Study of possible Supersymmetric processes and Mini Black Hole production and comparison to background events with high transverse energy in the ATLAS experiment

The ATLAS detector, which was installed at one of the interaction points of the Large Hadron Collider (LHC), has the capability to discover 'new physics' beyond the Standard Model (SM) already during its first year of operation. In this work an assessment of ATLAS capabilities regarding the detection of some 'new physics' signals is performed. In the course of this research all relevant SM background sources were produced. These sources were studied with several simulation tools and the results are compared. In the scope of these background studies, a verification procedure that relies on expected SM production rates was developed. This procedure is able to distinguish between new physics and a faked one originating in malfunctioning detector. Supersymmetry (SUSY) is one of the best candidates for the theory 'beyond the Standard Model'. It predicts the existence of new symmetry between bosons and fermions, and assumes a new fermion partner for each SM boson and a new boson partner for each SM fermion. A major part of the present research is the study of different SUSY scenarios and their SM background. The study is done both at the phenomenological level and at the experimental level, where ATLAS capabilities to detect the signals are assessed. A special emphasis was made on R-Parity Violating (RPV) processes, which might not manifest themselves immediately like the R-Parity Conserving (RPC) case, which is much easier to detect. Two main categories of RPV signals were studied: supersymmetric particles production through RPC process and their subsequent decay through RPV coupling, and resonating supersymmetric particle creation. Two specific resonating scenarios are studied here for the first time. Analysis methods for the various RPV signals were developed and ATLAS sensitivity was estimated. In addition, a special scenario in the RPV framework that behaves like RPC ("fake RPC") was studied. One will have to take this scenario into consideration if SUSY RPC signal is found in a certain region of the SUSY parameter space. Another possibility of physics 'beyond the SM' is the hypothesis that more dimensions exist in nature and that gravity is the only force that can propagate through them. Such scenario may lead to the production of Mini Black Holes (MBH) at the LHC. MBH are expected to decay through Hawking radiation after a very short time. The final state of such a signal will include many high-PT objects, and should be easy to detect. New particles, such as Weakly Interacting Massive Particle (WIMP), might be copiously produced in the MBH decay process. It is therefore, proposed here to search for new particles among MBH decay products. A preliminary assessment of ATLAS's sensitivity to WIMP production via MBH decays is carried out. The TGC detectors, that were designed and produced mainly by the Weizmann Institute, are used both to trigger events containing energetic muons in the forward direction, and to measure their second coordinate. The Read Out Drivers (RODs) of the TGC detectors, which were also designed and constructed at the Weizmann Institute, are used to collect the information from the TGC detectors. A transmitter that is intended to check the ROD and verify its proper operation was designed as part of this research.