Atmospheric neutrinos in a large Liquid Argon Detector

In view of the evaluation of the physics goals of a large Liquid Argon TPC, evolving from the ICARUS technology, we have studied the possibility of performing precision measurements on atmospheric neutrinos. For this purpose we have improved existing Monte Carlo neutrino event generators based on FLUKA and NUX by including the 3–flavor oscillation formalism and the numerical treatment of Earth matter effects. By means of these tools we have studied the sensitivity in the measurement of θ23 through the accurate measurement of νe’s. The updated values for ∆m 2 23 from Super–Kamiokande and the mixing parameters as obtained by solar and KamLand experiments have been used as reference input, while different values of θ13 have been considered. An exposure larger than 500 kton yr seems necessary in order to achieve a significant result, provided that the present knowledge of systematic uncertainties is largely improved.