process abundance calculations [5,6].…”

“…In this region, macroscopic-microscopic calculations [7] show a deformation maximum close to N ¼ 104 and Z ¼ 66 ( 170 Dy), which is simultaneously midshell for both neutrons and protons. However, these calculations seem to be contradicted by recent experimental data [8,9], which indicate either that the deformation maximum is at significantly lower proton and neutron numbers, or that there is more complex behavior, possibly due to energy gaps in the deformed single-particle space. In order to extend the experimental knowledge, and to test more recent theoretical calculations [10], we exploit a basic nuclear structure feature, namely, that deformation gives rise to long-lived nuclear excited states (isomers) [11].…”

Systematic study of multi-quasiparticleK-isomeric bands in tungsten isotopes by the extended projected shell model

“…In fact, 170 Dy represents the valence maximum (i.e., proton-neutron valence product N p N n ) in this region. However, the experimental results [52] do not support this idea. Recent theoretical calculation predicts a deformed shell closure at N = 100 [53].…”

β-γ and isomeric decay spectroscopy of 168Dy

“…Figure 2 shows the β-delayed γ-ray spectrum measured within 20 s after the implantation of 168 Tb. Before the present work, the excited states of 168 Dy had been studied by the β decay of 168 Tb [13] and multi-nucleon transfer reactions with a 82 Se beam incident on an 170 Er target [14]. The γ rays at energies of 75 and 173 keV, which were previously assigned as 2 Figure 3 shows the γ-ray spectrum measured within 350 ns ∼ 3 µs after the implantation of 168 Dy.…”