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Dennis Soldin

Publications and source records attributed to Dennis Soldin.

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The Forward Physics Facility at the High-Luminosity LHC

High energy collisions at the High-Luminosity Large Hadron Collider (LHC) produce a large number of particles along the beam collision axis, outside of the acceptance of existing LHC experiments. The proposed Forward Physics Facility (FPF), to be located several hundred meters from the ATLAS interaction point and shielded by concrete and rock, will host a suite of experiments to probe Standard Model (SM) processes and search for physics beyond the Standard Model (BSM). In this report, we review the status of the civil engineering plans and the experiments to explore the diverse physics signals that can be uniquely probed in the forward region. FPF experiments will be sensitive to a broad range of BSM physics through searches for new particle scattering or decay signatures and deviations from SM expectations in high statistics analyses with TeV neutrinos in this low-background environment. High statistics neutrino detection will also provide valuable data for fundamental topics in perturbative and non-perturbative QCD and in weak interactions. Experiments at the FPF will enable synergies between forward particle production at the LHC and astroparticle physics to be exploited. We report here on these physics topics, on infrastructure, detector, and simulation studies, and on future directions to realize the FPF's physics potential.

hep-ex↗

Update on the Combined Analysis of Muon Measurements from Nine Air Shower Experiments

Over the last two decades, various experiments have measured muon densities in extensive air showers over several orders of magnitude in primary energy. While some experiments observed differences in the muon densities between simulated and experimentally measured air showers, others reported no discrepancies. We will present an update of the meta-analysis of muon measurements from nine air shower experiments, covering shower energies between a few PeV and tens of EeV and muon threshold energies from a few 100 MeV to about 10 GeV. In order to compare measurements from different experiments, their energy scale was cross-calibrated and the experimental data has been compared using a universal reference scale based on air shower simulations. Above 10 PeV, we find a muon excess with respect to simulations for all hadronic interaction models, which is increasing with shower energy. For EPOS-LHC and QGSJet-II.04 the significance of the slope of the increase is analyzed in detail under different assumptions of the individual experimental uncertainties.

astro-ph.HE↗

On the muon scale of air showers and its application to the AGASA data

Recently, several experiments reported a muon deficit in air shower simulations with respect to the data. This problem can be studied using an estimator that quantifies the relative muon content of the data with respect to those of proton and iron Monte Carlo air shower simulations. We analyze two estimators. The first one, based on the logarithm of the mean of the muon content, is built from experimental considerations. It is ideal for comparing results from different experiments as it is independent of the detector resolution. The second estimator is based on the mean of the logarithm of the muon content, which implies that it depends on shower-to-shower fluctuations. It is linked to the mean-logarithmic mass $\left \langle \ln A \right \rangle$ through the Heitler-Matthews model. We study the properties of the estimators and their biases considering the knowns and unknowns of typical experiments. Furthermore, we study these effects in measurements of the muon density at $1000\,$m from the shower axis obtained by the Akeno Giant Air Shower Array (AGASA). Finally, we report the estimates of the relative muon content of the AGASA data, which support a muon deficit in simulations. These estimates constitute valuable additional information of the muon content of air showers at the highest energies.

astro-ph.HE↗

Testing Hadronic Interaction Models with Cosmic Ray Measurements at the IceCube Neutrino Observatory

The IceCube Neutrino Observatory provides the opportunity to perform unique measurements of cosmic-ray air showers with its combination of a surface array and a deep detector. Electromagnetic particles and low-energy muons ($\sim$GeV) are detected by IceTop, while a bundle of high-energy muons ($\gtrsim$400 GeV) can be measured in coincidence in IceCube. Predictions of air-shower observables based on simulations show a strong dependence on the choice of the high-energy hadronic interaction model. By reconstructing different composition-dependent observables, one can provide strong tests of hadronic interaction models, as these measurements should be consistent with one another. In this work, we present an analysis of air-shower data between 2.5 and 80 PeV, comparing the composition interpretation of measurements of the surface muon density, the slope of the IceTop lateral distribution function, and the energy loss of the muon bundle, using the models Sibyll 2.1, QGSJet-II.04 and EPOS-LHC. We observe inconsistencies in all models under consideration, suggesting they do not give an adequate description of experimental data. The results furthermore imply a significant uncertainty in the determination of the cosmic-ray mass composition through indirect measurements.

