We present comparison studies between Geant4 shower packages and ATLAS Tile Calorimeter test-beam data collected at CERN in H8 beam line at the SPS. Emphasis is put on hadronic physics lists and data concerning differences between Tilecal response to pions and protons of same energy. The ratio between the pure hadronic fraction of pion and the pure hadronic fraction of proton F^h_pi/F^h_p was estimated with Tilecal test-beam data and compared with

The sensitivity of the ATLAS experiment to extra dimensions, excited quarks and leptons, new gauge bosons, charged heavy leptons, lepton flavour violation and strong symmetry breaking is discussed. Finally, a brief summary of the extended potential of an upgraded LHC will be presented.

The sensitivity of the ATLAS experiment to charged heavy leptons and excited lectrons is discussed. The accessible limits for the mass of these heavy leptons in the ATLAS detector are presented.

The analysis of the data collected by the NA50 experiment in 1998, reported in this paper, extends and clarifies the pattern of the previously observed J/Psi; anomalous suppression. This new measurement, besides providing a deeper understanding of the previous observations, reveals a steady significative decrease in the J/Psi; production rate up to the most central Pb-Pb collisions. It clearly rules out the presently available conventional (hadronic)