Work

Lifetimes of negative parity states in $$^{162}$$Dy

Year: 2026

Type: article

Abstract: Lifetimes of excited states in $$^{162}$$ 162 Dy were measured using the (n,n’ $$\gamma $$ γ ) reaction with the Doppler-Shift Attenuation Method (DSAM) at the University of Kentucky’s Accelerator Laboratory. A total of eighteen level lifetimes were obtained, including eleven negative-parity states, seven of which are new. These measurements significantly expand the experimental database of transition probabilities for negative-parity bands in the well-deformed rare earth region of nuclei. The extracted B( E 1) and B( E 2) values reveal enhanced interband E1 ( $$10^{-3}$$ 10 - 3 or $$10^{-4}$$ 10 - 4 ) W.u. and E2 strengths (several W.u.) between negative- and positive parity bands, particularly for the K"Equation missing" bands decaying to the the K $$^{\pi }=2^+_{\gamma }$$ π = 2 γ + band, consistent with signatures of octupole-quadrupole coupling. In contrast, the K $$^{\pi }=0^-_1$$ π = 0 1 - and K $$^{\pi }=1^-_3$$ π = 1 3 - bands, which exhibit strong E1 transitions to the ground state band, are indicative of octupole-vibrational excitations built on the deformed ground state. Comparison of transition rates with Alaga rules supports this interpretation and distinguishes collective excitations from likely quasi-particle states. These new results establish $$^{162}$$ 162 Dy as the most extensively characterized rare-earth nucleus for negative parity lifetimes and provide critical experimental benchmarks for theoretical models.

Source: The European Physical Journal A

DOI: 10.1140/epja/s10050-026-01806-7