Parity of 57 J=1 levels in 58Ni remains undetermined

Determine the parity, specifically whether electric-dipole (E1) or magnetic-dipole (M1), of the 57 J = 1 excited states in the nucleus 58Ni observed in the 6–13 MeV excitation-energy range, whose multipolarity could not be uniquely identified from forward-angle 295 MeV proton inelastic scattering angular distributions using multipole decomposition analysis, in order to complete the state-by-state dipole-strength mapping.

Background

The paper presents a high-resolution forward-angle 295 MeV (p,p′) experiment on 58Ni, performing a multipole decomposition analysis to extract E1 and M1 character of discrete transitions. In total, 116 dipole transitions were identified; among these, 26 could be uniquely assigned as M1, 11 as E1, and 22 showed a preference for one multipolarity.

However, for 57 transitions with J = 1, the available angular-distribution information was insufficient for a unique multipolarity assignment. This unresolved parity directly impacts the completeness of dipole-strength distributions and their comparison with results from photon scattering (γ,γ′) and electron scattering (e,e′), as well as with shell-model interpretations.