Accepted Monday Oct 26, 2009
Masses of the radionuclides 32,33Si and 34P and of the stable nuclides 32S and 31P have been measured with the Low Energy Beam and Ion Trap (LEBIT) Penning trap mass spectrometer. Relative mass uncertainties as low as 3 ×10-9 have been achieved. The measured mass value of 32Si differs from the literature value by four standard deviations. The precise mass determination of 32Si and 32S have been employed to test the validity of the quadratic form of the isobaric multiplet mass equation (IMME) for the most well known A = 32, T = 2 isospin quintet. The new experimental results indicate a dramatic breakdown of the model.