  Polarized small-angle neutron scattering (PSANS) experimental results
obtained on arrays of ferromagnetic Co nanowires ($\phi\approx13$ nm) embedded
in self-organized alumina (Al$_{2}$O$_{3}$) porous matrices are reported. The
triangular array of aligned nanowires is investigated as a function of the
external magnetic field with a view to determine experimentally the real space
magnetization $\vec{M}(\vec{r})$ distribution inside the material during the
magnetic hysteresis cycle. The observation of field-dependentSANSintensities
allows us to characterize the influence of magnetostatic fields. The PSANS
experimental data are compared to magnetostatic simulations. These results
evidence that PSANS is a technique able to address real-space magnetization
distributions in nanostructured magnetic systems. We show that beyond
structural information (shape of the objects, two-dimensional organization)
already accessible with nonpolarized SANS, using polarized neutrons as the
incident beam provides information on the magnetic form factor and stray fields
\textgreek{m}0Hd distribution in between nanowires.
