Towards high-pressure noble gaseous detectors for coherent elastic neutrino-nucleus scattering

Abstract

Coherent elastic neutrino-nucleus scattering (CE$\nu$NS) is a dominant low-energy neutrino interaction that remains experimentally challenging due to its weak-scale cross section and the small nuclear recoil energies involved. This thesis explores the scientific motivations and technical feasibility of CE$\nu$NS\ detection, emphasizing the use of diverse neutrino sources -reactor, spallation, and solar- and multiple target materials. The European Spallation Source (ESS) is identified as a particularly promising site, with simulations indicating an optimal signal-to-background ratio achievable with minimal shielding at a location $\sim$24 meters from the tungsten target. Alternative facilities, such as JPARC-MFL, are also evaluated given construction delays at ESS. A significant contribution of this work is the development of a compact, low-cost, 4$\pi$ neutron scatter camera with integrated optical imaging, capable of characterizing neutron backgrounds and localizing sources using advanced discrimination algorithms and neural networks. Additionally, the thesis presents the design and early testing of GanESS, a novel high-pressure noble gas time projection chamber with electroluminescence amplification, optimized for CE$\nu$NS detection using argon, xenon, or krypton. The Gaseous Prototype (GaP) demonstrates a promising energy threshold of 0.42$\pm$0.04 ${\mathrm{keV}}_{\mathrm{ee}}$ at 8.62 bar of argon and stable high-pressure performance. Detailed simulations using Garfield++ and COMSOL provide insights into electroluminescence behavior and threshold estimation, although some non-linear detector responses at low E/p remain unresolved. Overall, this work establishes a robust foundation for CE$\nu$NS studies at spallation sources and advances detection technologies with broader implications for neutrino physics and rare-event searches.

171 pages, revised version. Thesis submitted to the University of the Basque Country in candidacy for the degree of Doctor of Philosophy. Defended October 13, 2025