OAR@UM Collection:

Stability of the ALICE-HMPID detector in LHC runs 1 and 2 and PID performance in p-Pb collections at energy per nucleon pair of 8.02 TeV

2022-08-23T05:45:34Z

Title: Stability of the ALICE-HMPID detector in LHC runs 1 and 2 and PID performance in p-Pb collections at energy per nucleon pair of 8.02 TeV Abstract: The stability over Runs 1 and 2 and the particle identification (PID) performance in p-Pb collisions at √snn= 8.02 Tev of the High Momentum Particle Identification Detector (HMPID), present in the A Large Ion Collider Experiment (ALICE) at the Large Hadron Collider (LHC) at CERN, were studied. The stability studies involved the analysis of pp collisions, the data of which was obtained in 2018. The analysis updated the already existing studies for Runs 1 and 2. Moreover, an additional study of the ageing of the Csl films of the photocathodes was done. The results obtained, shmv that the detector is stable over the two Run periods. The same cannot be said for Run2, which presents a general decrease in number of photons being detected, particularly for the RICH2 module, where the decrease is extensive. Thus, a more in-depth study of the Run and of the module were performed. On the other hand, the PID performance study involved the analysis of data obtained in pPb collisions at √snn= 8.02 Tev, which data was collected in 2016. This research also involved the stability of the detector during this data taking. Finally, the normalised raw yields of pions, kaons and ( anti-)protons were obtained for different multiplicities in the laboratory rapidity range -0.465 < Ylab < 0.035 for the p-Pb collisions at √snn= 8.02 Tev. The results obtained show that the PID performance of the detector is optimal and that the transverse momentum spectra of the particles present heavy-ion collision like behaviour. Description: B.SC.(HONS)PHYSICS

Single-sided collimation and the effects on beam cleaning and impedance in the LHC

2022-04-13T05:34:18Z

Title: Single-sided collimation and the effects on beam cleaning and impedance in the LHC Abstract: The Large Hadron Collider (LHC) employs a multistage collimation system to protect against unavoidable beam losses during operation. A regular collimator consists of two movable blocks placed symmetrically around the circulating beam in order to intercept halo particles. These blocks are known as jaws and are generally composed of a highly robust material which is designed to withstand extreme levels of temperature, pressure, and radiation. The charged particles travelling inside the accelerator generate electromagnetic fields which interact with the surrounding structure, giving rise to forces that perturb the motion of the beam, often leading to beam degradation. This perturbing effect ultimately determines the performance of the accelerator in terms of beam quality and stored current, and is characterised by the so-called beam-coupling impedance. The collimation system is the single highest contributor to the transverse impedance at top energy. This is because the collimator jaws are the closest elements to the beam, and thus interact more strongly the electromagnetic fields generated by the particles. As the beam intensity increases, so too does the coupling impedance, and when the perturbations become sufficiently strong, the beam becomes unstable. Seeing as the High-Luminosity LHC (HL-LHC) upgrade nearly doubles the bunch population, impedance must be reduced in order to ensure beam stability. Single-sided collimation aims at mitigating impedance by fully retracting one of the two jaws for any number of collimators. One would expect this to come at the cost of beam cleaning; however, simulations have shown that this is not necessarily the case, especially when selecting the right combination of jaws. This thesis explores the feasibility of single-sided collimation for the betatron cleaning insertion in HL-LHC by running simulations that quantify performance in terms of beam cleaning and impedance. Benchmark measurements have also been performed for LHC. Description: M.SC.PHYSICS

The framework of a modular vehicle dynamics simulator

2022-04-04T13:26:51Z

Title: The framework of a modular vehicle dynamics simulator Abstract: The importance of vehicle simulators in the automotive and motorsport industry is ever increasing. Designed to mimic the real life physical system it is meant to model, vehicle simulators can aid engineers in making the best design choices prior to any manufacturing. This project aims to build a modular vehicle simulator capable of containing all the necessary components which influence the handling of the vehicle, with the major components implemented fully and others as placeholders. It will aid in the development of a Formula Student race car and serve as a test bench for different design parameters. The project is built using the Simulink (R) environment uses a 6-degree of freedom platform (normally used to model aircraft) to ensure maximum flexibility. The project includes detailed suspension and tyre models which apply forces to the platform so that the longitudinal and turning dynamics can be investigated. Basic engine and aerodynamic placeholder modules are also implemented so as to be able to get meaningful results which can be compared with those obtained from an instrumented Formula Student race car. Description: M.SC.PHYSICS

Observational constraints in extended teleparallel gravity

2022-03-16T06:06:21Z

Title: Observational constraints in extended teleparallel gravity Abstract: Describing gravity accurately has become one of the lingering problems of modern-day physics. The General Theory of Relativity (GR), as proposed by Einstein, remains the best descriptor we have of the mysterious force, but just like with Newton's theory, GR is running into hurdles that, until now, it cannot overcome. This thesis looks into an alternate formulation of the gravitational theory known as the Teleparallel Equivalent of General Relativity (TEGR) which is equivalent to GR at a background level, and holds promise to provide some sort of explanation towards these problems. Specifically this thesis analyses extensions of TEGR known as f(T) and f(T,B) which seek to provide a deeper explanation towards solving the cosmological constant problem, and attempts to give a better understanding behind the term dark energy. This will be done by constraining cosmological parameters to a few carefully selected models and testing their fit against specific observational data sets in order to examine their performance against the current standard model. Description: B.SC.(HONS)MATHS&PHYSICS