Analysis of an Antineutrino Detector

Abstract

Reactor neutrinos can be used to monitor a reactor's existence, power level, and isotopic content during burnup, offering unique safeguarding applications. We are building a 650 kg mobile, surface-level antineutrino detector, called CHANDLER. CHANDLER detects antineutrinos through inverse beta decay (IBD), using a highly segmented array of plastic scintillator segments to identify the positron through topology, and sheets of lithium-doped zinc sulfide to cleanly distinguish the neutron using pulse shape discrimination PSD. This dissertation talks about improvements made to the CHANDLER detector based on information gathered from its prototype, MiniCHANDLER, which saw a neutrino signal a commercial reactor at 5.5 σ, but could benefit from a number of upgrades. New optics have higher energy resolution and a new electronics system is not only cheaper per channel, but also allows for more advanced data handling and triggering with its on board freely programmable gate array. Moving from cubical lattice segmentation to half-cube segmentation allowed for more lithiated sheets to be added to the detector, improving both spatial resolution and neutron capture efficiency. This additional segmentation complicates event reconstruction, necessitating the development of new methods that accelerate reconstruction by several or- ders of magnitude and enable in-line corrections for swapping errors and feed-through light. The larger detector can fully contain events enough to leverage the topology of back-to-back positron annihilation gammas. Simulated IBD and background data were supplied to simple machine learning algorithms to produce a 'human-like' analysis that predicts the detector should be capable of seeing 200 IBDs with 200 backgrounds per day at a 40 meter stand off from a commercial reactor, which is sufficient for identification and power-level monitoring capabilities. This dissertation also discusses work done with PALEOCCENE to produce radiation induced color-center tracks in lithium-fluoride crystals, a step towards developing passive coherent elastic neutrino-nucleus scattering detectors.