M. Torti

ICARUS at FNAL

The INFN and the ICARUS collaboration originally developed the technology of the LAr-TPC. Located the underground LNGS Hall-B, the ICARUS T600 detector has been performed over three years with remarkable detection efficiency featuring a smooth operation, high live time, and high reliability. About 3000 CNGS neutrino events have been collected and are being actively analyzed. ICARUS will now be moved to CERN for an extensive RD the T150 will be located at ~150 m. The T600 will also receive >10^4 nu_e events/year from the off-axis NUMI beam peaked around 1 GeV and exploitable to prepare for the LBNE experiment. The ICARUS teams are also interested in extending the participation to other short baseline neutrino activities collaborating with existing FNAL groups.

Experimental observation of an extremely high electron lifetime with the ICARUS-T600 LAr-TPC

The ICARUS T600 detector, the largest liquid Argon Time Projection Chamber (LAr-TPC) realized after many years of R&D activities, was installed and successfully operated for 3 years at the INFN Gran Sasso underground Laboratory. One of the most important issues was the need of an extremely low residual electronegative impurity content in the liquid Argon, in order to transport the free electrons created by ionizing particles with very small attenuation along the drift path. The solutions adopted for the Argon recirculation and purification systems have permitted to reach impressive results in terms of Argon purity and a free electron lifetime exceeding 15 ms, corresponding to about 20 parts per trillion of O2-equivalent contamination, a milestone for any future project involving LAr-TPCs and the development of higher detector mass scales.

The trigger system of the ICARUS experiment for the CNGS beam

The ICARUS T600 detector, with its 470 tons of active mass, is the largest liquid Argon TPC ever built. Operated for three years in the LNGS underground laboratory, it has collected thousands of CNGS neutrino beam interactions and cosmic ray events with energy spanning from tens of MeV to tens of GeV, with a trigger system based on scintillation light, charge signal on TPC wires and time information (for beam related events only). The performance of trigger system in terms of efficiency, background and live-time as a function of the event energy for the CNGS data taking is presented.

Operation and performance of the ICARUS T600 cryogenic plant at Gran Sasso underground Laboratory

ICARUS T600 liquid argon time projection chamber is the first large mass electronic detector of a new generation able to combine the imaging capabilities of the old bubble chambers with the excellent calorimetric energy measurement. After the three months demonstration run on surface in Pavia during 2001, the T600 cryogenic plant was significantly revised, in terms of reliability and safety, in view of its long-term operation in an underground environment. The T600 detector was activated in Hall B of the INFN Gran Sasso Laboratory during Spring 2010, where it was operated without interruption for about three years, taking data exposed to the CERN to Gran Sasso long baseline neutrino beam and cosmic rays. In this paper the T600 cryogenic plant is described in detail together with the commissioning procedures that lead to the successful operation of the detector shortly after the end of the filling with liquid Argon. Overall plant performance and stability during the long-term underground operation are discussed. Finally, the decommissioning procedures, carried out about six months after the end of the CNGS neutrino beam operation, are reported.

Muon momentum measurement in ICARUS-T600 LAr-TPC via multiple scattering in few-GeV range

The measurement of muon momentum by Multiple Coulomb Scattering is a crucial ingredient to the reconstruction of νμ CC events in the ICARUS-T600 liquid argon TPC in absence of magnetic field, as in the search for sterile neutrinos at Fermilab where ICARUS will be exposed to ~ 1 GeV Booster neutrino beam. A sample of ~ 1000 stopping muons produced by charged current interactions of CNGS νμ in the surrounding rock at the INFN Gran Sasso underground Laboratory provides an ideal benchmark in the few-GeV range since their momentum can be directly and independently obtained by the calorimetric measurement. Stopping muon momentum in the 0.5–4.5 GeV/c range has been reconstructed via Multiple Coulomb Scattering with resolution ranging from 10 to 25% depending on muon energy, track length and uniformity of the electric field in the drift volume.