The Fluorescence Detector of the Pierre Auger Observatory measures the atmospheric depth, X sub(max), 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 X sub(max)-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.
The characteristics of extensive air showers are sensitive to the details of hadronic interactions at energies and in kinematic regions beyond those tested by human-made accelerators. Uncertainties ...on extrapolations of the hadronic interaction models in these regions hamper the interpretation of the ultra high energy cosmic ray data in terms of primary mass composition. We report on how the Pierre Auger Observatory is able to constrain the hadronic interaction models by measuring the muon content and muon production depth of air showers and also by measuring the proton-air cross section for particle production at a center-of-mass energy per nucleon of 57 TeV.
► Xmax is the most common observable for the inference of the mass of UHECR. ► 〈Xmax〉 is linear with 〈lnA〉 in ideal conditions. ► Current experimental observations seem to disagree at the highest ...energies. ► The acceptance of the fluorescence telescopes modifies the Xmax distributions. ► A non-linearity between 〈lnA〉 and 〈Xmax〉 might be present in a given setup.
The measurement of the average depth of the shower maximum is the most commonly used observable for the possible inference of the primary cosmic-ray mass composition. Currently, different experimental Collaborations process and present their data not in the same way, leading to problems in the comparability and interpretation of the results. Whereas 〈Xmax〉 is expected to be proportional to 〈lnA〉 in ideal conditions, we demonstrate that the finite field-of-view of fluorescence telescopes plus the attenuation in the atmosphere introduce a non-linearity into this relation, which is specific for each particular detector setup.
Aims The E101K mutation in the alpha-cardiac actin gene (ACTC) has been associated with apical hypertrophic cardiomyopathy (HCM). As prominent trabeculations were described in some carriers, we ...screened for the E101K mutation in our index patients with HCM, dilated cardiomyopathy (DCM), or left ventricular non-compaction (LVNC). Methods and results Clinical, echocardiographic, and genetic screening by restriction fragment length polymorphism of the ACTC E101K mutation in 247 families with HCM, DCM, or LVNC. The mutation was found in five index patients (one with LVNC and four with HCM). Clinical and morphological data were obtained from 94 family members. Forty-six individuals had cardiomyopathy (43 with the mutation and three with no genetic study): 23 fulfilled criteria for LVNC, 22 were diagnosed as apical HCM, and one had been diagnosed as restrictive cardiomyopathy. There had been one heart transplant and one congestive heart failure death in patients with severe diastolic dysfunction, and five premature sudden deaths. The E101K mutation was not found in 48 unaffected relatives. Septal defects (eight atrial and one ventricular) were found in nine mutant carriers from four families, and were absent in relatives without the mutation (P = 0.003). Conclusion LVNC and HCM may appear as overlapping entities. The ACTC E101K mutation should be considered in the genetic diagnosis of LVNC, apical HCM, and septal defects.
The present white paper is submitted as part of the “Snowmass” process to help inform the long-term plans of the United States Department of Energy and the National Science Foundation for high-energy ...physics. It summarizes the science questions driving the Ultra-High-Energy Cosmic-Ray (UHECR) community and provides recommendations on the strategy to answer them in the next two decades.
Surface detector arrays are designed to measure the spectrum and composition of high energy cosmic rays by detecting the secondary particle flux of the extensive air showers (EAS) induced by the ...primary cosmic rays. Electromagnetic particles and muons constitute the dominant contribution to the ground detector signals. In this paper, we show that the ground signal deposit of an EAS can be described in terms of only very few parameters: the primary energy
E, the zenith angle
θ
, the distance of the shower maximum
X
max
to the ground, and a muon flux normalization
N
μ
. This set of physical parameters is sufficient to predict the average particle fluxes at ground level to around 10% accuracy. We show that this is valid for hadronic air showers, using the two standard hadronic interaction models used in cosmic ray physics, QGSJetII and Sibyll, and for hadronic primaries from protons to iron. Based on this model, a new approach to calibrating the energy scale of ground array experiments is developed, which factors out the model dependence inherent in such calibrations up to now. Additionally, the method yields a measurement of the average number of muons in EAS. The measured distribution of
N
μ
of cosmic ray air showers can then be analysed, in conjunction with measurements of
X
max
from fluorescence detectors, to put constraints on the cosmic ray composition and hadronic interaction models.
The present white paper is submitted as part of the "Snowmass" process to help inform the long-term plans of the United States Department of Energy and the National Science Foundation for high-energy ...physics. Further, it summarizes the science questions driving the Ultra-High-Energy Cosmic-Ray (UHECR) community and provides recommendations on the strategy to answer them in the next two decades.
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