# The structure of 70Fe: Single-particle and collective degrees of freedom

## TL;DR

This paper investigates the excited states of neutron-rich 70Fe using gamma-ray spectroscopy and compares experimental results with shell-model calculations to understand its nuclear structure.

## Contribution

It reports the observation of a new gamma-ray transition in 70Fe and analyzes its implications for the nucleus's single-particle and collective behavior.

## Key findings

- Identification of a new gamma-ray transition feeding the 4+ state.
- Possible assignment of the new gamma ray to the 6+ state based on reaction theory.
- Sensitivity of gamma-ray spectra to lifetimes of 2+ and 4+ states.

## Abstract

Excited states in the neutron-rich \nuc{70}{Fe} nucleus were populated in a one-proton removal reaction from \nuc{71}{Co} projectiles at 87~MeV/nucleon. A new transition was observed with the $\gamma$-ray tracking array GRETINA and shown to feed the previously assigned $4^+_1$ state. In comparison to reaction theory calculations with shell-model spectroscopic factors, it is argued that the new $\gamma$ ray possibly originates from the $6^+_1$ state. It is further shown that the Doppler-reconstructed $\gamma$-ray spectra are sensitive to the very different lifetimes of the $2^+$ and $4^+$ states, enabling their approximate measurement. The emerging structure of \nuc{70}{Fe} is discussed in comparison to LNPS-new large-scale shell-model calculations.