Exploring Isospin Symmetry Breaking in Exotic Nuclei: High-Precision Mass Measurement of 23Si and Shell-Model Calculations of T = 5/2 Nuclei
F. M. Maier🇺🇸 · G. Bollen🇺🇸 · B. A. Brown🇺🇸 · S. E. Campbell🇺🇸 · X. Chen🇨🇳 · H. Erington🇺🇸 · N. D. Gamage🇺🇸 · C. M. Ireland🇺🇸 · R. Ringle🇺🇸 · S. Schwarz🇺🇸 · C. S. Sumithrarachchi🇺🇸 · A. C. C. Villari
We present a high-precision mass measurement of the proton-rich nucleus 23Si, performed with the LEBIT Penning trap at the Facility for Rare Isotope Beams (FRIB) utilizing the time-of-flight ion cyclotron resonance (TOF-ICR) technique. We determined a mass excess of 23362.9(5.8) keV, which agrees with a recent storage-ring measurement from CSRe but has a factor 20 improved precision. 23Si is hence the nucleus with the most precisely known mass of all nuclei with an isospin projection of Tz =-5/2. We performed shell-model calculations with the USDC and USDCm Hamiltonians to study binding energy differences and Thomas-Ehrmann shifts in mirror systems with an isospin up to T = 5/2. Our experimental result and other recently reported masses of neutron-deficient sd-shell nuclei agree well with the theoretical predictions, demonstrating that isospin symmetry breaking in sd-shell nuclei, even at high isospin values, is well described by modern shell-model calculations.