arXiv subjects

Christian Glaser

Publications and source records attributed to Christian Glaser.

At least 19 recordsLinked to original sources

arXiv2026

What is new in NuRadioMC: Multilayer Analytic Raytracer

NuRadioMC is a framework for the simulation of ultra-high-energy neutrino detectors that measure the radio signal emitted in neutrino-induced particle cascades used in different radio neutrino experiments. We present an extension to the analytic raytracing method for multilayered exponential refractive index models, where the full refractive index profile is described by a set of different single-exponential layers, supporting realistic medium descriptions at various experiment sites while maintaining computational efficiency. This approach also enables a realistic exponential refractive index description of the atmosphere and allows us to model signal propagation over non-smooth changes in the refractive index. This report outlines the fundamentals of the multilayered analytic raytracing method and shows some applied examples.

astro-ph.IM↗

arXiv2026

On the Codesign of Scientific Experiments and Industrial Systems

The optimization of large experiments in fundamental science, such as detectors for subnuclear physics at particle colliders, shares with the optimization of complex systems for industrial or societal applications the common issue of addressing the inter-relation between parameters describing the hardware used in data production and parameters used to analyse those data. While in many cases this coupling can be ignored -- when the problem can be successfully factored into simpler sub-tasks and the latter addressed serially -- there are situations in which that approach fails to converge to the absolute maximum of expected performance, as it results in a mis-alignment of the optimized hardware and software solutions. In this work we consider a few use cases of interest in fundamental science collected primarily from particle physics and related areas, and a pot-pourri of industrial and societal applications where the matter is similarly of relevance. We discuss the emergence of strong hardware-software coupling in some of those systems, as well as co-design procedures that may be deployed to identify the global maximum of their relevant utility functions. We observe how numerous opportunities exist to advance methods and tools for hardware-software co-design optimization, bridging fundamental science and industry through application- and challenge-driven projects, and shaping the future of scientific experiments and industrial systems.

physics.ins-det↗

arXiv2025

Event Reconstruction for Radio-Based In-Ice Neutrino Detectors with Neural Posterior Estimation

The detection of ultra-high-energy (UHE) neutrinos in the EeV range is the goal of current and future in-ice radio arrays at the South Pole and in Greenland. Here, we present a deep neural network that can reconstruct the main neutrino properties of interest from the raw waveforms recorded by the radio antennas: the neutrino direction, the energy of the particle shower induced by the neutrino interaction, and the event topology, thereby estimating the neutrino flavor. For the first time, we predict the full posterior PDF for the energy and direction reconstruction via neural posterior estimation utilizing conditional normalizing flows, enabling event-by-event uncertainty prediction. We improve over previous reconstruction algorithms and obtain a median resolution of 0.30 log(E) and 18 square degrees for a 'shallow' detector component and 0.08 log(E) and 28 square degrees for a 'deep' detector component for neutral current (NC) events at a shower energy of 1 EeV. This deep learning approach also allows us to reconstruct the more stochastic $\nu_e$ - charged current (CC) events. We quantify the impact of different antenna types and systematic uncertainties on the reconstruction and derive a goodness-of-fit score to test the compatibility of measured neutrino signals with the Monte Carlo simulations used to train the neural network.

astro-ph.IM↗

arXiv2025

Likelihood Reconstruction for Radio Detectors of Neutrinos and Cosmic Rays

Ultra-high-energy neutrinos and cosmic rays are excellent probes of astroparticle physics phenomena. For astroparticle physics analyses, robust and accurate reconstruction of signal parameters such as arrival direction and energy is essential. Radio detection is an established detector concept explored by many observatories; however, current reconstruction methods ignore bin-to-bin noise correlations, which limits reconstruction resolution and, so far, has prevented calculations of event-by-event uncertainties. In this work, we present a likelihood description of neutrino or cosmic-ray signals in radio detectors with correlated noise, as present in all neutrino and cosmic-ray radio detectors. We demonstrate, with simulation studies of both neutrinos and cosmic-ray radio signals, that signal parameters such as energy and direction, including event-by-event uncertainties with correct coverage, can be obtained. This method reduces reconstruction uncertainties and biases compared to previous approaches. Additionally, the Likelihood can be used for event selection and enables differentiable end-to-end detector optimization. The reconstruction code is available through the open-source software NuRadioReco.

astro-ph.IM↗

arXiv2025

A Differentiable Surrogate Model for the Generation of Radio Pulses from In-Ice Neutrino Interactions

