  Precision measurements of vector and tensor analyzing powers of the $^{2}{\rm
H}(\vec d,dp){n}$ break-up process for configurations in the vicinity of the
quasi-free scattering regime with the neutron as spectator, are presented.
These measurements are performed with a polarized deuteron-beam with an energy
of 65 MeV/nucleon impinging on a liquid-deuterium target. The experiment was
conducted at the AGOR facility at KVI using the BINA 4$\pi$-detection system.
Events for which the final-state deuteron and proton are coplanar have been
analyzed and the data have been sorted for various momenta of the missing
neutron. In the limit of vanishing neutron momentum and at large
deuteron-proton momentum transfer, the data agree well with the measured and
theoretically predicted spin observables of the elastic deuteron-proton
scattering process. The agreement deteriorates rapidly with increasing neutron
momentum and/or decreasing momentum transfer from the deuteron beam to the
outgoing proton. This study reveals the presence of a significant contribution
of final-state interactions even at very small neutron momenta.
