Detecting neutrinos in IceCube with Cherenkov light in the South Pole ice

The IceCube Neutrino Observatory detects GeV-to-PeV+ neutrinos via the Cherenkov light produced by secondary charged particles from neutrino interactions with the South Pole ice. The detector consists of over 5000 spherical Digital Optical Modules (DOM), each deployed with a single downward-facing photomultiplier tube (PMT) and arrayed across 86 strings over a cubic-kilometer. IceCube has measured the astrophysical neutrino flux, searched for their origins, and constrained neutrino oscillation parameters and cross sections. These were made possible by an in-depth characterization of the glacial ice, which has been refined over time, and novel approaches in reconstructions that utilize fast approximations of Cherenkov yield expectations. After over a decade of nearly continuous IceCube operation, the next generation of neutrino telescopes at the South Pole are taking shape. The IceCube Upgrade will add seven additional strings in a dense infill configuration. Multi-PMT OMs will be attached to each string, along with improved calibration devices and new sensor prototypes. Its denser OM and string spacing will extend sensitivity to lower neutrino energies and further constrain neutrino oscillation parameters. The calibration goals of the Upgrade will help guide the design and construction of IceCube Gen2, which will increase the effective volume by nearly an order of magnitude.Comment: 5 pages, 5 figures, proceeding from the 11th International Workshop on Ring Imaging Cherenkov Detectors (RICH2022

A binned likelihood for stochastic models

Metrics of model goodness-of-fit, model comparison, and model parameter estimation are the main categories of statistical problems in science. Bayesian and frequentist methods that address these questions often rely on a likelihood function, which is the key ingredient in order to assess the plausibility of model parameters given observed data. In some complex systems or experimental setups, predicting the outcome of a model cannot be done analytically, and Monte Carlo techniques are used. In this paper, we present a new analytic likelihood that takes into account Monte Carlo uncertainties, appropriate for use in the large and small sample size limits. Our formulation performs better than semi-analytic methods, prevents strong claims on biased statements, and provides improved coverage properties compared to available methods.Comment: 18 pages, 7 figures, 2 tables, code can be found at https://github.com/austinschneider/MCLL

An improved infrastructure for the IceCube realtime system

The IceCube realtime alert system has been operating since 2016. It provides prompt alerts on high-energy neutrino events to the astroparticle physics community. The localization regions for the incoming direction of neutrinos are published through NASA's Gamma-ray Coordinate Network (GCN). The IceCube realtime system consists of infrastructure dedicated to the selection of alert events, the reconstruction of their topology and arrival direction, the calculation of directional uncertainty contours and the distribution of the event information through public alert networks. Using a message-based workflow management system, a dedicated software (SkyDriver) provides a representational state transfer (REST) interface to parallelized reconstruction algorithms. In this contribution, we outline the improvements of the internal infrastructure of the IceCube realtime system that aims to streamline the internal handling of neutrino events, their distribution to the SkyDriver interface, the collection of the reconstruction results as well as their conversion into human- and machine-readable alerts to be publicly distributed through different alert networks. An approach for the long-term storage and cataloging of alert events according to findability, accessibility, interoperability and reusability (FAIR) principles is outlined.Comment: Presented at the 38th International Cosmic Ray Conference (ICRC2023). See arXiv:2307.13047 for all IceCube contributions. 8 pages, 3 figure

IceCube SkyDriver – A SaaS Solution for Event Reconstruction using the Skymap Scanner

The IceCube Neutrino Observatory is a cubic kilometer neutrino telescope located at the geographic South Pole. To accurately and promptly reconstruct the arrival direction of candidate neutrino events for Multi-Messenger Astrophysics use cases, IceCube employs Skymap Scanner workflows managed by the SkyDriver service. The Skymap Scanner performs maximum-likelihood tests on individual pixels generated from the Hierarchical Equal Area isoLatitude Pixelation (HEALPix) algorithm. Each test is computationally independent, which allows for massive parallelization. This workload is distributed using the Event Workflow Management System (EWMS)—a message-based workflow management system designed to scale to trillions of pixels per day. SkyDriver orchestrates multiple distinct Skymap Scanner workflows behind a REST interface, providing an easy-to-use reconstruction service for real-time candidate, cataloged, and simulated events. Here, we outline the SkyDriver service technique and the initial development of EWMS