  We show that the dynamical freezing of vortex structures nucleated at diluted
densities in Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8}$ samples with a dense
distribution of columnar defects, $B \sim 10^{-2} B_{\Phi}$ with
$B_{\Phi}=5$\,kG, results in configurations with liquid-like correlations. We
propose a freezing model considering a relaxation dynamics dominated by
double-kink excitations driven by the local stresses obtained directly from
experimental images. With this model we estimate the relaxation barrier and the
freezing temperature. We argue that the low-field frozen vortex structures
nucleated in a dense distribution of columnar defects thus correspond to an
out-of-equilibrium non-entangled liquid with strongly reduced mobility rather
than to a snapshot of a metastable state with divergent activation barriers as
for instance expected for the Bose-glass phase at equilibrium.
