LARGE-BASIS NO-CORE SHELL-MODEL CALCULATIONS AND THEIR APPLICATION TOC-10-]B-10 FERMI BETA-DECAY

We use a 4 (h) over bar Omega shell-model calculation with a two-body effective interaction derived microscopically from the Reid93 potentia l to calculate the isospin-mixing correction for the C-10 --> B-10 sup erallowed Fermi transition. The effective interaction takes into accou nt the Coulomb potential as well as the charge dependence of T = 1 par tial waves. Our results suggest the isospin-mixing correction delta c approximate to 0.1%, which is compatible with previous calculations ob tained by other methods. The obtained delta(C) correction is about a f actor of four too small to obtain unitarity of the Cabibbo-Kobayashi-M askawa matrix with the present experimental data.