  The vortex line density of turbulent superfluid He3-B at very low temperature
is deduced by detecting the shadow of ballistic quasiparticles which are
Andreev reflected by quantized vortices. Until now the measured total shadow
has been interpreted as the sum of shadows arising from interactions of a
single quasiparticle with a single vortex. By integrating numerically the
quasi-classical Hamiltonian equations of motion of ballistic quasiparticles in
the presence of nontrivial but relatively simple vortex systems (such as
vortex-vortex and vortex-antivortex pairs and small clusters of vortices) we
show that partial screening can take place, and the total shadow is not
necessarily the sum of the shadows. We have also found that it is possible
that, upon impinging on complex vortex configurations, quasiparticles
experience multiple reflections, which can be classical, Andreev, or both.
