Papers by Jesus Alvarez-Castillo
Journal of Atmospheric and Solar-Terrestrial Physics, 2010
We studied the effect of thunderstorms (TS) in the intensity variations of the electromagnetic an... more We studied the effect of thunderstorms (TS) in the intensity variations of the electromagnetic and muon components of the Cosmic Rays during the year 2004, a year of minimum solar activity. We analyzed the variations in the counting rates of the upper and lower scintillators of the muon telescope installed in Mexico City at times of reported TS and compared those with variations during quiet times. The data were filtered to eliminate long trends, then a wavelet spectrum was calculated, searching for the temporal evolution of diverse periods of high significance; recurrent periodicities and total power distributions were obtained. The results show variations of short period whose main periodicities are arranged in a distribution where the most important are the shortest periodicities. These may be associated to the electric fields of the TS. Significant long period variations were found too, these could be due to other processes linked to rainstorms. No systematic effect on the power of variations due to TS was found.
Methodology for the Study of Atmospheric Effects in the Pierre Auger Observatory
40th COSPAR Scientific Assembly, 2014
Effects of thunderstorms in the electromagnetic component of the cosmic rays observed with the Pierre Auger Observatory, Argentina
38th COSPAR Scientific Assembly, 2010
We studied the effects of thunderstorms (TS) in the intensity variations of the electromagnetic c... more We studied the effects of thunderstorms (TS) in the intensity variations of the electromagnetic component of the secondary cosmic rays observed with the surface detector of the Southern Pierre Auger Observatory during the year 2008, a year of minimum solar activity. We analyzed the variations in the counting rates at times of reported TS and compared those with variations during
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Journal of Cosmology and Astroparticle Physics, 2018
Bounds of the density of sources of ultra-high energy cosmic rays from the Pierre Auger Observatory
Journal of Cosmology and Astroparticle Physics
Journal of Cosmology and Astroparticle Physics, 2013
To interpret the mean depth of cosmic ray air shower maximum and its dispersion, we parametrize t... more To interpret the mean depth of cosmic ray air shower maximum and its dispersion, we parametrize those two observables as functions of the first two moments of the ln A distribution. We examine the goodness of this simple method through simulations of test mass distributions. The application of the parameterization to Pierre Auger Observatory data allows one to study the energy dependence of the mean ln A and of its variance under the assumption of selected hadronic interaction models. We discuss possible implications of these dependences in term of interaction models and astrophysical cosmic ray sources.
Effects of thunderstorms in the electromagnetic component of the cosmic rays observed with the Pierre Auger Observatory, Argentina
We studied the effects of thunderstorms (TS) in the intensity variations of the electromagnetic c... more We studied the effects of thunderstorms (TS) in the intensity variations of the electromagnetic component of the secondary cosmic rays observed with the surface detector of the Southern Pierre Auger Observatory during the year 2008, a year of minimum solar activity. We analyzed the variations in the counting rates at times of reported TS and compared those with variations during
The effects of thunderstorms on the electromagnetic and muon components of the cosmic ray seconda... more The effects of thunderstorms on the electromagnetic and muon components of the cosmic ray secondary flux were studied during severe storms obtained in 2004, analyzing the variations of the counting rates shown in the upper and lower scintillators of the muon telescope installed in Mexico City and considering the data of storms report for the international airport of Mexico City.
