Precise measurement of photomultiplier tube non-linearity for the MOLLER Experiment

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dc.contributor.authorGunawardhana, Anuradha
dc.contributor.examiningcommitteeRodgers, Jessica (Physics and Astronomy)
dc.contributor.examiningcommitteeGericke, Michael (Physics and Astronomy)
dc.contributor.supervisorLongo, Savino
dc.date.accessioned2025-04-21T20:15:45Z
dc.date.available2025-04-21T20:15:45Z
dc.date.issued2025-03-25
dc.date.submitted2025-03-25T15:41:48Zen_US
dc.degree.disciplinePhysics and Astronomy
dc.degree.levelMaster of Science (M.Sc.)
dc.description.abstractThe MOLLER (Measurement of a Lepton-Lepton Electroweak Reaction) experiment is an international collaboration formed to achieve unprecedented precision in measuring the parity-violating asymmetry in electron-electron scattering to probe the weak mixing angle, and to explore potential physics beyond the Standard Model. A critical component of this measurement is the use of photomultiplier tubes (PMTs) operating in integration mode within the main detector array. Accurate characterization of PMT non-linearity is essential to minimize systematic uncertainties. This study develops and validates a robust methodology for measuring the non-linearity of PMTs under conditions replicating those of the MOLLER experiment. A novel bench-top apparatus integrating UV-LED light sources, optical chopper, neutral density (ND) filters and a light diffuser was designed to generate controlled light signals mimicking the experimental environment. Automation techniques were leveraged heavily when implementing the data collection to efficiently evaluate over 300 PMTs while achieving the stringent MOLLER's PMT non-linearity precision goal of ±0.1%. The results demonstrate that PMT non-linearity (differential) remains below the critical threshold of 0.5%, confirming their suitability for the MOLLER experiment. These findings provide confidence in the integrity of the detector system and ensure the precision required for the measurement of parity-violating asymmetry. Beyond its immediate application, this study contributes to the broader field of experimental particle physics by advancing methods for detector characterization and by setting a benchmark for similar high-precision measurements.
dc.description.noteMay 2025
dc.description.sponsorshipUniversity of Manitoba - Fellowship for Education Purposes
dc.identifier.urihttp://hdl.handle.net/1993/39032
dc.language.isoeng
dc.subjectMOLLER
dc.subjectDetector
dc.subjectPhotomultiplier
dc.subjectPMT
dc.subjectNon-linearity
dc.titlePrecise measurement of photomultiplier tube non-linearity for the MOLLER Experiment
local.subject.manitobano
oaire.awardNumber1752
oaire.awardTitleMaster's Studentship Award
oaire.awardURIhttps://researchmanitoba.ca/funding/programs/masters-studentship-award/
project.funder.identifierhttp://dx.doi.org/10.13039/100008794
project.funder.nameResearch Manitoba
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