GiantM1states in Zr isotopes within the simple shell model

The newly observed $M1\mathrm{}$ states in the ($p$,$p^{\prime }$) experiment on the Zr isotopes are considered within the simple shell model. The calculation with a constant strength $\delta$ function interaction reproduces the excitation energies and the slight increase of the $M1\mathrm{}$ strength at small momentum transfer with mass number. We need about a factor of 2 quenching to reproduce the cross sections at small angles, which is in accordance with the general finding for magnetic transitions.