# A revised $B(E2; 2^+_1 \to 0^+_1)$ value in the semi-magic nucleus $^{210}$Po

## TL;DR

This study measures the lifetime of the first 2+ state in $^{210}$Po, finding it shorter than previous values, but existing models still cannot fully explain its nuclear structure.

## Contribution

The paper provides a revised lifetime measurement for the $2^+_1$ state in $^{210}$Po using Doppler-shift attenuation, challenging current theoretical models.

## Key findings

- Revised lifetime of $2^+_1$ state is about three times shorter than previous values.
- Current shell and Quasi-particle Phonon Models cannot fully explain the nuclear properties.
- The new data suggests a peculiarity in $^{210}$Po's structure not captured by existing theories.

## Abstract

The lifetimes of the $2^+_1$, the $2^+_2$ and the $3^-_1$ states of $^{210}$Po have been measured in the $^{208}$Pb($^{12}$C,$^{10}$Be)$^{210}$Po transfer reaction by the Doppler-shift attenuation method. The results for the lifetime of the $2^+_1$ state is about three times shorter than the adopted value. However, the new value still does not allow for consistent description of the properties of the yrast $2^+_1$, $4^+_1$, $6^+_1$, and $8^+_1$ states of $^{210}$Po in the framework of nuclear shell models. The Quasi-particle Phonon Model (QPM) calculations also cannot overcome this problem thus indicating the existence of a peculiarity which is neglected in both theoretical approaches.