We investigate the "low-ν" method (developed by the CCFR/NUTEV
collaborations) to determine the neutrino flux in a wide band neutrino beam at
very low energies, a region of interest to neutrino oscillations experiments.
Events with low hadronic final state energy ν<νcut (of 1, 2 and 5 GeV)
were used by the MINOS collaboration to determine the neutrino flux in their
measurements of neutrino (νμ) and antineutrino (\nub_\mu) total cross
sections. The lowest νμ energy for which the method was used in MINOS is
3.5 GeV, and the lowest \nub_\mu energy is 6 GeV. At these energies, the
cross sections are dominated by inelastic processes. We investigate the
application of the method to determine the neutrino flux for νμ,
\nub_\mu energies as low as 0.7 GeV where the cross sections are dominated by
quasielastic scattering and Δ(1232) resonance production. We find that
the method can be extended to low energies by using νcut values of 0.25
and 0.50 GeV, which is feasible in fully active neutrino detectors such as
MINERvA.Comment: 25 pages, 32 figures, to be published in European Physics Journal