arXiv subjects

Julian Rautenberg

Publications and source records attributed to Julian Rautenberg.

13 recordsLinked to original sources

arXiv2026

Downward ultra-high-energy neutrino detection in the air with radio antennas at ground-based observatories

Ultra-high-energy (UHE) neutrinos are unique cosmic messengers that can traverse cosmological distances unattenuated, providing direct insight into the most energetic processes in the universe. Radio detection offers significant advantages for detecting highly inclined air showers induced by UHE neutrinos. This is due to a larger exposure range compared to particle detectors, which is a result of minimal atmospheric attenuation of radio signals combined with good reconstruction precision. Furthermore, this technique improves the air shower longitudinal reconstruction, which can be used to identify neutrinos with their first interaction far below the top of the atmosphere. In this work, we present a method for identifying UHE neutrinos using ground-based radio antennas. A reconstruction algorithm is introduced based on the radio emission maximum ($X^{\text{radio}}_{\text{max}}$), which demonstrates its power in distinguishing deeply developing neutrino-induced showers from background cosmic rays. Using simulations of $\nu_e$-CC-induced air showers, we evaluate the trigger efficiency, reconstruction performance, and resulting effective area and aperture prediction for a reference array. Our results show that radio detection significantly enhances the sensitivity to very inclined showers above 1 EeV, complementing traditional surface detectors. This technique is highly scalable and applicable to future radio observatories, such as GRAND. The proposed reconstruction and identification strategy provides a pathway toward achieving the sensitivity required to detect UHE neutrinos.

astro-ph.HE↗

arXiv2025

Ultra-high-energy neutrino detection with radio antennas in the ground-based observatory

Ultra-high-energy (UHE) neutrinos are unique cosmic messengers that can traverse cosmological distances unattenuated, offering direct insight into the most energetic processes in the universe. Radio detection promises significant advantages for detecting highly inclined air showers induced by UHE neutrinos, including a larger exposure range compared to particle detectors, which is due to minimal atmospheric attenuation of radio signals combined with good reconstruction precision. Furthermore, this technique improves the air shower longitudinal reconstruction, which can be used to identify neutrinos with their first interaction far below the top of the atmosphere. In this work, we present a method for identifying UHE neutrinos using radio antennas deployed in ground-based observatories. We introduce a reconstruction algorithm based on the radio emission maximum ($X^{\text{radio}}_{\text{max}}$) and demonstrate its power in distinguishing deeply developing neutrino-induced showers from background cosmic rays. Using the Pierre Auger Observatory as a case study, we use the simulations of $\nu_e$-CC-induced air showers and evaluate the trigger efficiency, reconstruction performance, and resulting effective area. Our results show that radio detection significantly enhances the sensitivity to very inclined showers above 1~EeV, complementing traditional surface detectors. This technique is highly scalable and applicable to future radio observatories such as GRAND. The proposed reconstruction and identification strategy provides a pathway toward achieving the sensitivity needed to detect UHE neutrinos.

astro-ph.HE↗

arXiv2025

Road map for the tuning of hadronic interaction models with accelerator-based and astroparticle data

In high-energy and astroparticle physics, event generators play an essential role, even in the simplest data analyses. As analysis techniques become more sophisticated, e.g. based on deep neural networks, their correct description of the observed event characteristics becomes even more important. Physical processes occurring in hadronic collisions are simulated within a Monte Carlo framework. A major challenge is the modeling of hadron dynamics at low momentum transfer, which includes the initial and final phases of every hadronic collision. QCD-inspired phenomenological models used for these phases cannot guarantee completeness or correctness over the full phase space. These models usually include parameters which must be tuned to suitable experimental data. Until now, event generators have been developed and tuned mainly on the basis of data from high-energy physics experiments at accelerators. The wealth of data available from the latest generation of astroparticle experiments has not yet been fully exploited, and in many cases is not satisfactorily described. Both kinds of data sets are complementary as astroparticle experiments provide sensitivity especially to hadrons produced nearly parallel to the collision axis and cover center-of-mass energies up to several hundred TeV, well beyond those reached at colliders so far. In this report, we provide an overview of state-of-the-art event generators and their tuning, including the most relevant inputs from high-energy accelerator and astroparticle experiments. We present a road map that shows, for the first time, how the unified tuning of event generators with accelerator-based and astroparticle data can be performed.

