arXiv subjects

Alexander Sandrock

Publications and source records attributed to Alexander Sandrock.

15 recordsLinked to original sources

arXiv2025

Cosmic-Ray Boosted Diffuse Supernova Neutrinos

The subject of boosted fluxes of dark matter or cosmic relic neutrinos via scattering on cosmic rays has received considerable attention recently. This article investigates the boosted neutrino flux from scattering of cosmic rays and the so-far undetected diffuse supernova neutrino background, taking into account both galactic and extragalactic cosmic rays. The calculated flux is many orders of magnitude smaller than either the galactic diffuse neutrino emission, the extragalactic astrophysical flux measured by IceCube, or the cosmogenic neutrino flux expected at the highest energies.

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

Impact of coherent scattering on relic neutrinos boosted by cosmic rays

Ultra-high-energy cosmic rays (UHECR) scattering off the cosmic relic neutrino background have recently gained renewed interest in the literature. Current data suggest that (UHECR) are predominantly made of heavy nuclei. Similar to the coherent elastic neutrino-nucleus scattering (CE$\nu$NS) observed at low-energy neutrino experiments, the cross section of heavy nucleus scattering off relic neutrinos will be coherently enhanced since the energy of relic neutrinos can reach $\sim O(10)$ MeV in the rest frame of the UHECR. We calculate the diffuse flux of relic neutrinos boosted by UHECR after taking into account the contributions from both coherent and incoherent scatterings. Using current data from IceCube and Pierre Auger Observatory, we place constraints on the overdensity of relic neutrinos down to $\sim 10^8$. Since the flux of boosted relic neutrinos peaks at an energy of $\sim 200\, \text{PeV}$, we also entertain the possibility to explain the recently observed KM3NeT event with boosted relic neutrinos from UHECR.

hep-ph↗

arXiv2023

Improvements in charged lepton and photon propagation for the software PROPOSAL

Accurate particle simulations are essential for the next generation of experiments in astroparticle physics. The Monte Carlo simulation library PROPOSAL is a flexible tool to efficiently propagate high-energy leptons and photons through large volumes of media, for example in the context of underground observatories. It is written as a C++ library, including a Python interface. In this paper, the most recent updates of PROPOSAL are described, including the addition of electron, positron, and photon propagation, for which new interaction types have been implemented. This allows the usage of PROPOSAL to simulate electromagnetic particle cascades, for example in the context of air shower simulations. The precision of the propagation has been improved by including rare interaction processes, new photonuclear parametrizations, deflections in stochastic interactions, and the possibility of propagating in inhomogeneous density distributions. Additional technical improvements regarding the interpolation routine and the propagation algorithm are described.

astro-ph.IM↗

arXiv2023

Modified temperature redshift relation and UHECR propagation

We re-examine the interactions of ultra-high energy cosmic rays (UHECRs) with photons from the cosmic microwave background (CMB) under a changed, locally non-linear temperature redshift relation $T(z)$. This changed temperature redshift relation has recently been suggested by the postulate of subjecting thermalised and isotropic photon gases such as the CMB to an SU(2) rather than a U(1) gauge group. This modification of $\Lambda$CDM is called SU(2)$_{\rm CMB}$, and some cosmological parameters obtained by SU(2)$_{\rm CMB}$ seem to be in better agreement with local measurements of the same quantities, in particular $H_0$ and S$_8$. In this work, we apply the reduced CMB photon density under SU(2)$_{\rm CMB}$ to the propagation of UHECRs. This leads to a higher UHECR flux just below the ankle in the cosmic ray spectrum and slightly more cosmogenic neutrinos under otherwise equal conditions for emission and propagation. Most prominently, the proton flux is significantly increased below the ankle ($5\times10^{18}$ eV) for hard injection spectra and without considering the effects of magnetic fields. The reduction in CMB photon density also favours a decreased cosmic ray source evolution than the best fit using $\Lambda$CDM. In consequence, it seems that SU(2)$_{\rm CMB}$ favours sources that evolve as the star formation rate (SFR), like starburst galaxies (SBG) and gamma-ray bursts (GRB), over active galactic nuclei (AGNs) as origins of UHECRs. We conclude that the question about the nature of primary sources of UHECRs is directly affected by the assumed temperature redshift relation of the CMB.