astro-ph.HE↗

Density of GeV Muons Measured with IceTop

We present a measurement of the density of GeV muons in near-vertical air showers using three years of data recorded by the IceTop array at the South Pole. We derive the muon densities as functions of energy at reference distances of 600 m and 800 m for primary energies between 2.5 PeV and 40 PeV and between 9 PeV and 120 PeV, respectively, at an atmospheric depth of about $690\,\mathrm{g/cm}^2$. The measurements are consistent with the predicted muon densities obtained from Sibyll~2.1 assuming any physically reasonable cosmic ray flux model. However, comparison to the post-LHC models QGSJet-II.04 and EPOS-LHC shows that the post-LHC models yield a higher muon density than predicted by Sibyll 2.1 and are in tension with the experimental data for air shower energies between 2.5 PeV and 120 PeV.

astro-ph.HE↗

Precision of analytical approximations in calculations of Atmospheric Leptons

We use the Matrix Cascade Equation code (MCEq) to evaluate the range of applicability of simple analytic approximations parameterized by spectrum-weighted moments and power-law spectral indices that vary slowly with energy. We compare spectra of leptons as a function of zenith angle and energy between MCEq and the analytic approximation. We also compare fluxes obtained with different models of hadronic interactions. The goal is to quantify the effects of the approximations inherent in the simpler formulas in order to determine their limitations and the conditions under which they may be used. Specifically we look for the range of phase space for which the errors in the approximate formulas are smaller than the differences among several different hadronic interaction models. Potential applications include the muon charge ratio, the fraction of prompt leptons from decay of charm and seasonal variations of muons and neutrinos.

astro-ph.HE↗

Recent Results of Cosmic Ray Measurements from IceCube and IceTop

IceCube is a cubic-kilometer Cherenkov detector located in the deep ice at the geographic South Pole. The dominant event yield in the deep ice detector consists of penetrating atmospheric muons produced in cosmic ray air showers with energies above several 100 GeV. In addition, the surface array, IceTop, deployed above the IceCube deep ice detector, measures the electromagnetic signal and low-energy muons of the air shower. Hence, IceCube and IceTop yield unique opportunities to study cosmic rays with large statistics in great detail. We discuss the latest results of air shower measurements from IceCube and IceTop, including the energy spectrum of cosmic rays from 250 TeV up to the EeV range. We will also report a measurement of the cosmic ray mass composition in the PeV to EeV range and show recent results from searches for PeV gamma ray sources in the Southern Hemisphere. In addition, results from a full-sky analysis of the cosmic ray anisotropy, using combined data from the IceCube and HAWC observatories, will be reported. Finally, we will present a measurement of the density of muons in the GeV range and discuss its consistency with predictions from hadronic interaction models.

astro-ph.HE↗

Seasonal variation of atmospheric muons in IceCube

After more than seven years of data taking with the full IceCube detector triggering at an average rate of 2.15 kHz, a sample of half a trillion muon events is available for analysis. The extreme temperature variations in the stratosphere together with the high data rate reveal features on both long and short time scales with unprecedented precision. In this paper we report an analysis in terms of the atmospheric profile for production of muons from decay of charged pions and kaons. We comment on the implications for seasonal variations of neutrinos, which are presented in a separate paper at this conference.

astro-ph.HE↗

A Three-dimensional Reconstruction of Cosmic Ray Events in IceCube

The IceCube Neutrino Observatory at the geographic South Pole consists of two components, a km2 surface array IceTop and a km3 in-ice array between 1.5 and 2.5 km below the surface. Cosmic ray events with primary energy above a few tens of TeV may trigger both the IceTop and in-ice array and leave a three-dimensional footprint of the electromagnetic and muonic components in the extensive air shower. A new reconstruction based on the minimization of a unified likelihood function involving quantities measured by both IceTop and in-ice detectors was developed. This report describes the new reconstruction algorithm and summarizes its performance tested with Monte Carlo events under two different containment conditions. The advantages of the new reconstruction are discussed in comparison with reconstructions that use IceTop or in-ice data separately. Some possible improvements are also summarized.

astro-ph.HE↗

High-Energy Galactic Cosmic Rays (Astro2020 Science White Paper)

The origin of the highest energy Galactic cosmic rays is still not understood, nor is the transition to EeV extragalactic particles. Scientific progress requires enhancements of existing air-shower arrays, such as: IceCube with its surface detector IceTop, and the low-energy extensions of both the Telescope Array and the Pierre Auger Observatory.

astro-ph.HE↗