astro-ph.HE↗

arXiv2025

Stochastic description of UHECR interactions

Photointeractions of ultra-high energy cosmic rays (UHECRs) in astro-physical scenarios are in general of stochastic nature and are often modeled with Monte Carlo methods to obtain the form of the distributions resulting from a sequence of interactions. These distributions are non trivial because the products resulting from each interaction as well as the number and distances covered by the secondary nuclear species are all random. In this work, a stochastic approach based on the theory of matrix exponential distributions is employed to describe the cascade distributions analytically and illustrate their potential for tracing the individual history of UHECRs, including inside the source. This analytic description has the advantage of better precision and considerably reduced computational cost in contrast to Monte Carlo codes, while requiring the same inputs: the interaction rates, the multiplicity, and the energy distributions of secondaries from a single interaction. The description of the composition evolution from in-source to extragalactic propagation (currently performed in separate simulations in the literature) is achieved here as a continuous distribution, using a gamma-ray burst scenario inspired by the event GRB170817A. Finally, the potential for locating a source based on the reconstructed UHECR origin employing this description is discussed under simplified general assumptions.

astro-ph.HE↗

arXiv2024

Photon-likeness of hadron showers and impact of Lorentz boosting

We examine the probability of proton-induced air showers at $E>10\,$EeV being misidentified as photon-induced due to neutral pions receiving a major part of the primary energy in the first interaction, thereby enhancing the electromagnetic shower component by their $\pi^0 \to \gamma \gamma$ decay. Using CORSIKA simulations, we demonstrate the relevance of this effect at EeV energies. However, the probability for such photon-like events drops down strongly at the highest energies due to the increasing probability of Lorentz boosted $\pi^0$'s suffering hadronic interactions before decay. Different hadronic interaction models suggest that photon-like hadronic events may be observed at current UHECR observatories. A quantitative comparison of the observed number of background events found in recent photon searches published by the Pierre Auger Collaboration allows us conclude that the hypothesis of upwards fluctuations of $\pi^0$-production alone is insufficient to explain the data.

hep-ph↗

arXiv2021

Hunting super-heavy dark matter with ultra-high energy photons

At any epoch, particle physics must be open to completely unexpected discoveries, and that is reason enough to extend the reach of searches for ultra-high energy (UHE) photons. The observation of a population of photons with energies $E \gtrsim 100$ EeV would for example imply the existence of either a completely new physical phenomena, or particle acceleration mechanisms heretofore never seen or imagined. But as we outline in this Letter of Interest, there are also good arguments for super-heavy dark matter (SHDM) in a parameter range such that it could be discovered via its decays to, in particular, UHE photons. Only ultra-high energy cosmic ray observatories have capabilities to detect UHE photons. We first investigate how current and future observations can probe and constrain SHDM models in important directions, and then outline some of the scenarios that motivate such searches. We also discuss connections between constraints on SHDM and on the parameter values of cosmological models.

hep-ph↗

arXiv2020

Refractive displacement of the radio-emission footprint of inclined air showers simulated with CoREAS

The footprint of radio emission from extensive air showers is known to exhibit asymmetries due to the superposition of geomagnetic and charge-excess radiation. For inclined air showers a geometric early-late effect disturbs the signal distribution further. Correcting CoREAS simulations for these asymmetries reveals an additional disturbance in the signal distribution of highly inclined showers in atmospheres with a realistic refractive index profile. This additional apparent asymmetry in fact arises from a systematic displacement of the radio-emission footprint with respect to the Monte-Carlo shower impact point on the ground. We find a displacement of $\sim 1500\,\text{m}$ in the ground plane for showers with a zenith angle of $85^\circ$, illustrating that the effect is relevant in practical applications. A model describing this displacement by refraction in the atmosphere based on Snell's law yields good agreement with our observations from CoREAS simulations. We thus conclude that the displacement is caused by refraction in the atmosphere.

astro-ph.IM↗

arXiv2018

Determination of the absolute energy scale of extensive air showers via radio emission: systematic uncertainty of underlying first-principle calculations

Recently, the energy determination of extensive air showers using radio emission has been shown to be both precise and accurate. In particular, radio detection offers the opportunity for an independent measurement of the absolute energy scale of cosmic rays, since the radiation energy (the energy radiated in the form of radio signals) can be predicted using first-principle calculations involving no free parameters, and the measurement of radio waves is not subject to any significant absorption or scattering in the atmosphere. To quantify the uncertainty associated with such an approach, we collate the various contributions to the uncertainty, and we verify the consistency of radiation-energy calculations from microscopic simulation codes by comparing Monte Carlo simulations made with the two codes CoREAS and ZHAireS. We compare a large set of simulations with different primary energies and shower directions and observe differences in the radiation energy prediction for the 30 - 80 MHz band of 5.2 %. This corresponds to an uncertainty of 2.6 % for the determination of the absolute cosmic-ray energy scale. Our result has general validity and can be built upon directly by experimental efforts for the calibration of the cosmic-ray energy scale on the basis of radio emission measurements.