The planned IceCube-Gen2 radio neutrino detector at the South Pole will enhance the detection of cosmic ultra-high-energy neutrinos. It is crucial to utilize the available time until construction to optimize the detector design. A fully differentiable pipeline, from signal generation to detector response, would allow for the application of gradient descent techniques to explore the parameter space of the detector. In our work, we focus on the aspect of signal generation, and propose a modularized deep learning architecture to generate radio signals from in-ice neutrino interactions conditioned on the shower energy and viewing angle. The model is capable of generating differentiable signals with amplitudes spanning multiple orders of magnitude, as well as consistently producing signals corresponding to the same underlying event for different viewing angles. The modularized approach ensures physical consistency of the samples and leads to advantageous computational properties when using the model as part of a bigger optimization pipeline.

astro-ph.IM↗

arXiv2025

Probing ultra-high-energy neutrinos with the IceCube-Gen2 in-ice radio array

The next generation neutrino telescope, IceCube-Gen2, will be sensitive to the astrophysical and cosmogenic flux of neutrinos across a broad energy range, from the TeV to the EeV scale. The planned design includes 8 cubic kilometers of ice instrumented with approximately 10,000 optical sensors, a surface array, and a radio array of antennas embedded in the ice laid out sparsely over 500 km^2. The radio array provides sensitivity to ultra-high energy neutrinos using independent radio stations that can trigger on Askaryan emission from neutrino interactions in the ice. In this contribution, we present the design for the radio array along with its planned implementation, which is expected to increase sensitivity to neutrinos with energies beyond 100PeV by at least an order of magnitude over existing arrays. Furthermore, we will quantify the expected science output by presenting measurement forecasts for the main science cases of diffuse flux and point source discovery, as well as cross-section and flavor measurements.

astro-ph.HE↗

arXiv2025

In-ice Askaryan Emission from Air Showers: Implications for Radio Neutrino Detectors

One of the most promising techniques for detecting ultra-high energy neutrinos involves the use of radio antennas to observe the 10-1000 MHz radiation generated by the showers that neutrinos induce in large volumes of ice. The expected neutrino detection rates of one neutrino or less per detector station per 10 years make the characterization of backgrounds a priority. The largest natural background comes from ultra-high energy cosmic rays which are orders of magnitude more abundant than neutrinos. Particularly crucial is the understanding of geometries in which substantial energy of the cosmic-ray-induced air shower is deposited in the ice giving rise to a compact in-ice shower close to the ice surface. We calculated the radio emission of air-shower cores using the novel CORSIKA 8 code and found it to be similar to the predictions for neutrino-induced showers. For the first time, we calculated the detection rates for O(100m) deep antennas yielding 10-100 detections per year and detector station, which makes this a useful calibration source as these downward-going signals can be differentiated from neutrino-induced showers based on the signal arrival direction. However, the presence of reflection layers in the ice confuses the arrival directions, which makes this a potentially important background. We review the existing information on reflecting layers in the South Pole glacier and, for the first time, quantify the corresponding rate of reflected air-shower signals for the proposed IceCube-Gen2 radio array and discuss mitigation strategies. The reflectivity of the layers is the dominant uncertainty resulting in rate predictions of much less than one detection to several detections per year for IceCube-Gen2 if not mitigated.

astro-ph.HE↗

arXiv2024

Deep learning reconstruction of neutrino direction, energy, and flavor with complete uncertainty predictions

With the IceCube-Gen2 observatory under development and RNO-G under construction, the first detection of ultra-high-energy neutrinos is on the horizon making event reconstruction a priority. Here, we present a full reconstruction of the neutrino direction, shower energy, and interaction type (and thereby flavor) from raw antenna signals. We use a deep neural network with conditional normalizing-flows for the reconstruction. This, for the first time, allows for event-by-event predictions of the posterior distribution of all reconstructed properties, in particular, the asymmetric uncertainties of the neutrino direction. The algorithm was applied to an extensive MC dataset of 'shallow' and 'deep' detector components in South Pole ice. We present the reconstruction performance and compare the two station components. For the first time, we quantify the effect of birefringence on event reconstruction.

astro-ph.IM↗

arXiv2024

Likelihood reconstruction of radio signals of neutrinos and cosmic rays

Ultra-high-energy neutrinos and cosmic rays are excellent probes of astroparticle physics phenomena. For astroparticle physics analyses, robust and accurate reconstruction of signal parameters like arrival direction and energy is essential. Current reconstruction methods ignore bin-to-bin noise correlations, which limits reconstruction resolution and so far has prevented calculations of event-by-event uncertainties. In this work, we present a likelihood description of neutrino or cosmic-ray signals in a radio detector with correlated noise, as present in all neutrino and cosmic-ray radio detectors. We demonstrate with a toy-model reconstruction that signal parameters such as energy and direction, including event-by-event uncertainties with correct coverage, can be obtained. Additionally, by correctly accounting for correlations, the likelihood description constrains the best-fit parameters better than alternative methods and thus improves experimental reconstruction capabilities.

