Searches for magnetic monopoles and highly ionising particles at 13 TeV at the LHC with MoEDAL

• Main Author: Ameir Shaa
• Other Authors: Chew Lock Yue
• Format: Final Year Project
• Language: English
• Published: 2017
• Subjects: DRNTU::Science
• Online Access: http://hdl.handle.net/10356/72887
• Institution: Nanyang Technological University

The Standard Model of Particle Physics abbreviated as SM describes experimental data to date extremely well. The last puzzle piece of the SM, the Higgs Boson, was found in 2012. However, the SM is unable to describe reality completely as there are many questions left to answer such as: What is dark matter and what is the origin of dark matter? How do we explain the hierarchy between the masses of the elementary particles? Is it possible to describe all the interactions in a coherent way within the same theory? Why is there an asymmetry between electricity and magnetism? Why is there an asymmetry between matter and anti-matter? These are some of the fundamental questions left unanswered by the standard model. Many new physical theories, such as supersymmetry, have been proposed to answer these questions, but they need to be experimentally verified. Experimental verification comes in the form of the Large Hadron Collider housed in a 27-km tunnel at CERN in Geneva, Switzerland. The LHC was built mainly for looking for the Higgs Boson and now that it is found, it concentrates on looking for particles that are the result of theories beyond the SM (BSM). In 2016, the LHC accelerated and collided beams of protons with a center of mass energy of 13 TeV (with a luminosity of 2.28 fb$^{-1}$ at Interaction Point 8). Due to the protons colliding at these massive energies, we are able to then study matter at the fundamental level. It also produces other particles previously inaccessible to us due to the limited energy scale. In this report, we collect data from the detectors of MoEDAL to search for Highly Ionizing Particles (HIPs). HIPs are a certain class of particles whose characteristic is to have a long enough lifetime such that they are able to leave a trace in the detector along their trajectory. In particular, at MoEDAL, we focus on the discovery (or exclusion) of a class of particles that carry a fundamental magnetic charge called magnetic monopoles and further shortened to monopoles. However, we note that the detectors of MoEDAL are not restricted to just the monopole but any HIP and it is just that we focus on a particular subset of the class of HIP (i.e. the monopole). Postulated by Paul Dirac in 1931, the monopole was first derived as an elegant explanation to the quantization of electric charge. Furthermore, Dirac explains that the fundamental unit of magnetic charge, $g_D = 68.5$e. Therefore, it follows that the signature of a monopole is a loss of energy by high ionization along the traversed path. In MoEDAL, an unconventional but simple idea is employed to trap the monopoles. This device called the Magnetic Monopole Trapper (MMT) is an arrray of aluminium bars placed in the LHCb experiment cavern at Interaction Point 8. The MMTs are exposed to p-p collisions before being transported to Zurich where a SQUID is employed to detect the presence of monopoles. The fact that the monopoles are able to be trapped and transported for study is unprecedented.