Weak interaction rates involving 12 C

and t6 are the isospin raising and lowering single-particle operators. Two main proposals were made to explain this puzzling quenching of the GT strength; ~1! the missing strength is removed to the very high excitation energy of about 300 MeV above the ground state due to the process in which a nucleon is transformed into a D33 resonance, or more precisely the GT strength is removed due to the interaction with the DN (D-nucleon hole! configuration; ~2! the missing GT strength is depleted by short-range correlations and moved to an excitation energy of up to 100 MeV above the main peak. Of course a combination of the two scenarios is also a possibility. Recent (p ,n) experiments in heavy nuclei @3# favor the second possibility, but these have to be supported by additional studies before the resolution of the missing strength puzzle can be established fully. Analysis of GT transition and isoscalar magnetic moment data in the sd shell @4# indicates that the quenching factor in the GT matrix element is given approximately by g5(12dc.m. 2dD), where dc.m.50.16 is the contribution from higherorder configuration mixing and dD50.08 is the contribution from D33 admixtures. The GT strength is reduced by the factor g50.58. In addition to the b decay, other weak processes may probe the quenching of GT strength (L50) or more generally the spin-isospin strength for multipolarity L. Among such weak processes are the m capture and the chargedcurrent ~CC! neutrino scattering on nuclei. In the present