Contributions of the Pierre Auger Collaboration to the 33rd International Cosmic Ray Conference, ... more Contributions of the Pierre Auger Collaboration to the 33rd International Cosmic Ray Conference, Rio de Janeiro, Brazil, July 2013
Journal of Cosmology and Astroparticle Physics, 2020
We search for signals of magnetically-induced effects in the arrival directions of ultra-high-ene... more We search for signals of magnetically-induced effects in the arrival directions of ultra-high-energy cosmic rays detected at the Pierre Auger Observatory. We apply two different methods. One is a search for sets of events that show a correlation between their arrival direction and the inverse of their energy, which would be expected if they come from the same point-like source, they have the same electric charge and their deflection is relatively small and coherent. We refer to these sets of events as "multiplets". The second method, called "thrust", is a principal axis analysis aimed to detect the elongated patterns in a region of interest. We study the sensitivity of both methods using a benchmark simulation and we apply them to data in two different searches. The first search is done assuming as source candidates a list of nearby active galactic nuclei and starburst galaxies. The second is an all-sky blind search. We report the results and we find no statistically significant features. We discuss the compatibility of these results with the indications on the mass composition inferred from data of the Pierre Auger Observatory.
Journal of Instrumentation, 2020
Physical Review Letters, 2020
We report a measurement of the energy spectrum of cosmic rays above 2.5 × 10 18 eV based on 215 0... more We report a measurement of the energy spectrum of cosmic rays above 2.5 × 10 18 eV based on 215 030 events. New results are presented: at about 1.3 × 10 19 eV, the spectral index changes from Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
Journal of Instrumentation, 2020
Extensive air showers, originating from ultra-high energy cosmic rays, have been successfully mea... more Extensive air showers, originating from ultra-high energy cosmic rays, have been successfully measured through the use of arrays of water-Cherenkov detectors (WCDs). Sophisticated analyses exploiting WCD data have made it possible to demonstrate that shower simulations, based on different hadronic-interaction models, cannot reproduce the observed number of muons at the ground. The accurate knowledge of the WCD response to muons is paramount in establishing the exact level of this discrepancy. In this work, we report on a study of the response of a WCD of the Pierre Auger Observatory to atmospheric muons performed with a hodoscope made of resistive plate chambers (RPCs), enabling us to select and reconstruct nearly 600 thousand single muon trajectories with zenith angles ranging from 0 • to 55 •. Comparison of distributions of key observables between the hodoscope data and the predictions of dedicated simulations allows us to demonstrate the accuracy of the latter at a level of 2%. As the WCD calibration is based on its response to atmospheric muons, the hodoscope data are also exploited to show the long-term stability of the procedure. K : Large detector systems for particle and astroparticle physics, Data processing methods, Large detector-systems performance, Performance of High Energy Physics Detectors
The Astrophysical Journal, 2020
We present measurements of the large-scale cosmic-ray (CR) anisotropies in R.A., using data colle... more We present measurements of the large-scale cosmic-ray (CR) anisotropies in R.A., using data collected by the surface detector array of the Pierre Auger Observatory over more than 14 yr. We determine the equatorial dipole component,d , through a Fourier analysis in R.A. that includes weights for each event so as to account for the main detector-induced systematic effects. For the energies at which the trigger efficiency of the array is small, the "east-west" method is employed. Besides using the data from the array with detectors separated by 1500m, we also include data from the smaller but denser subarray of detectors with 750m separation, which allows us to extend the analysis down to ∼0.03EeV. The most significant equatorial dipole amplitude obtained is that in the cumulative bin above 8EeV, =-+ d 6.0 0.9 1.0 %, which is inconsistent with isotropy at the 6σ level. In the bins below 8EeV, we obtain 99% CL upper bounds on d ⊥ at the level of 1%-3%. At energies below 1EeV, even though the amplitudes are not significant, the phases determined in most of the bins are not far from the R.A. of the Galactic center, at α GC =−94°, suggesting a predominantly Galactic origin for anisotropies at these energies. The reconstructed dipole phases in the energy bins above 4EeV point instead to R.A. that are almost opposite to the Galactic center one, indicative of an extragalactic CR origin. Unified Astronomy Thesaurus concepts: Cosmic rays (329); Cosmic ray sources (328); Cosmic ray astronomy (324)
Journal of Cosmology and Astroparticle Physics, 2019
Neutrinos with energies above 10 17 eV are detectable with the Surface Detector Array of the Pier... more Neutrinos with energies above 10 17 eV are detectable with the Surface Detector Array of the Pierre Auger Observatory. The identification is efficiently performed for neutrinos of all flavors interacting in the atmosphere at large zenith angles, as well as for Earth-skimming τ neutrinos with nearly tangential trajectories relative to the Earth. No neutrino candidates were found in ∼ 14.7 years of data taken up to 31 August 2018. This leads to restrictive upper bounds on their flux. The 90% C.L. single-flavor limit to the diffuse flux of ultra-high-energy neutrinos with an E −2 ν spectrum in the energy range 1.0 × 10 17 eV − 2.5 × 10 19 eV is E 2 dN ν /dE ν < 4.4 × 10 −9 GeV cm −2 s −1 sr −1 , placing strong constraints on several models of neutrino production at EeV energies and on the properties of the sources of ultra-high-energy cosmic rays.
