Measuring the anomalous precession frequency wa for the Muon g − 2 experiment

Abstract

Announced in April 2021, the Run−1 result of the Fermilab Muon g−2 experiment increased the discrepancy between the measured value of the magnetic anomaly of the muon, aμ, and the value predicted by Standard Model theory to over 4σ. A key component of the aμ value is the measurement of the anomalous precession frequency ωa, made possible by the parity-violating nature of the weak decay of muons. The energies of decay positrons carry information about the spin direction of the parent muons, so a suite of 24 calorimeters records the hit times and energies of decay positrons to fit for the oscillation ωa. To perform a precise ωa measurement, the nearly 1300 channels present in the calorimeter system must be aligned both in time and energy scale. In this thesis, the physical hardware of the calorimeter system and the data-processing software will be described; a blinded, preliminary analysis of Run−2 ωa data will be shown, highlighting a possible improvement from the Run − 1 analysis; and some systematic studies related to the detector hardware will be assessed in the context of Run − 1 data.