Systematic Studies Of E0 Transitions In 54,56,58 Fe

Abstract

Doubly magic nuclei and their near neighbours serve as an ideal testing ground for the nuclear shell model, and, consequently, enable us to define effective nuclear interactions. Collective states in nuclei near 56 Ni can be attributed to multiparticle-multihole excitations from the 1 f 7/2 to the 2p 3/2 , 1 f 5/2 and 2p 1/2 orbits across the N, Z = 28 shell gap. These features are usually associated with shape coexistence. Properties of excited 0 + states, as well as E0 and E2 transition strengths are sensitive probes of the underlying nuclear structure. The aim of this work is to identify and characterize excited 0 + states and corresponding E0 transitions in 54,56,58 Fe to search for shape coexistence around the N, Z = 28 shell closure. In order to obtain experimental information, E0 transitions between the lowest excited 0 + states and ground states were measured for the stable even-even iron isotopes using the superconducting electron spectrometer ,"Super-e", at the Australian National University. Additional information on angular distributions, angular correlations, and γ − γ coincidences was obtained with the CAESAR detector array (at ANU) under the same experimental conditions. In order to deduce E0 strengths, the experimental data were evaluated with lifetime information from Doppler-shift attenuation measurements following inelastic neutron scattering, carried out at the University of Kentucky.

To Shell Model, or Not to Shell Model, That Is the Question

“…A leading factor is lack of stable targets for multi-nucleon transfer reactions. However, an initiative is underway, with a highresolution internal-pair spectrometer, the Super-e, at the ANU to explore the occurrence of E0 transitions in this mass region [128,129,[233][234][235][236]. However, there is evidence that shape coexistence is present in the N = 28 isotones 54 Fe and 52 Cr from transfer reactions: this is placed in a broad framework in Figure 60.…”

E0 transition strength in stable Ni isotopes

“…The use of this calibration source is also discussed in Ref. [22]. This 170 Lu source is particularly useful in the case of electron detectors as there are few long-lived radionuclides suitable as discrete-energy electron calibration sources, especially at higher electron energies.…”