  In this note we discuss the effect of the unpolarized state in the
spin-correlation measurement of the $^1S_0$ two-proton state produced in
12C(d,2He) reaction at the KVI, Groningen. We show that in the presence of the
unpolarized state the maximal violation of the CHSH-Bell inequality is lower
than the classical limit if the purity of the state is less than $ \sim
\verb+70%+$. In particular, for the KVI experiment the violation of the
CHSH-Bell inequality should be corrected by a factor $\sim\verb+10%+$ from the
pure $^1S_0$ state.