astro-ph.HE↗

arXiv2023

The Relevance of Muon Deflections for Neutrino Telescopes

Large-scale neutrino telescopes have the primary objective to detect and characterize neutrino sources in the universe. These experiments rely on the detection of charged leptons produced in the interaction of neutrinos with nuclei. Angular resolutions are estimated to be better than 1 degree, which is achieved by the reconstruction of muons. This angular resolution is a measure of the accuracy with which the direction of incoming neutrinos can be determined. Since muons can traverse distances of several kilometers through media, the original muon direction can differ from the muon direction inside the detector due to deflections by stochastic interactions and multiple scattering. In this contribution, a recently published study of muon deflections based on the simulation tool PROPOSAL is presented. Muons with various energies are propagated through different media over several distances. Data-Monte-Carlo comparisons as well as comparisons to the simulation tools MUSIC and Geant4 are performed. Finally, the impact of muon deflections on large-scale neutrino telescopes is discussed.

hep-ex↗

arXiv2023

Validation of Electromagnetic Showers in CORSIKA 8

The air shower simulation code CORSIKA has served as a key part of the simulation chain for numerous astroparticle physics experiments over the past decades. Due to retirement of the original developers and the increasingly difficult maintenance of the monolithic Fortran code of CORSIKA, a new air shower simulation framework has been developed over the course of the last years in C++, called CORSIKA 8. Besides the hadronic and muonic component, the electromagnetic component is one of the key constituents of an air shower. The cascade producing the electromagnetic component of an air shower is driven by bremsstrahlung and photoproduction of electron-positron pairs. At ultrahigh energies or in media with high densities, the bremsstrahlung and pair production processes are suppressed by the Landau-Pomeranchuk-Migdal (LPM) effect, which leads to more elongated showers compared to showers without the LPM suppression. Furthermore, photons at higher energies can produce muon pairs or interact hadronically with nucleons in the target medium, producing a muon component in electromagnetic air showers. In this contribution, we compare electromagnetic showers simulated with the latest Fortran version of CORSIKA and CORSIKA 8, which uses the library PROPOSAL for the electromagnetic component. While earlier validations of CORSIKA 8 electromagnetic showers focused on showers of lower energy, the recent implementation of the LPM effect, photo pair production of muons, and of photohadronic interactions allows now to make a physics-complete comparison also at high energies.

astro-ph.HE↗

arXiv2023

Simulation of Deflection Uncertainties on Directional Reconstructions of Muons Using PROPOSAL

Large scale neutrino detectors and muon tomography rely on the muon direction in the detector to infer the muon's or parent neutrino's origin. However, muons accumulate deflections along their propagation path prior to entering the detector, which may need to be accounted for as an additional source of uncertainty. In this paper, the deflection of muons is studied with the simulation tool PROPOSAL, which accounts for multiple scattering and deflection on stochastic interactions. Deflections along individual interactions depend on the muon energy and the interaction type, and can reach up to the order of degrees -- even at TeV to PeV energies. The accumulated deflection angle can be parametrized in dependence of the final muon energy, independent of the initial muon energy. The median accumulated deflection of a propagated muon with a final energy of 500 GeV is $θ_{\text{acc}} = 0.10°$ with a 99 % central interval of $[0.01°, 0.39°]$. This is on the order of magnitude of the directional resolution of present neutrino detectors. Furthermore, comparisons with the simulation tools MUSIC and Geant4 as well as two different muon deflection measurements are performed.

astro-ph.IM↗

arXiv2022

Status and prospects of the CORSIKA 8 air shower simulation framework

The Fortran-versions of the CORSIKA air shower simulation code have been at the core of simulations for many astroparticle physics experiments for the last 30 years. Having grown over decades into an ever more complex software, maintainability of CORSIKA has become increasingly difficult, though its performance is still excellent. In 2018, therefore a complete rewrite of CORSIKA has begun in modern modular C++. Today, CORSIKA 8 has reached important milestones with a full-fledged implementation of both the hadronic and electromagnetic cascades, the ability to simulate radio and Cherenkov-light emission from air showers and an unprecedented flexibility to configure simulation media and their geometries. This presentation will discuss the current status of CORSIKA 8, highlight the new possibilities already available, and future prospects of this new air shower simulation framework.

