BEGIN:VCALENDAR VERSION:2.0 CALSCALE:GREGORIAN PRODID:UW-Madison-Physics-Events BEGIN:VEVENT SEQUENCE:0 UID:UW-Physics-Event-9544 DTSTART:20260108T200000Z DTEND:20260108T220000Z DTSTAMP:20260405T100738Z LAST-MODIFIED:20251229T202125Z LOCATION:B343 Sterling SUMMARY:Improved Techniques for the Determination of the Neutrino Mass Ordering with IceCube1 DeepCore and the IceCube Upgrade\, Thesis Defe nse\, Joshua Henry Peterson\, Physics PhD Graduate Student DESCRIPTION:The electrons in Earth's matter affect the oscillation of atmospheric neutrinos and antineutrinos differently depending on the n eutrino mass ordering. As more neutrinos than antineutrinos are expect ed to be detected in the IceCube Neutrino Observatory\, this matter ef fect can be used to probe the NMO. The fraction of energy transferred to the nucleon during a neutrino interaction\, known as the inelastici ty\, has a different distribution for neutrinos and antineutrinos. Thi s can in theory be used to statistically separate neutrinos from antin eutrinos\, but hasn't been exploited in IceCube DeepCore or the upcomi ng IceCube Upgrade. Processing photomultiplier tube voltage waveforms from detections of photons is a computationally intensive process that needs to be done before any science can proceed. We explore methods t o port this process into the digital optical modules of future IceCube expansions\, and find multiple ways to increase the speed of the wave form processing. The processed photon information can then be used for neural network reconstructions. New two dimensional convolutional neu ral networks are developed for neutrino flavor identification and inel asticity reconstruction in IceCube DeepCore\, which outperform other c onvolutional neural network algorithms. Model stacking methods with bo osted decision trees are developed to combine neural network algorithm s for further improve performance. We also developed a graph neural ne twork for inelasticity reconstruction for the IceCube Upgrade. The ine lasticity reconstructions are then used as a fourth observable\, along with the particle energy\, direction and neutrino flavor\, to calcula te new neutrino mass ordering sensitivities and determine the impact o f adding the inelasticity in the measurement of the neutrino mass orde ring with IceCube DeepCore and upcoming IceCube Upgrade detectors. It is found that incorporating inelasticity improves the sensitivity to t he neutrino mass ordering for both DeepCore and the Upgrade\, for both the normal and inverted orderings\, especially for the normal orderin g in the second octant of $\\theta_{23}$. We also find that small impr ovements to the current IceCube Upgrade inelasticity reconstruction ca n lead to significant increases in the sensitivity to the neutrino mas s ordering.
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\n URL:https://www.physics.wisc.edu/events/?id=9544 END:VEVENT END:VCALENDAR