# First spectroscopy of 61Ti and the transition to the Island of Inversion at N = 40

## TL;DR

This study reports the first spectroscopy of 61Ti, revealing new isomeric states and providing evidence for the transition to the Island of Inversion at N=40 through experimental measurements and shell model calculations.

## Contribution

It introduces the first observation of isomeric states in 61Ti and links these findings to the onset of the Island of Inversion at N=40.

## Key findings

- Two new isomeric states in 61Ti observed for the first time.
- Shell model calculations confirm 61Ti's placement within the Island of Inversion.
- Measured lifetimes and transition properties support the particle-hole excitation scenario.

## Abstract

Isomeric states in 59,61Ti have been populated in the projectile fragmentation of a 345 AMeV 238U beam at the Radioactive Isotope Beam Factory. The decay lifetimes and delayed gamma-ray transitions were measured with the EURICA array. Besides the known isomeric state in 59Ti, two isomeric states in 61Ti are observed for the first time. Based on the measured lifetimes, transition multipolarities as well as tentative spins and parities are assigned. Large-scale shell model calculations based on the modified LNPS interaction show that both 59Ti and 61Ti belong to the Island of Inversion at N=40 with ground state configurations dominated by particle-hole excitations to the g_9/2 and d_5/2 orbits.