  We report the characterization of correlated photon pairs generated in
dispersion-engineered silicon slow-light photonic crystal waveguides pumped by
picosecond pulses. We found that taking advantage of the 15 nm flat-band
slow-light window (vg ~ c/30) the bandwidth for correlated photon-pair
generation in 96 and 196 \mum long waveguides was at least 11.2 nm; while a 396
\mum long waveguide reduced the bandwidth to 8 nm (only half of the slow-light
bandwidth due to the increased impact of phase matching in a longer waveguide).
The key metrics for a photon-pair source: coincidence to accidental ratio (CAR)
and pair brightness were measured to be a maximum 33 at a pair generation rate
of 0.004 pair per pulse in a 196 \mum long waveguide. Within the measurement
errors the maximum CAR achieved in 96, 196 and 396 \mum long waveguides is
constant. The noise analysis shows that detector dark counts, leaked pump
light, linear and nonlinear losses, multiple pair generation and detector
jitter are the limiting factors to the CAR performance of the sources.
