116 research outputs found
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
Running a Pre-Exascale, Geographically Distributed, Multi-Cloud Scientific Simulation
As we approach the Exascale era, it is important to verify that the existing
frameworks and tools will still work at that scale. Moreover, public Cloud
computing has been emerging as a viable solution for both prototyping and
urgent computing. Using the elasticity of the Cloud, we have thus put in place
a pre-exascale HTCondor setup for running a scientific simulation in the Cloud,
with the chosen application being IceCube's photon propagation simulation. I.e.
this was not a purely demonstration run, but it was also used to produce
valuable and much needed scientific results for the IceCube collaboration. In
order to reach the desired scale, we aggregated GPU resources across 8 GPU
models from many geographic regions across Amazon Web Services, Microsoft
Azure, and the Google Cloud Platform. Using this setup, we reached a peak of
over 51k GPUs corresponding to almost 380 PFLOP32s, for a total integrated
compute of about 100k GPU hours. In this paper we provide the description of
the setup, the problems that were discovered and overcome, as well as a short
description of the actual science output of the exercise.Comment: 18 pages, 5 figures, 4 tables, to be published in Proceedings of ISC
High Performance 202
The IceCube Neutrino Observatory V: Future Developments
Proposed enhancements of the IceCube observatory. Submitted papers to the
32nd International Cosmic Ray Conference, Beijing 2011.Comment: Papers submitted by the IceCube Collaboration to the 32nd
International Cosmic Ray Conference, Beijing 2011; part
Improved modeling of in-ice particle showers for IceCube event reconstruction
The IceCube Neutrino Observatory relies on an array of photomultiplier tubes to detect Cherenkov light produced by charged particles in the South Pole ice. IceCube data analyses depend on an in-depth characterization of the glacial ice, and on novel approaches in event reconstruction that utilize fast approximations of photoelectron yields. Here, a more accurate model is derived for event reconstruction that better captures our current knowledge of ice optical properties. When evaluated on a Monte Carlo simulation set, the median angular resolution for in-ice particle showers improves by over a factor of three compared to a reconstruction based on a simplified model of the ice. The most substantial improvement is obtained when including effects of birefringence due to the polycrystalline structure of the ice. When evaluated on data classified as particle showers in the high-energy starting events sample, a significantly improved description of the events is observed
The IceCube Neutrino Observatory Part VI: Ice Properties, Reconstruction and Future Developments
Papers on ice properties, reconstruction and future developments submitted to
the 33nd International Cosmic Ray Conference (Rio de Janeiro 2013) by the
IceCube Collaboration.Comment: 28 pages, 38 figures; Papers submitted to the 33nd International
Cosmic Ray Conference, Rio de Janeiro 2013; version 2 corrects errors in the
author lis
IceCube experience using XRootD-based Origins with GPU workflows in PNRP
The IceCube Neutrino Observatory is a cubic kilometer neutrino telescope
located at the geographic South Pole. Understanding detector systematic effects
is a continuous process. This requires the Monte Carlo simulation to be updated
periodically to quantify potential changes and improvements in science results
with more detailed modeling of the systematic effects. IceCube's largest
systematic effect comes from the optical properties of the ice the detector is
embedded in. Over the last few years there have been considerable improvements
in the understanding of the ice, which require a significant processing
campaign to update the simulation. IceCube normally stores the results in a
central storage system at the University of Wisconsin-Madison, but it ran out
of disk space in 2022. The Prototype National Research Platform (PNRP) project
thus offered to provide both GPU compute and storage capacity to IceCube in
support of this activity. The storage access was provided via XRootD-based OSDF
Origins, a first for IceCube computing. We report on the overall experience
using PNRP resources, with both successes and pain points.Comment: 7 pages, 3 figures, 1 table, To be published in Proceedings of CHEP2
In-situ estimation of ice crystal properties at the South Pole using LED calibration data from the IceCube Neutrino Observatory
The IceCube Neutrino Observatory instruments about 1 km3 of deep, glacial ice at the geographic South Pole using 5160 photomultipliers to detect Cherenkov light emitted by charged relativistic particles. A unexpected light propagation effect observed by the experiment is an anisotropic attenuation, which is aligned with the local flow direction of the ice. Birefringent light propagation has been examined as a possible explanation for this effect. The predictions of a first-principles birefringence model developed for this purpose, in particular curved light trajectories resulting from asymmetric diffusion, provide a qualitatively good match to the main features of the data. This in turn allows us to deduce ice crystal properties. Since the wavelength of the detected light is short compared to the crystal size, these crystal properties do not only include the crystal orientation fabric, but also the average crystal size and shape, as a function of depth. By adding small empirical corrections to this first-principles model, a quantitatively accurate description of the optical properties of the IceCube glacial ice is obtained. In this paper, we present the experimental signature of ice optical anisotropy observed in IceCube LED calibration data, the theory and parametrization of the birefringence effect, the fitting procedures of these parameterizations to experimental data as well as the inferred crystal properties.</p
LeptonInjector and LeptonWeighter: A neutrino event generator and weighter for neutrino observatories
We present a high-energy neutrino event generator, called LeptonInjector,
alongside an event weighter, called LeptonWeighter. Both are designed for
large-volume Cherenkov neutrino telescopes such as IceCube. The neutrino event
generator allows for quick and flexible simulation of neutrino events within
and around the detector volume, and implements the leading Standard Model
neutrino interaction processes relevant for neutrino observatories:
neutrino-nucleon deep-inelastic scattering and neutrino-electron annihilation.
In this paper, we discuss the event generation algorithm, the weighting
algorithm, and the main functions of the publicly available code, with
examples.Comment: 28 pages, 10 figures, 3 table
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