ATLAS Experiment

One of the excellent examples of the scientific and technological cooperation of the researchers from Georgia, with European Union countries is the participation of the physicists of High Energy Physics Institute of Iv. Javakhishvili Tbilisi State University (HEPI TSU) in the ATLAS experiment at the Large Hadron Collider (LHC) of European Organization for Nuclear Research (CERN, Geneva, Switzerland). The ATLAS (A Toroidal LHC ApparatuS) experiment at CERN laboratory in Geneva uses state of art instruments to explore the outer reaches of our understanding of the universe. ATLAS is one of the four major experiments at the Large Hadron Collider (LHC) at CERN. ATLAS brings experimental physicists into new territory. Most exciting is the completely unknown – new processes and particles that would change our understanding of energy and matter. Among the possible unknowns are extra dimensions of space, unification of fundamental forces, and string theory. Already ATLAS has discovered the Higgs boson, the source of mass for fundamental particles. ATLAS will learn about the basic forces that have shaped our Universe since the beginning of time and will determine its fate.

To investigate the fundamental processes of nature at the Large Hadron Collider, the ATLAS scientists had to design a detector of unprecedented size and complexity. The 46 m long and 25 m high ATLAS detector is one of the most elaborate particle physics experiments ever designed and is the product of a world-wide effort by over 5000 scientists from 180 universities and laboratories in 38 countries, working in close collaboration with industry to find solutions to the extraordinary challenges of data taking at the LHC at CERN. ATLAS is observing and recording the products of head-on collisions of accelerated protons at energies that may rich to 13 TeV. In the coming years it is planned to increase the energy of collisions up to 14 TeV. Almost 1200 doctoral students are involved in detector development, data collection and analyses.

Georgian Physicists from High Energy Physics Institute of Iv. Javakhishvili Tbilisi State University participated in ATLAS experiment since 1994 from the early stages of experiment preparation. The leader of the team “Tbilisi” was Prof. Jemal Khubua from 1994 up to 2017, from 2017 – becomed Dr. Irakli Minashvili. Team “Tbilisi” incorporates High Energy Physics Institute of I.Javakhishvili Tbilisi State University, E. Andronikashvili Institute of Physics and Georgian Technical University Nuclear Engineering Center.

The physicists from HEPI TSU (Jemal Khubua, Irakli Minashvili and Nugzar Mosulihvili) along with scientists from Czech Republic and Greece participated in the design, construction, installation, commissioning at the cavern and electronics refurbishment of Hadronic Tile Calorimeter of ATLAS detector, in preparation and performance of combined set-up (Liquid Argon electromagnetic and hadronic Tile Calorimeters modules) test beams using pion and electron beams of energy 10-350 GeV, analysis of test beam data (T.Djobava, M.Mosidze). Georgian Physicists studied the ATLAS experiment sensitivity to Flavour Changing Neutral Currents (FCNC) physics induced rare decays of top quark (L. Chikovani, T. Djobava, M. Mosidze). HEPI TSU physicists are co-participants of the one of the most greatest discovery of 21-th century in particle physics – observation of Higgs boson at ATLAS experiment. On 4 July 2012, the ATLAS and CMS experiments at CERN announced that they had independently observed a new particle, consistent with the Higgs boson. The result of the discovery has been published in international scientific journal Physics Letters as two independent papers (Phys.Lett. B716, 1 (2012) – ATLAS results; Phys.Lett. B716, 30 (2012) –CMS results). The project participants (Prof. J. Khubua, I. Minashvili, T. Djobava, M. Mosidze) are co-authors of one of these papers. Theorists Francois Englert and Peter Higgs who predicted the existence of the Higgs boson in the Standard Model of particle physics, were awarded the Nobel Prize in Physics in 2013. The Higgs boson is now being used as an instrument by physicists to explore for new physics in the high energy collisions of the LHC.