2022 Theses Doctoral

A Search for Axion-like Particles at the Coherent CAPTAIN Mills Experiment

Dunton, Edward C.

While the standard model is enormously successful and internally self consistent, it does not explain a great number of phenomena and is far from a complete theory of particle interactions. Among these missing pieces are a particle theory of dark matter and the Strong CP problem in Quantum Chromodynamics (QCD). A hypothetical axion-like particle (ALP) is a prospective solution to both problems and can be searched for at accelerator produced beam dump experiments.

Neutrino detectors can be used for such a search, due to the similar energy regimes and interactions channels of such detections. The Coherent CAPTAIN Mills (CCM) experiment at the Los Alamos Neutron Science Center (LANCSE) has carried out a search for these ALPs across a number of theoretical models, including dark sector variants and the light QCD axion. An initial run with 120 photomultiplier tubes (PMTs) was used to identify 95\% confidence limits placed across parameter space using an engineering run, which identified several paths to improvement for a longer term search to probe the majority of theoretically motivated parameter space.