  Hybrid superconductor/graphene (SC/g) junctions are excellent candidates for
investigating correlations between Cooper pairs and quantum Hall (QH) edge
modes. Experimental studies are challenging as Andreev reflections are
extremely sensitive to junction disorder and high magnetic fields are required
to form QH edge states. We fabricated low-resistance SC/g interfaces, composed
of graphene edge contacted with NbN with a barrier strength of $Z\approx 0.4$,
that remain superconducting under magnetic fields larger than $18$ T. We
establish the role of graphene's Dirac band structure on zero-field Andreev
reflections and demonstrate dynamic tunability of the Andreev reflection
spectrum by moving the boundary between specular and retro Andreev reflections
with parallel magnetic fields. Through the application of perpendicular
magnetic fields, we observe an oscillatory suppression of the 2-probe
conductance in the $\nu = 4$ Landau level attributed to the reduced efficiency
of Andreev processes at the NbN/g interface, consistent with theoretical
predictions.