astro-ph.HE↗

arXiv2017

Modelling uncertainty of the radiation energy emitted by extensive air showers

Recently, the energy determination of extensive air showers using radio emission has been shown to be both precise and accurate. In particular, radio detection offers the opportunity for an independent measurement of the absolute energy of cosmic rays, since the radiation energy (the energy radiated in the form of radio signals) can be predicted using first-principle calculations involving no free parameters, and the measurement of radio waves is not subject to any significant absorption or scattering in the atmosphere. Here, we verify the implementation of radiation-energy calculations from microscopic simulation codes by comparing Monte Carlo simulations made with the two codes CoREAS and ZHAireS. To isolate potential differences in the radio-emission calculation from differences in the air-shower simulation, the simulations are performed with equivalent settings, especially the same model for the hadronic interactions and the description of the atmosphere. Comparing a large set of simulations with different primary energies and shower directions we observe differences amounting to a total of only 3.3 %. This corresponds to an uncertainty of only 1.6 % in the determination of the absolute energy scale and thus opens the potential of using the radiation energy as an accurate calibration method for cosmic ray experiments.

astro-ph.HE↗

arXiv2015

High energy astroparticle physics for high school students

The questions about the origin and type of cosmic particles are not only fascinating for scientists in astrophysics, but also for young enthusiastic high school students. To familiarize them with research in astroparticle physics, the Pierre Auger Collaboration agreed to make 1% of its data publicly available. The Pierre Auger Observatory investigates cosmic rays at the highest energies and consists of more than 1600 water Cherenkov detectors, located near Malargüe, Argentina. With publicly available data from the experiment, students can perform their own hands-on analysis. In the framework of a so-called Astroparticle Masterclass organized alongside the context of the German outreach network Netzwerk Teilchenwelt, students get a valuable insight into cosmic ray physics and scientific research concepts. We present the project and experiences with students.

astro-ph.IM↗

arXiv2015

Prospects of GPGPU in the Auger Offline Software Framework

The Pierre Auger Observatory is the currently largest experiment dedicated to unveil the nature and origin of the highest energetic cosmic rays. The software framework 'Offline' has been developed by the Pierre Auger Collaboration for joint analysis of data from different independent detector systems used in one observatory. While reconstruction modules are specific to the Pierre Auger Observatory components of the Offline framework are also used by other experiments. The software framework has recently been extended to incorporate data from the Auger Engineering Radio Array (AERA), the radio extension of the Pierre Auger Observatory. The reconstruction of the data of such radio detectors requires the repeated evaluation of complex antenna gain patterns which significantly increases the required computing resources in the joint analysis. In this contribution we explore the usability of massive parallelization of parts of the Offline code on the GPU. We present the result of a systematic profiling of the joint analysis of the Offline software framework aiming for the identification of code areas suitable for parallelization on GPUs. Possible strategies and obstacles for the usage of GPGPU in an existing experiment framework are discussed.

astro-ph.IM↗

arXiv2005

Measurement of high-Q2 deep inelastic scattering cross sections with longitudinally polarised positron beams at HERA

The first measurements of the cross sections for neutral and charged current deep inelastic scattering in e+p collisions with longitudinally polarised positron beams are presented. The total cross section for e+p charged current deep inelastic scattering is presented at positive and negative values of positron beam longitudinal polarisation for an integrated luminosity of 37.0 pb^-1 H1 data and 30.5 pb^-1 ZEUS data collected in 2003 and 2004 at a centre-of-mass energy of 319 GeV. In addition, the ZEUS collaboration measured the single differential cross sections for charged and neutral current deep inelastic scattering in the kinematic region Q^2>200 GeV^2. The measured cross sections are compared with the predictions of the Standard Model. The H1 collaboration extrapolate the cross section to a fully left handed positron beam and find it to be consistent with the Standard Model expectation.

hep-ex↗

arXiv2003

ZEUS results on high Q^2 DIS cross sections and QCD fits

Single and double differential cross sections ds/dQ^2, ds/dx, ds/dy and d^2s/dQ^2dx of the inclusive neutral current (NC) measurement from the 98/99 e^-p and the charged current (CC) measurement from the 99/00 e^+p data sets are presented. With the previously published e^+p NC ZEUS measurement xF_3 and xG_3, and with the e^-p CC ZEUS measurement F_2^CC are extracted. The results are compared to the prediction of the Standard Model using parton density functions of the ZEUS next-to-leading-order QCD analysis which is reviewed.

hep-ex↗