Friesen, TimothyWoosaree, Pooja Devi2025-01-092025-01-092025-01-08Woosaree, P. D. (2025). First measurement of antihydrogen free fall using a radial time projection chamber (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.https://hdl.handle.net/1880/120414Using antihydrogen, an apparatus known as ALPHA-g was designed to test Einstein's Weak Equivalence Principle (WEP), where the acceleration due to gravity that a body experiences is independent of its structure or composition. A measurement of the gravitational mass of antimatter has never been done before, as previous experiments used charged particles, which meant the experiments were dominated by electromagnetic forces. The ALPHA-g apparatus uses electrically neutral antihydrogen atoms produced in a vertical Penning-Malmberg trap and trapped in a magnetic minimum trap. By measuring the antihydrogen annihilation positions after a controlled magnetic release of the atoms, the gravitational mass of antihydrogen can be determined. Annihilation positions are reconstructed using a radial time projection chamber (rTPC) surrounding the trapping volume. ALPHA-g was used to complete a successful run in 2022 in the pursuit of measuring the gravitational mass of antihydrogen. The results of this experiment are discussed in this thesis To accurately determine vertical annihilation positions used in the gravity measurement, precise detector calibrations are needed. A laser calibration system was developed and used to gather drift time data in the rTPC, which resulted in drift time measurements and the Lorentz displacement, both of which were used in vertex reconstruction analyses to accurately determine the antihydrogen annihilation positions. Simulations were used to determine the expected electron drift time and Lorentz displacement. Using a Garfield++ toolkit, these observables were simulated from electrons drifting through the gas portion of the ALPHA-g rTPC. Further improvements were made to the reconstruction software to optimise the detector resolution and the number of reconstructed vertices. These methods ultimately led to a free fall direction experiment that concluded antihydrogen fell down on Earth. The experiment was also used to make a preliminary measurement on the gravitational acceleration of a_g = (0:75+/-0:13(statistical + systematic)+/-0:16(simulation))g, where g = 9:81 m/s^2 [1]. Further precision measurements are underway using ALPHA-g to precisely determine the gravitational mass of antihydrogen. Measuring the free-fall direction and gravitational mass of antihydrogen leads the way to a better understanding of the fundamental symmetries in nature, such as the matter-antimatter asymmetry.enUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.AntihydrogenTime Projection ChamberAntimatterTesting Fundamental SymmetriesWeak Equivalence PrincipleVertex ReconstructionsLaser CalibrationNeutral Atom TrappingTrack ReconstructionsPhysics--AtomicPhysics--NuclearElementary Particles and High Energydoctoral thesis