BEGIN:VCALENDAR VERSION:2.0 CALSCALE:GREGORIAN PRODID:UW-Madison-Physics-Events BEGIN:VEVENT SEQUENCE:2 UID:UW-Physics-Event-8288 DTSTART:20230614T160000Z DTEND:20230614T180000Z DTSTAMP:20260414T051648Z LAST-MODIFIED:20230530T154501Z LOCATION:4274 Chamberlin and https://uwmadison.zoom.us/j/95946215316?p wd=NU9aSzh6NlZGanF6QkM4THU2cU9Cdz09https://uwmadison.zoom.us/j/9594621 5316?pwd=NU9aSzh6NlZGanF6QkM4THU2cU9Cdz09 SUMMARY:Measurement of the Astrophysical Diffuse Neutrino Flux using S tarting Track Events in IceCube\, Graduate Program Event\, Manuel Silv a\, Department of Physics Graduate Student DESCRIPTION:Since the discovery of cosmic rays by Victor Hess in 1912\ , there have been numerous advances in the field including but not lim ited to: larger cosmic ray detectors\, observatories searching for gam ma-rays and astrophysical neutrinos. This dissertation focuses on neut rinos since they are neutral and light making them the optimal messeng er. By measuring the neutrino flux\, we can better under the mechanism s by which these cosmic rays are created. In 2013\, the IceCube collab oration first announced the observation of these astrophysical neutrin os launching us into the era of high energy neutrino astrophysics. Thi s work summarizes a novel dataset\, searching for starting track event s\, whereas a neutrino interacts within the fiducial volume of the det ector producing a muon track. This event morphology is of particular i mportance as it enables us to measure the energy of the event to withi n 25% error and the direction of the event to within 1.5◦ error. Uti lizing 10.3 years of IceCube data\, we characterize the astrophysical diffuse neutrino flux. Using a single power law flux\, we measure the spectral index as γ = 2.58+0.10−0.09 and the per-flavor normalizati on as ΦAstro per−flavor = 1.68+0.19 −0.22 (at 100 TeV). The sensi tive energy range to this flux is 3-550 TeV making this the lowest ene rgy astrophysical flux measurement to date. We also show structure (or lack thereof) in the flux towards lower energies by using a broken po wer law. We reject γ <\; 1 to 3σ significance and γ <\; 2 to 2. 1σ significance below a break energy of 25 TeV. URL:https://www.physics.wisc.edu/events/?id=8288 END:VEVENT END:VCALENDAR