The Fisher–Bingham distribution (
FB
8
) is an eight-parameter family of probability density functions (PDF) on the unit sphere that, under certain conditions, reduce to spherical analogues of ...bivariate normal PDFs. Due to difficulties in its interpretation and estimation, applications have been mainly restricted to subclasses of
FB
8
, such as the Kent (
FB
5
) or von Mises–Fisher (vMF) distributions. However, these subclasses often do not adequately describe directional data that are not symmetric along great circles. The normalizing constant of
FB
8
can be numerically integrated, and recently Kume and Sei showed that it can be computed using an adjusted holonomic gradient method. Both approaches, however, can be computationally expensive. In this paper, I show that the normalization of
FB
8
can be expressed as an infinite sum consisting of hypergeometric functions, similar to that of the
FB
5
. This allows the normalization to be computed under summation with adequate stopping conditions. I then fit the
FB
8
to two datasets using a maximum-likelihood approach and show its improvements over a fit with the more restrictive
FB
5
distribution.
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. This is made possible by an in-depth characterization of the glacial ice, which has been refined over time, and novel approaches in reconstruction 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.
Instrumenting a gigaton of ice at the geographic South Pole, the IceCube Neutrino Observatory has been at the forefront of groundbreaking scientific discoveries over the past decade. These include ...the observation of a flux of TeV-PeV astrophysical neutrinos, detection of the first astrophysical neutrino on the Glashow resonance and evidence of the blazar TXS 0506+056 as the first known astronomical source of high-energy neutrinos. Several questions, however, remain, pertaining to the precise origins of astrophysical neutrinos, their production mechanisms at the source and in Earth’s atmosphere and in the context of physics beyond the Standard Model. This proceeding highlights some of our latest results, from new constraints on neutrino interactions and oscillations to the latest measurements of the astrophysical neutrino flux and searches for their origins to future prospects with IceCube-Gen2.
Neutrino telescopes can observe neutrino interactions starting at GeV energies by sampling a small fraction of the Cherenkov radiation produced by charged secondary particles. These experiments ...instrument volumes massive enough to collect substantial samples of neutrinos up to the TeV scale as well as small samples at the PeV scale. This unique ability of neutrino telescopes has been exploited to study the properties of neutrino interactions across energies that cannot be accessed with man-made beams. Here, we present the methods and results obtained by IceCube, the most mature neutrino telescope in operation, and offer a glimpse of what the future holds in this field.
Many neutrino interactions measured by the IceCube Neutrino Observatory produce only hadronic showers, which appear as almost point-like light emission due to the large detector spacing (125 m). At ...PeV energies these showers often saturate the PMTs closest to the interaction vertex - thus the reconstruction has to rely on more diffused photons which requires precise understanding of the optical properties of the Antarctic ice. Muons produced in the hadronic showers carry information about the neutrino direction, and their Cherenkov light arrives earlier than the photons emitted by the electromagnetic component. A new reconstruction method has been developed which explicitly takes into account the muonic component of hadronic showers and is shown to be robust against systematic ice uncertainties. By applying the new reconstruction, the angular resolution of multi-PeV cascade events can be significantly improved. This will potentially enable follow-up studies of the highest-energy cascade events measured by IceCube.
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.
Abstract
While the Standard Model has experienced great predictive success, the neutrino sector still holds opportunities for surprises. Numerous ongoing and planned experiments exist to probe ...neutrino properties at low energies. The IceCube Neutrino Observatory, comprised of over 5000 photomultiplier tubes (PMTs) situated in a cubic-kilometer of ice at the geographic South Pole, lies in a unique position to measure neutrinos at energies of a TeV and higher. In these proceedings, I discuss several exciting particle physics measurements using IceCube data and probes of physics beyond the Standard Model.
Astrophysical neutrinos are excellent probes of astroparticle physics and high-energy physics. With energies far beyond solar, supernovae, atmospheric, and accelerator neutrinos, high-energy and ...ultra-high-energy neutrinos probe fundamental physics from the TeV scale to the EeV scale and beyond. They are sensitive to physics both within and beyond the Standard Model through their production mechanisms and in their propagation over cosmological distances. They carry unique information about their extreme non-thermal sources by giving insight into regions that are opaque to electromagnetic radiation. This white paper describes the opportunities astrophysical neutrino observations offer for astrophysics and high-energy physics, today and in coming years.
The Fisher-Bingham distribution (\(\mathrm{FB}_8\)) is an eight-parameter family of probability density functions (PDF) on \(S^2\) that, under certain conditions, reduce to spherical analogues of ...bivariate normal PDFs. Due to difficulties in computing its overall normalization constant, applications have been mainly restricted to subclasses of \(\mathrm{FB}_8\), such as the Kent (\(\mathrm{FB}_5\)) or von Mises-Fisher (vMF) distributions. However, these subclasses often do not adequately describe directional data that are not symmetric along great circles. The normalizing constant of \(\mathrm{FB}_8\) can be numerically integrated, and recently Kume and Sei showed that it can be computed using an adjusted holonomic gradient method. Both approaches, however, can be computationally expensive. In this paper, I show that the normalization of \(\mathrm{FB}_8\) can be expressed as an infinite sum consisting of hypergeometric functions, similar to that of the \(\mathrm{FB}_5\). This allows the normalization to be computed under summation with adequate stopping conditions. I then fit the \(\mathrm{FB}_8\) to a synthetic dataset using a maximum-likelihood approach and show its improvements over a fit with the more restrictive \(\mathrm{FB}_5\) distribution.
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