  The total cross sections are important ingredients for the current and future
neutrino oscillation experiments. We present measurements of the total
charged-current neutrino and antineutrino cross sections on scintillator (CH)
in the NuMI low-energy beamline using an {\em in situ} prediction of the shape
of the flux as a function of neutrino energy from 2--50 GeV. This flux
prediction takes advantage of the fact that neutrino and antineutrino
interactions with low nuclear recoil energy ($\nu$) have a nearly constant
cross section as a function of incident neutrino energy. This measurement is
the lowest energy application of the low-$\nu$ flux technique, the first time
it has been used in the NuMI antineutrino beam configuration, and demonstrates
that the technique is applicable to future neutrino beams operating at
multi-GeV energies. The cross section measurements presented are the most
precise measurements to date below 5 GeV.
