A comprehensive search for “anomalies” from neutrino and anti-neutrino oscillations at large mass differences (Δm^2 ~ 1eV^2) with two LAr–TPC imaging detectors at different distances from the CERN-PS.

The present proposal describes an experimental search of sterile neutrinos beyond the Standard Model with the CERN-PS beam and the innovative technology of imaging in ultra-pure cryogenic liquid Argon. The proposal is based on two strictly identical LAr-TPC detectors observing the electron-neutrino signal in the ”Far” and “Near” positions, the first one of about 600 tons placed 850 m the second one of about 150 tons at about 6.5 times shorter distance from the proton target. This project will exploit the ICARUS T600 — now running in the underground experiment CNGS2 with neutrinos from the CERN-SPS — moved from GranSasso to the CERN “Far” position. The additional T150 will be constructed and located in the “Near” position. In the two positions, the radial and energy spectra of the nu_e beam are practically identical. Comparing the two detectors, in absence of oscillations, all cross sections and experimental biases cancel out and the two experimentally observed event distributions must be identical. Any difference of the event distributions at the locations of the two detectors might be attributed to the possible existence of neutrino oscillations, presumably due to additional neutrinos with a new mixing angle and a larger mass difference. Two main anomalies will be explored with both neutrino and anti-neutrino focused beams. According to the first anomaly some of the nu_e (anti-nu_e) and/or nu_mu (anti-nu_mu) events might be converted into invisible components, leading to observation of oscillatory, distance dependent disappearance rates. In a second anomaly (following LSND and MiniBooNE observations) some distance dependent oscillations may be observed as a excess, especially in the antineutrino channel. A total LAr mass of 760 + 200 ton and a reasonable utilization of the CERN-PS with the refurbished TT7 beam line will offer remarkable discovery potentialities, collecting a very large number of unbiased events both in the neutrino and antineutrino channels, largely adequate to definitely settle the origin of the many indications behind the -related anomalies.