Studies of triggering and exotic particle searches at ATLAS, and a search for trapped monopoles

Sammanfattning: The ATLAS detector at the LHC operated through 2011 and 2012 with 7 and 8 TeV centre-of-mass energy of its colliding proton bunches, respectively. One if its main objectives is to search for physics beyond the Standard Model. This thesis presents a study of a data-driven background method designed for long-lived heavy particles searches, where the signatures are allowed by for example R-parity violating Supersymmetry. Several studies of the perfor- mance of ATLAS trigger system have also been carried out. A contribution to a non-ATLAS search for primordial trapped magnetic monopoles was also undertaken. Data-taking and calibration of a SQUID magnetometer used when searching for magnetic monopoles in volcanic polar rocks were carried out.