Bibli

Using data collected at the Pierre Auger Observatory during the past 3.7 years, we demonstrated a correlation between the arrival directions of cosmic rays with energy above ~ 6x10^{19} electron volts and the positions of active galactic nuclei (AGN) lying within ~ 75 megaparsecs. We rejected the hypothesis of an isotropic distribution of these cosmic rays with at least a 99% confidence level from a prescribed a priori test. The correlation we observed is compatible with the hypothesis that the highest energy particles originate from nearby extragalactic sources whose flux has not been substantially reduced by interaction with the cosmic background radiation. AGN or objects having a similar spatial distribution are possible sources.

We present the results of an analysis of data recorded at the Pierre Auger Observatory in which we search for groups of directionally-aligned events (or 'multiplets') which exhibit a correlation between arrival direction and the inverse of the energy. These signatures are expected from sets of events coming from the same source after having been deflected by intervening coherent magnetic fields. The observation of several events from the same source would open the possibility to accurately reconstruct the position of the source and also measure the integral of the component of the magnetic field orthogonal to the trajectory of the cosmic rays. We describe the largest multiplets found and compute the probability that they appeared by chance from an isotropic distribution. We find no statistically significant evidence for the presence of multiplets arising from magnetic deflections in the present data.

The Pierre Auger Observatory is a detector for ultra-high energy cosmic rays. It consists of a surface array to measure secondary particles at ground level and a fluorescence detector to measure the development of air showers in the atmosphere above the array. The "hybrid" detection mode combines the information from the two subsystems. We describe the determination of the hybrid exposure for events observed by the fluorescence telescopes in coincidence with at least one water-Cherenkov detector of the surface array. A detailed knowledge of the time dependence of the detection operations is crucial for an accurate evaluation of the exposure. We discuss the relevance of monitoring data collected during operations, such as the status of the fluorescence detector, background light and atmospheric conditions, that are used in both simulation and reconstruction.

The Pierre Auger Collaboration has reported evidence for anisotropy in the distribution of arrival directions of the cosmic rays with energies $E>E_{th}=5.5\times 10^{19}$ eV. These show a correlation with the distribution of nearby extragalactic objects, including an apparent excess around the direction of Centaurus A. If the particles responsible for these excesses at $E>E_{th}$ are heavy nuclei with charge $Z$, the proton component of the sources should lead to excesses in the same regions at energies $E/Z$. We here report the lack of anisotropies in these directions at energies above $E_{th}/Z$ (for illustrative values of $Z=6,\ 13,\ 26$). If the anisotropies above $E_{th}$ are due to nuclei with charge $Z$, and under reasonable assumptions about the acceleration process, these observations imply stringent constraints on the allowed proton fraction at the lower energies.

Traditional façade systems are at the point where the minimum comfort guarantees have peaked, showing hygrothermic performance deficiencies which result in higher heating consumption, which is why it´s necessary to make improvements in design and building construction, especially in envelopes, for which efficient building enclosures should be used, generating notable benefits. For these reasons, the study of new façade construction systems is essential, particularly light multi-layers, which offer favorable characteristics for energy consumption savings. With this background, the main aim of this study is to generate knowledge to find out to what extent light multi-layered façades are better, determining which façades are the most efficient and guarantee the comfort conditions of a building, contributing in this way to energy consumption savings. To carry out this study, a methodology of analysis shall be used, signifying that in the first phase a theoretical study has been made, analyzing different configurations of the sample façades, to obtain their thermal performance, using two different methods, thermographic and thermal, obtaining in the thermographic study: surface temperatures of the façades, while in the thermal simulation, generating isotherms, heat flows, data on thermal coupling coefficients to calculate the value of the thermal transmittance and surface conditions, among others. Therefore, using this data, the conclusion has been reached that comparing a traditional enclosure to a light multi-layered one of equal thickness, an improvement of 65% can be achieved in the thermal transmittance, which signifies a saving in energy consumption, exceeding the Technical Building Code.