EffectivegAin thepfshell

We have calculated the Gamow-Teller matrix elements of 64 decays of nuclei in the mass range $A=41-50\mathrm{}$. In all the cases the valence space of the full $\mathrm{pf}$ shell is used. Agreement with the experimental results demands the introduction of an average quenching factor $q=0.744\mathrm{}\pm 0.015$ slightly smaller but statistically compatible with the $\mathrm{sd}$-shell value, thus indicating that the present number is close to the limit for large $A$.