We present a summary of recent tests and measurements of hadronic interaction properties with air showers. This report has a special focus on muon density measurements. Several experiments reported ...deviations between simulated and recorded muon densities in extensive air showers, while others reported no discrepancies. We combine data from eight leading air shower experiments to cover shower energies from PeV to tens of EeV. Data are combined using the
z
-scale, a unified reference scale based on simulated air showers. Energy-scales of experiments are cross-calibrated. Above 10 PeV, we find a muon deficit in simulated air showers for each of the six considered hadronic interaction models. The deficit is increasing with shower energy. For the models EPOS-LHC and QGSJet-II.04, the slope is found significant at 8 sigma.
We have studied how the energy spectrum of muons at production affects some of the most common measurements related to muons in extensive air shower studies, namely, the number of muons at the ...ground, the slope of the lateral distribution of muons, the apparent muon production depth, and the arrival time delay of muons at ground. We found that by changing the energy spectrum by an amount consistent with the difference between current models (namely EPOS-LHC and QGSJet-II.04), the muon surface density at ground increases 5% at 20° zenith angle and 17% at 60° zenith angle. This effect introduces a zenith angle dependence on the reconstructed number of muons which might be experimentally observed. The maximum of the muon production depth distribution at 40° increases ∼ 10 g/cm2 and ∼ 0 g/cm2 at 60°, which, from pure geometrical considerations, increases the arrival time delay of muons. There is an extra contribution to the delay due to the subluminal velocities of muons of the order of ∼ 3 ns at all zenith angles. Finally, changes introduced in the logarithmic slope of the lateral density function are less than 2%.
► We describe a model to propagate the muons in extensive air showers. ► The few relevant distributions at production are identified. ► Energy, Pt and depth at production are related to the ...distributions at ground. ► This model can be used for fast simulations. ► This model can be used to experimentally assess the distributions at production.
In this article we identify the key elements that govern the propagation of muons from the production in extensive air showers to ground. We describe a model based on simple assumptions that propagates the muons starting from the few relevant distributions at production. We compare the results to the ground distributions given by a full air shower Monte Carlo. This study is motivated by the need of modeling the muon component in extensive air showers with the goal of experimentally reconstructing their distributions at production, which act as a footprint of the hadronic cascade.
Peanut smut, caused by Thecaphora frezii, increased its incidence and prevalence in the main growing region of Argentina in the last decade becoming the main peanut disease. Despite this fact, ...growers continue producing peanut without any disease management strategy, which is leading to a local accumulation of T. frezii inoculum. The goal of the present study was to assess the efficacy of 12 fungicides in controlling T. frezii. For this purpose, in vitro assays, pot, and field experiments were performed during 2014/15 and 2015/16. In vitro assays classified the fungicides regarding their capacity to inhibit T. frezii mycelium growth as: thiophanate-methyl – not fungitoxic (EC50 > 100); mancozeb – moderately fungitoxic (EC50 = 6.28); difenoconazole, propiconazole, cyproconazole, tebuconazole, picoxystrobin, azoxystrobin, kresoxim-methyl, pyraclostrobin, penthiopyrad, and chlorothalonil – highly fungitoxic (EC50 < 0.1). Azoxystrobin showed the highest control levels in pot experiments: 58.9% (2014/15) and 92% (2015/16). The greatest control efficiency in field experiments was observed for cyproconazole in 2015 and azoxystrobin in 2016, reducing peanut smut by 47.7% and 39.5%, respectively. Based on our results, chemical control can be considered as a moderately efficient practice which may complement the cultivar genetic resistance and cultural practices in an integrated approach for managing peanut smut.
•We evaluated the performance of 12 fungicides against peanut smut in Argentina.•Cyproconazole and azoxystrobin had the highest control.•In vitro mycelial growth inhibition and disease control presented low correlation.•The results can be considered in an integrated approach for managing peanut smut.
Extensive Air Showers are complex macroscopic objects initiated by single ultra-high energy particles. They are the result of millions of high energy reactions in the atmosphere and can be described ...as the superposition of hadronic and electromagnetic cascades. The hadronic cascade is the air shower backbone, and it is mainly made of pions. Decays of neutral pions initiate electromagnetic cascades, while the decays of charged pions produce muons which leave the hadronic core and travel many kilometers almost unaffected. Muons are smoking guns of the hadronic cascade: the energy, transverse momentum, spatial distribution and depth of production are key to reconstruct the history of the air shower. In this work, we overview the phenomenology of muons on the air shower and Its relation to the hadronic cascade. We briefly review the experimental efforts to analyze muons within air showers and discuss possible paths to use this Information.
A new concept for the direct measurement of muons in air showers is presented. The concept is based on resistive plate chambers (RPCs), which can directly measure muons with very good space and time ...resolution. The muon detector is shielded by placing it under another detector able to absorb and measure the electromagnetic component of the showers such as a water-Cherenkov detector, commonly used in air shower arrays. The combination of the two detectors in a single, compact detector unit provides a unique measurement that opens rich possibilities in the study of air showers.
► The muonic longitudinal profile at production is characterized. ► The shape of the muon production profile displays an universal behaviour. ► New mass composition variables are studied. ► Shape and ...maxima of EM and muonic profile correlates.
In this paper the longitudinal profile of muon production along the shower axis is studied. The characteristics of this distribution is investigated for different primary masses, zenith angles, primary energies, and different high energy hadronic interaction models. It is found that the shape of this distribution displays universal features similar to what is known for the electromagnetic profile. The relation between the muon production distribution and the longitudinal electromagnetic evolution is also discussed.
The Fluorescence Detector of the Pierre Auger Observatory measures the atmospheric depth, Xmax, where the longitudinal profile of the high energy air showers reaches its maximum. This is sensitive to ...the nuclear mass composition of the cosmic rays. Due to its hybrid design, the Pierre Auger Observatory also provides independent experimental observables obtained from the Surface Detector for the study of the nuclear mass composition. We present Xmax-distributions and an update of the average and RMS values in different energy bins and compare them to the predictions for different nuclear masses of the primary particles and hadronic interaction models. We also present the results of the composition-sensitive parameters derived from the ground level component.
Extensive air showers are the result of billions of particle reactions initiated by single cosmic rays at ultra-high energy. Their characteristics are sensitive both to the mass of the primary cosmic ...ray and to the fine details of hadronic interactions. Ultra-high energy cosmic rays can be used to experimentally extend our knowledge on hadronic interactions in energy and kinematic regions beyond those tested by human-made accelerators.
We report on how the Pierre Auger Observatory is able to measure the proton-air cross section for particle production at a center-of-mass energy per nucleon of 39 TeV and 56 TeV and also to constrain the new hadronic interaction models tuned after the results of the Large Hadron Collider, by measuring: the average shape of the electromagnetic longitudinal profile of air showers, the moments of the distribution of the depth at which they reach their maximum, and the content and production depth of muons in air showers with a primary center-of-mass energy per nucleon around and above the 100 TeV scale.
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