astro-ph.HE↗

arXiv2021

CORSIKA 8 -- Contributions to the 37th International Cosmic Ray Conference in Berlin Germany (ICRC 2021)

Compilation of the six contributions to the ICRC conference 2021 by the CORSIKA 8 Collaboration. The status of the project is illustrated. In particular, the secondary hadron as well as the electromagnetic cascades are being validated individually, and current results are reviewed. A novel framework for radio emission simulations is presented, which is designed given the modular nature of CORSIKA 8 to support, both, the CoREAS as well as the ZHS formalism. At the same time, first Cherenkov emission calculations are shown which are based on CORSIKA 8 coupled with a GPU Cherenkov emission code. Finally, a new powerful feature of CORSIKA 8 is illustrated, where the entire genealogy of air shower particles can be studied in all details.

astro-ph.HE↗

arXiv2020

Estimation of an Upper Limit on the Density of Relic Neutrinos in the Sun via the Solar $^8$B Neutrino Flux

Relic neutrinos from the early universe are predicted to have a relatively large number density, but extremely low energies. Hence, the only possible interaction proceeds via neutrino capture on beta-decaying nuclei. In case relic neutrinos are captured by beta-decaying nuclei in the Sun, the neutrinos normally emerging from the decay of these nuclei will be missing from the overall number of solar neutrinos registered in neutrino experiments. Within the Sun, ${}^8\mathrm{B}$ and three nuclei from the CNO cycle are found to be suitable for this kind of process. Their cross section as well as the possible impact on the observed number of solar neutrinos are discussed. Assuming standard neutrino oscillations, no deviations of neutrino flux measurements from the predictions of the solar standard model are observed and upper limits are derived accordingly.

hep-ph↗

arXiv2019

The effect of improved high-energy muon cross-sections

A precise simulation of muons with energies above a TeV is crucial for neutrino telescopes or cosmic ray experiments. To further increase the precision of these simulations, improved cross-section calculations are needed. At these energies, the interaction probability is dominated by bremsstrahlung for large energy losses and electron-positron pair production for small energy losses. Improved analytical calculations for these processes were developed with more precise screening functions of the target atom as well as higher order corrections reducing the systematic uncertainties below the percent level. The new calculations are already implemented in the new version of the lepton propagator PROPOSAL, which was designed to be highly performant for the propagation through large volumes of media using interpolation tables and to do systematic studies with its multiple available cross-section calculations. The new calculations of the differential cross-section result in a maximum deviation of 3 percent to the current standard. Their effects on the muon simulation with the resulting flux and energy loss distribution are presented.

hep-ph↗

arXiv2018

Recent Improvements for the Lepton Propagator PROPOSAL

The lepton propagator PROPOSAL is a Monte-Carlo Simulation library written in C++, propagating high energy muons and other charged particles through large distances of media. In this article, a restructuring of the code is described, which yields a performance improvement of up to $30\,\%$. For an improved accuracy of the propagation processes, more exact calculations of the leptonic and hadronic decay process and more precise parametrizations for the interaction cross sections are now available. The new modular structure allows a more flexible and custom usage, which is further facilitated with a python interface.

hep-ph↗

arXiv2018

Coulomb corrections to the bremsstrahlung and electron pair production cross section of high-energy muons on extended nuclei

The energy reconstruction of high-energy muons depends on the energy loss characteristics. Accurate knowledge of the cross sections of the energy loss processes is necessary for precise measurements of the energy spectrum of muons and muon-induced neutrinos. The cross sections of the two most dominant processes, electron pair production and bremsstrahlung are calculated exact in the coupling parameter $Zα$ to the electromagnetic field of a nucleus for realistic extended screened nuclei. An analytical parametrization of the mass and nuclear-charge dependence of the cross section is given.

hep-ph↗

arXiv2017

Radiative corrections to the average bremsstrahlung energy loss of high-energy muons

High-energy muons can travel large thicknesses of matter. For underground neutrino and cosmic ray detectors the energy loss of muons has to be known accurately for simulations. In this article the next-to-leading order correction to the average energy loss of muons through bremsstrahlung is calculated using a modified Weizsäcker-Williams method. An analytical parametrisation of the numerical results is given.

hep-ph↗