Revalidation of the isobaric multiplet mass equation at A = 53, T = 3/2

Abstract The T = 3 / 2 isobaricanalog state (IAS) in 53 Co is firmly established through a comprehensive measurement of β -delayed γ and proton decayof 53 Ni. The determined excitation energy of 53 Co IAS combined with the mass of 53 Co generates a precise mass excessof − 38 333.6 ( 27 ) keV for the 53 Co IAS, which is 70(18) keV lower than the previously adopted value. The new result solves a problem raised by incorrect assignments of the 53 Co IAS of unexpected deviation from the isobaric multipletmass equation (IMME) at A = 53 , T = 3 / 2 .