Determination of through-going tracks' direction by means of δ-rays in the ICARUS liquid argon time projection chamber

We exploited the crossing muon data, collected in the 50 l liquid argon TPC exposed at the CERN neutrino beam in 1997, to investigate the possibility of identitying the direction of minimum ionizing particle tracks relying only on δ-rays orientation. In this note we show that simple selection criteria allow using δ-rays down to very low energy (few MeV) with high efficiency and no misidentification of their direction. The Monte Carlo prediction - two recognized δ-rays per meter of track - is very well matched by the result of the scanning of the experimental data.