l-forbidden M1 transition in S-32: A test of tensor corrections to the magnetic dipole operator

The extremely weak l-forbidden 1d(3/2) --> 2s(1/2) magnetic dipole (M1) tra nsition from the ground state of S-32 to a J(pi) = 1(+) state at E-x = 7.00 3 MeV was investigated by 165 degrees and 180 degrees electron scattering. The extracted strength of 0.0040(5)mu(N)(2) represents the smallest B(M1)up arrow value ever measured in electron scattering. A combined analysis with the isospin-analogous Gamow-Teller (GT) decays of the J(pi) = 1(+) ground states of Cl-32 and P-32 is performed. Empirical corrections of Brown and W ildenthal to the magnetic operators reasonably account for the data. Correc tions derived from microscopic approaches are less successful pointing towa rds a fundamental, not yet understood problem in the description of the eff ective M1 and GT operators.