Observation of Singly Charged Barium Ions in a Buffer Gas: Towards a Functional Barium-Tagging System for Use in the Enriched Xenon Observatory

Abstract

The observation of the rare neutrinoless-double-beta-decay will have major implications for both neutrino physics and particle physics as a whole. In particular, a positive observation will conrm the Majorana nature of the neutrino and demonstrate that lepton number is not a strictly conserved quantity. Furthermore, a measurement of the half-life of the decay will lend itself to a measurement of the absolute mass scale of the neutrino. In this work, the sensitivity to observing the neutrinoless-double-beta-decay of 136 Xe is analyzed for the EXO experiment, and the benets of the inclusion of a barium-tagging system in a future tonne-scale detector are demonstrated. In addition, the sensitivity to single barium ion identication is analyzed for two dierent methods of observation: continuous excitation and intermodulation. The intermodulation technique was determined to be the more sensitive as single barium ions were observed with a relatively high signal-to-noise ratio of ∼4 for a one second observation time. Single ions were not observed using the continuous excitation technique.

Background Reduction for Improved Sensitivity at the Enriched Xenon Observatory through advancements in Barium-Tagging Simulations, Prediction and Prevention of High-Voltage Breakdown in Liquid Xenon Time-Projection Chambers, and Event Classification using Ensemble Methods and Machine Learning

“…Using the Feldman-Cousins prescription [20] for estimating the upper limit on the total number of recorded signal events in the ROI, the sensitivity is defined by the value of (the upper limit the number of signal events observed) such that, 0.5 = ( = ′ + | , ) In practice, b, is not known exactly but is also estimated. This produces additional uncertainties in the calculation of (3.0.1), the intricacies of which are described elsewhere [21] [22].…”

A Study Of The Xenon Vapour Pressure Isotope Effect

“…The electron, proton and photon were only three subatomic particles known at that time, and the continuous energy in beta decay spectrum was interpreted as serious issues with the law of conservation of energy [15]. Initially, to explain this condition, some argument was made that in the beta decay of an X atomic nucleus emits an electron eand converted to the nucleus of a different element Y [16],…”

“…The conclusion of Fermi's theory is that the shape of the decay spectrum, especially near the Q value which is different between mass-energy of initial and final particles in a nuclear decay and at high energy depends upon the neutrino's mass [16]. Thus, Fermi explained that either the neutrino has zero mass or very small mass as compared to the mass of an electron.…”