  MgB2 superconducting wires with critical temperature Tc approaching 40 K were
used for preparation of MgB2/Ag and MgB2/In junctions. The differential
conductance vs. voltage characteristics of N-S junctions exhibit clear
contribution of Andreev reflection. Using modified BTK theory for s-wave
superconductors two order parameters 4 meV and 2.6 meV have been determined
from temperature dependencies. Surprisingly, larger order parameter vanishes at
lower temperature ~20 K than smaller one with Tc 38 K. Both the magnitudes of
the order parameters and their critical temperatures are in good agreement with
theoretical calculations of electron-phonon coupling in MgB$_2$ carried out by
Liu et al.
