On the multipole mixing ratio of the $1066$ keV transition from the 0.52 $\mu s$ isomer of $^{180}$Hf

TL;DR

This study measures the multipole mixing ratio of a key gamma transition in $^{180}$Hf, providing refined data crucial for testing nuclear models of this axially symmetric prolate rotor with high-K isomers.

Contribution

The paper presents a more precise measurement of the multipole mixing ratio of the 1066 keV transition and clarifies the spin assignment of the 1374 keV state in $^{180}$Hf.

Findings

Refined multipole mixing ratio of the 1066 keV transition.

Supported the tentative spin assignment of the 1374 keV state as (4^-).

Provided data to constrain nuclear models of $^{180}$Hf.

Abstract

The nucleus $^{180}$Hf is one of the most primary of examples of an axially symmetric prolate rotor. Combined with the presence of high-$K$ isomers, spectroscopic studies can provide important information on the nature of its single-particle levels. Precise measurements are essential for constraining nuclear models and interpreting the nature of such isomeric states. In this work, the nucleus $^{180}$Hf was populated using the proton pick-up reaction $^{181}$Ta($^{11}$B,$^{12}$C)$^{180}$Hf at beam energy of 47 MeV at Horia Hulubei National Institute of Nuclear Physics and Engineering (IFIN-HH). The spin of the 1374 keV state and the mixing ratio of the $1066$ keV transition have been measured, the latter with an increased precision compared to the previous value from literature. The presently measured spin of the 1374 keV state, currently assigned a tentative value of $(4^-_1)$, favors one of the two different values reported in the literature. The particular state constitutes the band-head of a rotational band in $^{180}$Hf. The measured multipolarity mixing ratio of the inter-band transition $1374 \rightarrow 309$ keV can provide important information for the testing and constraining of theoretical nuclear models used for the study of the intrinsic properties of $^{180}$Hf as well as its neighboring isotopes.