Silicon detector testing for neutron beta decay experiment nab

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Date
2023-08-24
Authors
Macsai, Nicholas
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Abstract
The Standard Model of Particle Physics is a successful yet incomplete description of matter and interactions in the universe. The rate of neutron beta decay in the decay of free neutrons is sensitive to beyond the standard model physics where the types of interactions are constrained by the Lorentz invariance of bi-linear covariants. Precision measurements of decay correlation parameters can be used to test standard model predictions. The Nab experiment at the spallation neutron source(SNS) Oakridge National Laboratory aims to measure the anti-electron-neutrino correlation \lq a\rq, and Fierz interference term \lq b\rq\:in unpolarized neutron decay to greater precision to date. The Nab collaboration uses large area silicon detectors to measure decay products in free neutron decay. Systematic tests of detector system properties are necessary for any precision detection system. The University of Manitoba group modified the Manitoba 2 mass spectrometer to operate as a low energy proton source to use as a detector test facility for low energy protons. The full Nab detector apparatus was installed and tested at the University of Manitoba in early 2021. The subject of this thesis is the preparation of the Manitoba 2 proton source for detector testing and, the operation and characterization of the Nab detector for 30 keV energy protons. In this work, the corresponding setup, tests and partial measurement results are presented. The measured proton energy in general may depend on detector temperature, radial location of detector pixel and the detector bias current, all of which were investigated. The proton energy was measured for three different accelerating potentials (25 KV, 30 KV, 35 KV). The proton event rate was measured in neighbouring pixel during the proton beam sweep across the pixel boundary.
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Keywords
neutron beta decay, low energy proton source, low energy proton detection with silicon detector
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