  Exclusive and kinematically complete high-statistics measurements of
quasifree polarized $\vec{n}p$ scattering have been performed in the energy
region of the narrow resonance structure $d^*$ with $I(J^P) = 0(3^+)$, $M
\approx$ 2380 MeV/$c^2$ and $\Gamma \approx$ 70 MeV observed recently in the
double-pionic fusion channels $pn \to d\pi^0\pi^0$ and $pn \to d\pi^+\pi^-$.
The experiment was carried out with the WASA detector setup at COSY having a
polarized deuteron beam impinged on the hydrogen pellet target and utilizing
the quasifree process $\vec{d}p \to np + p_{spectator}$. That way the $np$
analyzing power $A_y$ was measured over a large angular range. The obtained
$A_y$ angular distributions deviate systematically from the current SAID SP07
NN partial-wave solution. Incorporating the new $A_y$ data into the SAID
analysis produces a pole in the $^3D_3 - ^3G_3$ waves as expected from the
$d^*$ resonance hypothesis.
