Natural stone masonry characterization for the shaking-table test of a scaled building specimen

This paper discusses the material characterization tests on stone masonry specimens, and the in-plane cyclic shear-compression tests on four half-scale unreinforced stone masonry piers, which complement a shaking-table test on a half-scale building aggregate prototype. Material characterization tests allowed defining a mortar composition suitable for satisfying the similitude relationships associated with the half-scale tests. Vertical and diagonal compression tests provided a complete description of the mechanical properties of masonry assemblies, while in-plane cyclic shear-compression tests allow determining the hysteretic behavior of masonry piers with different aspect ratios and axial compression levels. Strength and displacement capacities corresponding to the observed damage mechanisms and failure modes were also identified and associated with the specimens geometric and loading conditions. These activities are part of an experimental and numerical research project jointly carried by the University of Pavia, Italy, and the École Polytechnique Fédérale de Lausanne, Switzerland, which aims at assessing the seismic vulnerability of natural stone masonry building aggregates of the historical center of Basel, Switzerland

Measurement of the cosmic ray spectrum above 4×10184{\times}10^{18} eV using inclined events detected with the Pierre Auger Observatory

A measurement of the cosmic-ray spectrum for energies exceeding $4{\times}10^{18}$ eV is presented, which is based on the analysis of showers with zenith angles greater than $60^{\circ}$ detected with the Pierre Auger Observatory between 1 January 2004 and 31 December 2013. The measured spectrum confirms a flux suppression at the highest energies. Above $5.3{\times}10^{18}$ eV, the "ankle", the flux can be described by a power law $E^{-\gamma}$ with index $\gamma=2.70 \pm 0.02 \,\text{(stat)} \pm 0.1\,\text{(sys)}$ followed by a smooth suppression region. For the energy ($E_\text{s}$) at which the spectral flux has fallen to one-half of its extrapolated value in the absence of suppression, we find $E_\text{s}=(5.12\pm0.25\,\text{(stat)}^{+1.0}_{-1.2}\,\text{(sys)}){\times}10^{19}$ eV.Comment: Replaced with published version. Added journal reference and DO

Combined fit to the spectrum and composition data measured by the Pierre Auger Observatory including magnetic horizon effects

The measurements by the Pierre Auger Observatory of the energy spectrum and mass composition of cosmic rays can be interpreted assuming the presence of two extragalactic source populations, one dominating the flux at energies above a few EeV and the other below. To fit the data ignoring magnetic field effects, the high-energy population needs to accelerate a mixture of nuclei with very hard spectra, at odds with the approximate E$^{-2}$ shape expected from diffusive shock acceleration. The presence of turbulent extragalactic magnetic fields in the region between the closest sources and the Earth can significantly modify the observed CR spectrum with respect to that emitted by the sources, reducing the flux of low-rigidity particles that reach the Earth. We here take into account this magnetic horizon effect in the combined fit of the spectrum and shower depth distributions, exploring the possibility that a spectrum for the high-energy population sources with a shape closer to E$^{-2}$ be able to explain the observations