Precision Test of the Isobaric Multiplet Mass Equation in the A = 32, T = 2 Quintet

Masses of the radionuclides $^{32,33}$Si and $^{34}$P and of the stable nuclide $^{32}$S have been measured with the Low Energy Beam and Ion Trap (LEBIT) Penning trap mass spectrometer. Relative mass uncertainties of 3 x 10$^{-8}$ and better have been achieved. The measured mass value of $^{32}$Si differs from the literature value [1,2] by four standard deviations. The precise mass determination of $^{32}$Si and $^{32}$S have been employed to test the isobaric multiplet mass equation for the A = 32, T= 2 isospin quintet. The experimental results indicate a significant deviation from the quadratic form. This work has been supported by Michigan State University, the NSF under contract number PHY- 0606007, and the DOE under the contract DE-FG02-00ER41144. References: 1. G. Audi, A.H. Wapstra, and C. Thibault, Nucl. Phys. A729 (2003) 337 2. A. Paul, S. R\"{o}ttger, A. Zimbal, and U. Keyser, Hyperfine Interact. 132 (2001) 189