E0 transition strength in stable Ni isotopes

Abstract

Excited states in 58,60,62 Ni were populated via inelastic proton scattering at the Australian National University as well as via inelastic neutron scattering at the University of Kentucky Accelerator Laboratory. The Super-e electron spectrometer and the CAESAR Compton-suppressed HPGe array were used in complementary experiments to measure conversion coefficients and δ(E2/M 1) mixing ratios, respectively, for a number of 2 + → 2 + transitions. The data obtained were combined with lifetimes and branching ratios to determine E0, M 1, and E2 transition strengths between 2 + states. The E0 transition strengths between 0 + states were measured using internal conversion electron spectroscopy and compare well to previous results from internal pair formation spectroscopy. The E0 transition strengths between the lowest-lying 2 + states were found to be consistently large for the isotopes studied.

A Guided Tour of ab initio Nuclear Many-Body Theory

“…Multiple applications of the EMλ/ Hamiltonians in support of spectroscopy experiments have been published in recent years (see, e.g., [197,[205][206][207][208]…”

Evidence for shape coexistence in 52Cr through conversion-electron and pair-conversion spectroscopy

“…Unfortunately, there is a large uncertainty on the reported E0 strengths in this work due to the uncertainty in the state lifetimes, and the transition branching and mixing ratios. The unprecedented strength in this region (Ca -Ni) [7,8,14,15] is still not understood, and further measurements of both the E0 transition strengths, along with other spectroscopic quantities like mixing ratios, are needed to reduce the uncertainty on the E0 transition strengths and to understand the structure of these nuclei.…”

“…Large E0 strengths have been recently observed in the Ni isotopes (Z = 28) [7,8], but it is unknown if shape coexistence is present in the N = 28 isotones between doubly magic 48 Ca and 56 Ni. Theoretically, shape coexistence has been predicted in the N = 28 isotones [9], resulting from the excitation of a neutron pair across the N = 28 closed neutron shell from the f 7/2 shell into the f p shell.…”

“…In order to resolve these limitations, an experimental campaign investigating these properties of 52 Cr is planned to take place at the University of Kentucky Accelerator Laboratory (UKAL). The inelastic neutron scattering reaction, (n, n ), has been successfully used to measure nuclear lifetimes via the Doppler-shift attenuation method (DSAM) and mixing ratios via angular distributions in the Ni isotopes, which were needed for accurate E0 strength determination [7,8,28].…”

The Heavy Ion Accelerator Facility: Research Achievements and Aspirations

“…More recently, pair spectroscopy has been used to study E0 transitions in relatively low-Z nuclei. Examples are 0 + → 0 + transitions in the N = Z nuclei 24 Mg and 40 Ca, and a systematic study of E0 transition strengths near N = 28 and Z = 28 that is finding that strong E0 transitions occur only in the semimagic isotopes [39][40][41].…”