Development and Measurement of an in-situ UV Calibration Device to Measure the Properties of Ultraviolet Light in the South Pole Ice

Unter dem geografischen Südpol liegt das IceCube Neutrino Observatorium. Es nutzt einen Kubikkilometer Gletschereis, um Sekundärteilchen aus Neutrinointerkationen zu detektieren. Der Detektor besteht aus insgesamt 5160 optischen Sensoren, die das Cherenkov Licht der relativistischen, geladenen Teilchen messen. Um die Sensitivität und das Detektionsvermögen zu erhöhen sind Vergrößerungen des Detektors mit neuentwickelten optischen Sensoren geplant. Mindestens einer dieser neuen Sensoren soll den Messbereich aus dem optischen Bereich in den UV Bereich erweitern, wobei eine neu entwickelte wellenlängenschiebende Technologie verwendet wird. Um die Verbesserungen dieser neuen Module zu verstehen, wurde ein Kalibrierungsgerät gebaut, getestet und zweimal bei einer in-situ Messung am geografischen Südpol verwendet. Die Messung wurde in dem offenen SPICEcore borehole durchgeführt. In dem Kalibrierungsgerät waren sowohl Lichtquelle, als auch Detektor verbaut. Um die Eiseigenschaften zu vermessen, wurde Licht in möglichst kurzen Pulsen in das Eis gestrahlt. Der Detektor hat nun die Zeitverteilung gemessen, mit der die Photonen wieder zu dem Detektor zurückgestreut werden. Zur Detektion nutzt das Kalibrierungsgerät die gleiche wellenlängenschiebende Technologie, wie die neuentwickelten optischen Module. Die Messung wurde für Wellenlängen zwischen 245 nm und 400 nm an mehreren Tiefen in einem Bereich, in dem auch IceCube liegt durchgeführt. Diese in-situ Messungen sind der erste erfolgreiche Einsatz der neuen wellenlängenschiebenden Technologie. Mit einem likelihood fit wurde die Messung mit einer Simulation verglichen, welche die Absorption und Streuung der Photonen im Eis als Parameter variiert. Mit dieser Analyse konnte für jede Wellenlänge und Tiefe am besten passende Parameter mit Unsicherheiten, bestehend aus statistischen und systematischen Fehlern gefunden werden. Der größte Einfluss auf die Unsicherheiten ist die schlechte Zeitauflösung des Detektors. Die Ergebnisse legen eine hohe Transparenz im tiefen UV-Bereich nahe und erlauben einen tieferen Einblick in die Streuprozesse im antarktischen Eis.The IceCube Neutrino Observatory lies under the South Pole. It instruments one cubic kilometer of glacial ice to detect secondary particles originating from neutrino interactions. The detector consists of 5160 optical sensors, which measure the Cherenkov light of these relativistic, charged particles. In order to increase the sensitivity and detection range, new extensions with newly developed optical sensors are planned. At least one of these new sensors is supposed to expand the detection range from the optical into the UV range, using a new wavelength shifting technology. To understand the improvements of these new modules, the UV calibration device was built, tested, and deployed twice in in-situ measurements at the geographic South Pole. The measurement was carried out in the open SPICEcore borehole. A light source and a detector were included in the design of the UV calibration device. To measure the ice properties, the light was pulsed in the ice as short as possible. The detector measured the timing distribution of the light getting scattered back. For the detection, the wavelength shifting technology developed for the new optical sensors is used. The measurement was carried out with four wavelengths between 245 nm and 400 nm at several depths, some within the IceCube range. These in-situ measurements successfully applied the new wavelength shifting technology for the first time. Using a likelihood fit, the measurements were compared to a simulation, which varied the absorption and scattering coefficients of the photons in the ice as parameters. With this analysis, a best-fitting set of parameters could be found for each wavelength and depth. The uncertainties are very conservative, consisting of statistical and systematic errors. The most significant influence on the uncertainties is caused by the insufficient time resolution of the detection system. The results suggest a high transparency for the deep UV range and provide a deeper insight into the scattering processes of Antarctic ice

Neutrino interferometry for high-precision tests of Lorentz symmetry with IceCube

We acknowledge the support from the following agencies: USA—US National Science Foundation–Office of Polar Programs, US National Science Foundation–Physics Division, Wisconsin Alumni Research Foundation, Center for High Throughput Computing (CHTC) at the University of Wisconsin–Madison, Open Science Grid (OSG), Extreme Science and Engineering Discovery Environment (XSEDE), US Department of Energy–National Energy Research Scientific Computing Center, Particle astrophysics research computing centre at the University of Maryland, Institute for Cyber-Enabled Research at Michigan State University and Astroparticle physics computational facility at Marquette University; Belgium—Funds for Scientific Research (FRS-FNRS and FWO), FWO Odysseus and Big Science programmes, and Belgian Federal Science Policy Office (Belspo); Germany—Bundesministerium für Bildung und Forschung (BMBF), Deutsche Forschungsgemeinschaft (DFG), Helmholtz Alliance for Astroparticle Physics (HAP), Initiative and Networking Fund of the Helmholtz Association, Deutsches Elektronen Synchrotron (DESY), and High Performance Computing cluster of the RWTH Aachen; Sweden—Swedish Research Council, Swedish Polar Research Secretariat, Swedish National Infrastructure for Computing (SNIC), and Knut and Alice Wallenberg Foundation; Australia—Australian Research Council; Canada—Natural Sciences and Engineering Research Council of Canada, Calcul Québec, Compute Ontario, Canada Foundation for Innovation, WestGrid and Compute Canada; Denmark—Villum Fonden, Danish National Research Foundation (DNRF); New Zealand—Marsden Fund; Japan—Japan Society for Promotion of Science (JSPS) and Institute for Global Prominent Research (IGPR) of Chiba University; Korea—National Research Foundation of Korea (NRF); Switzerland—Swiss National Science Foundation (SNSF); UK—Science and Technology Facilities Council (STFC) and The Royal Society

Non-standard neutrino interactions in IceCube

Non-standard neutrino interactions (NSI) may arise in various types of new physics. Their existence would change the potential that atmospheric neutrinos encounter when traversing Earth matter and hence alter their oscillation behavior. This imprint on coherent neutrino forward scattering can be probed using high-statistics neutrino experiments such as IceCube and its low-energy extension, DeepCore. Both provide extensive data samples that include all neutrino flavors, with oscillation baselines between tens of kilometers and the diameter of the Earth. DeepCore event energies reach from a few GeV up to the order of 100 GeV - which marks the lower threshold for higher energy IceCube atmospheric samples, ranging up to 10 TeV. In DeepCore data, the large sample size and energy range allow us to consider not only flavor-violating and flavor-nonuniversal NSI in the μ−τ sector, but also those involving electron flavor. The effective parameterization used in our analyses is independent of the underlying model and the new physics mass scale. In this way, competitive limits on several NSI parameters have been set in the past. The 8 years of data available now result in significantly improved sensitivities. This improvement stems not only from the increase in statistics but also from substantial improvement in the treatment of systematic uncertainties, background rejection and event reconstruction