  We calculate differential cross sections and the spin transfer coefficient
$D_{nn}$ in the $\vec{p}+\alpha \to \vec{p}+\alpha+\pi^0$ reaction for proton
bombarding energies from 1 to 10 GeV and $\pi^0 - p$ invariant masses spanning
the region of the N$^*$(1440) Roper resonance. Two processes -- $\Delta$
excitation in the $\alpha$-particle and Roper excitation in the proton -- are
included in an effective reaction model which was shown previously to reproduce
existing inclusive spectra. The present calculations demonstrate that these two
contributions can be clearly distinguished via $D_{nn}$, even under kinematic
conditions where cross sections alone exhibit no clear peak structure due to
the excitation of the Roper.
