Probing isospin symmetry in the (⁵⁰Fe, ⁵⁰Mn, ⁵⁰Cr) isobaric triplet via electromagnetic transition rates

Lifetimes of the T = 1 isobaric analog I^π = 2⁺ states in ⁵⁰Mn and ⁵⁰Cr have been measured simultaneously by employing the recoil distance Doppler-shift (RDDS) technique. The states were populated in a fusion-evaporation reaction with a ¹²C beam on a ⁴⁰Ca target. An analysis of the data and the calculations from the present work, together with the available B(E2:2⁺→0⁺) data of the isobaric analog states in ⁵⁰Fe and ⁵⁰Cr, have been used to study isospin symmetry in the three A = 50 isobaric nuclei. Shell-model calculations reproduce the magnitudes as well as the increasing trend of the B(E2) data with increasing Z. In order to draw a firm conclusion on the level of isospin mixing in the triplet, a new precision measurement of the 2⁺→0⁺ transition rate in ⁵⁰Fe will be required.