β -decay feeding intensity distribution of Mn64

Nuclei around the $N=40$ ``island of inversion'' exhibit interesting structure features that have been the focus of several experimental and theoretical studies. The present work presents the first complete study of the β-decay feeding intensity distribution and Gamow-Teller distribution for the β decay of ⁶⁴Mn to ⁶⁴Fe up to ≈10 MeV. The β-decay intensity function was extracted from total absorption spectroscopy measurements made at the National Superconducting Cyclotron Laboratory with the Summing NaI(Tl) (SuN) detector. The experimental results are compared to shell model calculations with and without the inclusion of the νg9/2 orbital. From this comparison it is clear that the νg9/2 orbital is essential for the accurate description of the ⁶⁴Fe4pt0exβ-decay strength above ≈3 MeV, emphasizing once again the transitional nature of this nucleus into the $N=40$ island of inversion.