Beta-decay of Mn-65 to Fe-65

TL;DR

This study provides the first detailed level scheme of Fe-65 following Mn-65 beta decay, including precise energy measurements, lifetime data, and comparison with shell-model calculations, revealing a lower beta-delayed neutron emission than previously reported.

Contribution

It establishes the first comprehensive level scheme of Fe-65 post beta-decay of Mn-65, including new lifetime measurements and neutron emission data, with comparison to theoretical models.

Findings

Level scheme of Fe-65 includes 41 levels and 85 transitions.

Beta-delayed neutron emission probability measured at 7.9%.

Four lifetimes in the subnanosecond range were determined.

Abstract

The low energy structure of Fe-65 has been studied by means of gamma- and fast-timing spectroscopy. A level scheme of Fe-65 populated following the beta-decay of Mn-65 was established for the first time. It includes 41 levels and 85 transitions. The excitation energy of the beta-decaying isomer in Fe-65 has been precisely determined at 393.7(2) keV. The beta delayed neutron emission branch was measured as Pn = 7.9(12)%, which cannot be reconciled with the previously reported value of 21.0(5)%. Four gamma-rays and four excited states in Fe-64 were identified as being populated following the beta-n decay. Four lifetimes and five lifetime limits in the subnanosecond range have been measured using the Advanced Time-Delayed Method. The level scheme is compared with shell-model calculations. Tentative spin and parity assignments are proposed based on the observed transition rates, the calculations and the systematics of the region.