Study of {\it M1} Quenching in $^{28}$Si by a $p,p'$ Measurement at 0 Deg.

The quenching of $Gammow$-$Teller$($GT$) strengths with respect to the sum rule has been discussed as an opened problem. Similarly the $M1$ strengths may have the some quenching problem because the transition includes the same operator ``$\sigma \tau$'' with the $GT$ one. Since there are two type transitions in $M1$ strengths, $IS$($\Delta T$=0) and $IV$($\Delta T$=1), another aspect of the quenching can be found from their difference. The experiment was carried out at RCNP by applying both ``dispersion-matching technique'' and ``under-focus mode'' for high resolution measurements at 0$^{\circ}$. A 295 MeV unpolarized proton beam bombarded natural Si target. After detailed calibrations, an energy resolution of 20 keV and a scattering angle resolution of 0.5 $\sim$ 0.8$^{\circ}$ were achieved. Background events were subtracted reasonably. In order to select 1$^+$ states, angler distribution of each peak was compared with DWBA calculations. The comparison between the experimental results and theoretical predictions of $IS$ and $IV$ will be discussed.