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Title: Measurement of vertical betatron oscillations using the straw tracking detectors for the E989 muon g-2 experiment at Fermilab
Author: Halewood-Leagas, Tabitha
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2019
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The measurement of the anomalous magnetic moment of electrons and muons has been an important test of the Standard Model (SM) of particle physics over many decades. This is because it can be measured experimentally and calculated theoretically to a high precision. In particular the anomalous magnetic moment of the muon, αμ, is an ideal candidate for the search of new physics due to the combination of the muons large mass and relatively long lifetime. The current world's most precise value of αμ was measured by the E821 experiment at the Brookhaven National laboratory (BNL). This achieved a precision of 540 ppb (463 ppb stat., 283 ppb syst.) and measured a ~ 3.5 s deviation from the SM value. This motivated a new experiment: the E989 muon g-2 experiment at the Fermi National Accelerator Laboratory (Fermilab) to confirm or reject this discrepancy. This experiment aims to gather a data sample 21 times larger than the BNL experiment and improve the determination of the systematic uncertainties by a factor of three and thereby achieve a fourfold increase in precision to 140 ppb. If the αμ value were to remain unchanged, this improvement in precision would establish evidence for Beyond SM (BSM) physics with a significance of more than 7 standard deviations. The Fermilab experiment has the same methodology as the BNL experiment and reuses the experiment's storage ring magnet. New, improved experimental apparatus has been introduced to reduce the systematic uncertainty on the αμ measurement. One such improvement is the addition of two straw tracking stations. These measure the trajectory of the positrons emitted from the (positive) muon decays which allows a detailed study of the spatial and temporal motion of the beam and critical crosschecks of the calorimeter data. This thesis describes in detail the design, construction and testing of the tracking detectors which were built at the University of Liverpool. A detailed study of the vertical motion of the beam is also presented. This study provides an important correction that must be applied to the data before αμ can be determined.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral