Momentum measurement by the multiple Coulomb scattering method in the OPERA lead-emulsion target

A new method of momentum measurement of charged particles
\nthrough multiple Coulomb scattering (MCS) in the OPERA lead-emulsion target
\nis presented. It is based on precise measurements of track angular deviations
\ncarried out thanks to the very high resolution of nuclear emulsions. The
\nalgorithm has been tested with Monte Carlo pions. The results are found to describe within the expected uncertainties the data obtained from test beams.
\nWe also present a comparison of muon momenta evaluated through MCS
\nin the OPERA lead-emulsion target with those determined by the electronic
\ndetectors for neutrino-charged current interaction events. The two independent
\nmeasurements agree within the experimental uncertainties, and the results
\nvalidate the algorithm developed for the emulsion detector of OPERA.