Experimental study of neutrino interactions with the ArgoNeuT liquid-argon TPC exposed to the NuMI beam

Liquid-Argon Time Projection Chamber (LAr-TPC) technology provides unique features in event imaging and calorimetric resolution. These characteristics, combined with a good rejection power and a (virtually) unlimited active mass, make tins technology one of the best candidates for the next generation of long-baseline neutrino oscillation experiments. The ArgoNeuT detector, a small LAr-TPC (0.24 ton of active mass) exposed to the NuMI beam at Fermilab and currently producing the first low-energy neutrino events in a LAr-TPC, is the first step of a staged US program to realize and operate a massive LAr-TPC detector for v physics. This paper describes design details, experimental goals and current status of the experiment and reports a first example of quasi-elastic nu(mu) charged-current event reconstruction, including a first evidence of nuclear effects in the region surrounding the interaction vertex.