Journal of Instrumentation, 2017
An in-situ calibration of a logarithmic periodic dipole antenna with a frequency coverage of 30 M... more An in-situ calibration of a logarithmic periodic dipole antenna with a frequency coverage of 30 MHz to 80 MHz is performed. Such antennas are part of a radio station system used for detection of cosmic ray induced air showers at the Engineering Radio Array of the Pierre Auger Observatory, the so-called Auger Engineering Radio Array (AERA). The directional and frequency characteristics of the broadband antenna are investigated using a remotely piloted aircraft carrying a small transmitting antenna. The antenna sensitivity is described by the vector effective length relating the measured voltage with the electric-field components perpendicular to the incoming signal direction. The horizontal and meridional components are determined with an overall uncertainty of 7.4 +0.9 −0.3 % and 10.3 +2.8 −1.7 % respectively. The measurement is used to correct a simulated response of the frequency and directional response of the antenna. In addition, the influence of the ground conductivity and permittivity on the antenna response is simulated. Both have a negligible influence given the ground conditions measured at the detector site. The overall uncertainties of the vector effective length components result in an uncertainty of 8.8 +2.1 −1.3 % in the square root of the energy fluence for incoming signal directions with zenith angles smaller than 60 • .
Frontiers in Astronomy and Space Sciences, 2019
An overview of the multi-messenger capabilities of the Pierre Auger Observatory is presented. The... more An overview of the multi-messenger capabilities of the Pierre Auger Observatory is presented. The techniques and performance of searching for Ultra-High Energy neutrinos, photons and neutrons are described. Some of the most relevant results are reviewed, such as stringent upper bounds that were placed to a flux of diffuse cosmogenic neutrinos and photons, bounds placed on neutrinos emitted from compact binary mergers that were detected by LIGO and Virgo during their first and second observing runs, as well as searches for high energy photons and neutrons from the Galactic center that constrain the properties of the putative Galactic PeVatron, observed by the H.E.S.S. collaboration. The observation of directional correlations between ultra-high energy cosmic rays and either high energy astrophysical neutrinos or specific source populations, weighted by their electromagnetic radiation, are also discussed. They constitute additional multi-messenger approaches aimed at identifying the sources of high energy cosmic rays.
Science, 2017
High-energy particles are extragalactic Cosmic rays are high-energy particles arriving from space... more High-energy particles are extragalactic Cosmic rays are high-energy particles arriving from space; some have energies far beyond those that human-made particle accelerators can achieve. The sources of higher-energy cosmic rays remain under debate, although we know that lower-energy cosmic rays come from the solar wind. The Pierre Auger Collaboration reports the observation of thousands of cosmic rays with ultrahigh energies of several exa–electron volts (about a Joule per particle), arriving in a slightly dipolar distribution (see the Perspective by Gallagher and Halzen). The direction of the rays indicates that the particles originated in other galaxies and not from nearby sources within our own Milky Way Galaxy. Science , this issue p. 1266 ; see also p. 1240
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Papers by Jesus Alvarez-Castillo