Searches for Magnetic Monopoles and Highly Ionising Particles at 13 TeV at the LHC with MoEDAL
Creators: Bin Akber Ali, Ameir Shaa
Publisher: name: University of Alberta Library
Year: 2023

<p>The standard model of particle physics describes the experimental data collected to date remarkably well. However, this theory (the standard model of particle physics) does not provide a complete description of reality. 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.</p>

<p>Built in a $27 \si{km}$ tunnel at CERN in Geneva, Switzerland, the Large Hadron Collider (LHC) accelerated and collided beams of protons with a center of mass energy of $13 \si{TeV}$ (with a luminosity of $6.46 \si{fb}^{-1}$ at Interaction Point 8) in 2018. These high impact collisions enable us to study the structure of matter at its fundamental. In particular, they enable the production of massive particles that were previously inaccessible to us.</p>

<p>In this report, the data of the MoEDAL detectors at the LHC are exploited to search for a certain class of particles whose existence is predicted by certain theories: highly ionizing particles (HIPs) that is to say particles whose lifetime is long enough to leave a trace in the detector along their trajectory.</p>

<p>Although this research is designed to be sensitive to different types of HIPs in a generic way, the discovery or exclusion of particles that carry a fundamental magnetic charge, called magnetic monopoles, is the major objective of this report. The magnetic monopole was postulated by Paul Dirac in 1931 \cite{diracmonopole} as an elegant way to explain quantization of electric charge, among other virtues. One of the results of the Dirac calculations is that the fundamental unit of magnetic charge must correspond to many electrical charge units and the expected signature of a monopole in a detector is therefore a loss of energy by very high ionization along its trajectory. The presence of monopoles is scanned every time a new particle collider is built. With the LHC, we have the opportunity to explore the multi-TeV energy regime for the first time. </p>

<p>In this thesis, new simulations have been developed to emulate and understand the detector response to highly ionizing particles. MoEDAL uses an array of Magnetic Monopole Trappers (MMTs) and Nuclear Track Detectors (NTDs) to trap and track these monopoles respectively and this method is used to distinguish the signals of new physics at the LHC. </p>

<p>With MoEDAL, an unprecedented concept called the monopole trap was designed to specifically look for the magnetic monopoles produced in LHC collisions. The idea is unconventional, but very simple: Aluminum bars placed near an LHC interaction point (in the LHCb experiment cavern at Interaction Point 8) are exposed to collisions before being transported to a Laboratory in Zurich to detect the presence of magnetic charges trapped with a superconducting magnetometer. In a way that is unique, the trapped monopole would be transportable and its properties can be studied in much detail.</p>