astro-ph.IM↗

arXiv2024

The flavor composition of ultra-high-energy cosmic neutrinos: measurement forecasts for in-ice radio-based EeV neutrino telescopes

In-ice radio-detection is a promising technique to discover and characterize ultra-high-energy (UHE) neutrinos, with energies above 100 PeV, adopted by present - ARA, ARIANNA, and RNO-G - and planned - IceCube-Gen2. So far, their ability to measure neutrino flavor has remained unexplored. We show and quantify how the neutrino flavor can be measured with in-ice radio detectors using two complementary detection channels. The first channel, sensitive to $ν_e$, identifies them via their charged-current interactions, whose radio emission is elongated in time due to the Landau-Pomeranchuk-Migdal effect. The second channel, sensitive to $ν_μ$ and $ν_τ$, identifies events made up of multiple showers generated by the muons and taus they generate. We show this in state-of-the-art forecasts geared at IceCube-Gen2, for representative choices of the UHE neutrino flux. This newfound sensitivity could allow us to infer the UHE neutrino flavor composition at their sources - and thus the neutrino production mechanism - and to probe UHE neutrino physics.

astro-ph.HE↗

arXiv2023

Atmospheric muons at PeV energies in radio neutrino detectors

Experiments seeking to detect radio emission stemming from neutrino interactions will soon reach sensitivities that bring a detection within reach. Since experiments like RNO-G or the future IceCube-Gen2 target more than an order of magnitude more effective volume than existing experiments, the renewed and detailed study of rare backgrounds is needed. In this paper, we study the potential background from energy losses of highly energetic atmospheric muons. Due to both limited experimental measurements and limited modeling in hadronic interaction models, the expected event rate is subject to large uncertainties. Here, we estimate rate predictions and their uncertainties for different models and instrumental parameters. We also study possible routes towards mitigation of the muon background, such as parent air shower detection, and illustrate what is needed to make the first measurement of the prompt muon flux at energies above 10 PeV.

astro-ph.HE↗

arXiv2023

Deep Learning Based Event Reconstruction for the IceCube-Gen2 Radio Detector

The planned in-ice radio array of IceCube-Gen2 at the South Pole will provide unprecedented sensitivity to ultra-high-energy (UHE) neutrinos in the EeV range. The ability of the detector to measure the neutrino's energy and direction is of crucial importance. This contribution presents an end-to-end reconstruction of both of these quantities for both detector components of the hybrid radio array ('shallow' and 'deep') using deep neural networks (DNNs). We are able to predict the neutrino's direction and energy precisely for all event topologies, including the electron neutrino charged-current interactions, which are more complex due to the LPM effect. This highlights the advantages of DNNs for modeling the complex correlations in radio detector data, thereby enabling a measurement of the neutrino energy and direction. We discuss how we can use normalizing flows to predict the PDF for each individual event which allows modeling the complex non-Gaussian uncertainty contours of the reconstructed neutrino direction. Finally, we discuss how this work can be used to further optimize the detector layout to improve its reconstruction performance.

astro-ph.HE↗

arXiv2023

Comprehensive Measurement Forecasts of the EeV Neutrino-Nucleon Cross Section with Cosmic Neutrinos at IceCube-Gen2

The investigation of neutrino interactions with matter serves as a valuable tool for understanding the fundamental structure of nucleons and potentially uncovering novel physics phenomena. To date, the neutrino-nucleon cross section has been examined across a range of energies spanning from a few hundred MeV to PeV. However, the pursuit of ultra-high-energy (UHE) cosmic neutrinos, surpassing 100 PeV in energy, holds the promise of further advancements. In the next 10-20 years, UHE neutrino telescopes, currently in the planning stage, may ultimately succeed in their detection. This article presents pioneering and comprehensive estimation forecasts for the ultra-high-energy neutrino-nucleon cross section, with a specific focus on the employment of neutrino radio-detection within the IceCube-Gen2 experiment. The study incorporates cutting-edge methodologies in UHE neutrino flux prediction, neutrino propagation within the Earth, radio detection techniques, and the treatment of background data to facilitate accurate cross section measurement projections. Assuming the successful detection of at least a few tens of UHE neutrino-induced events over a 10-year period, IceCube-Gen2 could achieve, for the first time, the measurement of the cross section at center-of-mass energies of approximately $\sqrt{s} \approx 10$--100 TeV. Furthermore, if the number of events exceeds one hundred, the precision of the cross section measurement could be comparable to its corresponding theoretical prediction.

hep-ph↗

arXiv2023

Discovery Forecasts of the Diffuse Ultra-High-Energy Neutrino Flux with IceCube-Gen2

