Research, carried out in our Department, is focused on physics of elementary particles at the high energy frontier. The primary aim of these studies is to find manifestations of new physics phenomena that may occur in proton-proton and heavy-ion collisions at the highest accelerator energies.    We are participating in the international ATLAS experiment at Large Hadron Collider (LHC) at CERN. The LHC is the world-class accelerator that provides a rich physics potential to be explored by broad international cooperation.    Effective pursuing of this research programme requires huge computing resources which can only be provided by Grid-like projects which integrate computing resources distributed all over the world. Hence we are also actively involved in the project: Worldwide Grid for LHC experiments (WLCG).    One of the main achievements of the ATLAS experiment is the discovery of a new particle consistent with the long searched Higgs boson. This measurement is of highest importance for our understanding of the basic forces holding the whole Universe. Particularly, the Higgs boson explains how some particles can acquire mass. Without particles mass the Universe would not exist. The event display, on right, shows a single proton-proton collision seen by ATLAS with possible Higgs boson produced (H → 4 electrons).