The discovery of ultra-high-energy (UHE) neutrinos has the potential to offer unique insight into fundamental questions. To capitalize on the upcoming opportunity provided by new UHE neutrino telescopes, we provide state-of-the-art forecasts of the discovery of a diffuse flux of UHE neutrinos over the next 10-20 years, focusing on neutrino radio-detection in the planned IceCube-Gen2 detector. We use state-of-the-art flux predictions and detector modeling. We find that, even under conservative analysis choices, most benchmark UHE neutrino flux models from the literature may be discovered within 10 years of detector exposure, with many discoverable sooner, and may be distinguished from each other. Our results demonstrate the transformative potential of next-generation UHE neutrino telescopes.

astro-ph.HE↗

arXiv2023

Results from the ARIANNA high-energy neutrino detector

The ARIANNA in-ice radio detector explores the detection of UHE neutrinos with shallow detector stations on the Ross Ice Shelf and the South Pole. Here, we present recent results that lay the foundation for future large-scale experiments. We show a limit on the UHE neutrino flux derived from ARIANNA data, measurements of the more abundant air showers, results from in-situ measurement campaigns, a study of a potential background from internal reflection layers, and give an outlook of future detector improvements.

astro-ph.IM↗

arXiv2023

Near-future discovery of the diffuse flux of ultra-high-energy cosmic neutrinos

Ultra-high-energy (UHE) neutrinos, with EeV-scale energies, carry with them unique insight into fundamental open questions in astrophysics and particle physics. For fifty years, they have evaded discovery, but maybe not for much longer, thanks to new UHE neutrino telescopes, presently under development. We capitalize on this upcoming opportunity by producing state-of-the-art forecasts of the discovery of a diffuse flux of UHE neutrinos in the next 10-20 years. By design, our forecasts are anchored in often-overlooked nuance from theory and experiment; we gear them to the radio array of the planned IceCube-Gen2 detector. We find encouraging prospects: even under conservative analysis choices, most benchmark UHE neutrino flux models available in the literature may be discovered within 10 years of detector exposure -- many sooner -- and may be distinguished from each other. Our results validate the transformative potential of next-generation UHE neutrino telescopes.

astro-ph.HE↗

arXiv2023

Simulation study for an in-situ calibration system for the measurement of the snow accumulation and the index-of-refraction profile for radio neutrino detectors

Sensitivity to ultra-high-energy neutrinos ($E>10^{17}$eV) can be obtained cost-efficiently by exploiting the Askaryan effect in ice, where a particle cascade induced by the neutrino interaction produces coherent radio emission that can be picked up by antennas. As the near-surface ice properties change rapidly within the upper $\mathcal{O}$(100m), a good understanding of the ice properties is required to reconstruct the neutrino properties. In particular, continuous monitoring of the snow accumulation (which changes the depth of the antennas) and the index-of-refraction $n(z)$ profile are crucial for an accurate determination of the neutrino's direction and energy. We present an in-situ calibration system that extends the radio detector station with two radio emitters to continuously monitor the firn properties within the upper 40m by measuring the time differences between direct and reflected (off the surface) signals (D'n'R). We determine the optimal positions of two transmitters at all three sites of current and future in-ice radio detectors: Greenland, Moore's Bay, and the South Pole. For the South Pole we find that the snow accumulation $Δh$ can be measured with a resolution of 3mm and the parameters of an exponential $n(z)$ profile $α$ and $z_0$ with 0.04% and 0.14% precision respectively, which constitutes an improvement of more than a factor of 10 as compared to the inference of the $n(z)$ profile from density measurements. Additionally, as this technique is based on the measurement of the signal propagation times we are not bound to the conversion of density to index-of-refraction. We quantify the impact of these ice uncertainties on the reconstruction of the neutrino vertex, direction, and energy and find that the calibration device measures the ice properties to sufficient precision to have negligible influence.

astro-ph.IM↗

arXiv2023

Radio Detection of High Energy Neutrinos in Ice

Radio-based detection of high-energy particles is growing in maturity. In this chapter, we focus on the detection of neutrinos with energies in excess of 10 PeV that interact in the thick, radio-transparent ice found in the polar regions. High-energy neutrinos interacting in the ice generate short duration, radio-frequency flashes through the Askaryan effect that can be measured with antennas installed at shallow depths. The abundant target material and the long attenuation lengths of around 1 km allow cost-effective instrumentation of huge volumes with a sparse array of radio detector stations. This detector architecture provides sufficient sensitivity to the low flux of ultra-high-energy neutrinos to probe the production of ultra-high-energy cosmic rays whose origin is one of the longest-standing riddles in astroparticle physics. We describe the signal characteristics, propagation effects, detector setup, suitable detection sites, and background processes. We give an overview of the current experimental landscape and an outlook into the future where almost the entire sky can be viewed by a judicious choice of detector locations.

astro-ph.IM↗