Person:
Rosado Vélez, Jaime

First Name

Jaime

Last Name

Rosado Vélez

URI

https://hdl.handle.net/20.500.14352/75114

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Ciencias Físicas

Department

Estructura de la Materia, Física Térmica y Electrónica

Area

Física Atómica, Molecular y Nuclear

Identifiers

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Now showing 1 - 10 of 54

Constraints on the origin of cosmic rays above 10(18) eV from large-scale anisotropy searches in data of the pierre auger observatory.
(Astrophysical journal letters, 2013) Arganda, E.; Arqueros Martínez, Fernando; Blanco Ramos, Francisco; García Pinto, Diego; Minaya Flores, Ignacio Andrés; Ortiz Ramis, Montserrat; Rosado Vélez, Jaime; Vázquez Peñas, José Ramón
A thorough search for large-scale anisotropies in the distribution of arrival directions of cosmic rays detected above 10(18) eV at the Pierre Auger Observatory is reported. For the first time, these large-scale anisotropy searches are performed as a function of both the right ascension and the declination and expressed in terms of dipole and quadrupole moments. Within the systematic uncertainties, no significant deviation from isotropy is revealed. Upper limits on dipole and quadrupole amplitudes are derived under the hypothesis that any cosmic ray anisotropy is dominated by such moments in this energy range. These upper limits provide constraints on the production of cosmic rays above 10(18) eV, since they allow us to challenge an origin from stationary galactic sources densely distributed in the galactic disk and emitting predominantly light particles in all directions.
Interpretation of the depths of maximum of extensive air showers measured by the Pierre Auger Observatory
(Journal of cosmology and astroparticle physics, 2013) Arqueros Martínez, Fernando; Blanco Ramos, Francisco; García Pinto, Diego; Minaya Flores, Ignacio Andrés; Ortiz Ramis, Montserrat; Rosado Vélez, Jaime; Vázquez Peñas, José Ramón
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.
Energy estimation of cosmic rays with the Engineering Radio Array of the Pierre Auger Observatory
(Physical review D, 2016) Arqueros Martínez, Fernando; García Pinto, Diego; Minaya Flores, Ignacio Andrés; Rosado Vélez, Jaime; Vázquez Peñas, José Ramón
The Auger Engineering Radio Array (AERA) is part of the Pierre Auger Observatory and is used to detect the radio emission of cosmic-ray air showers. These observations are compared to the data of the surface detector stations of the Observatory, which provide well-calibrated information on the cosmic-ray energies and arrival directions. The response of the radio stations in the 30-80 MHz regime has been thoroughly calibrated to enable the reconstruction of the incoming electric field. For the latter, the energy deposit per area is determined from the radio pulses at each observer position and is interpolated using a two-dimensional function that takes into account signal asymmetries due to interference between the geomagnetic and charge-excess emission components. The spatial integral over the signal distribution gives a direct measurement of the energy transferred from the primary cosmic ray into radio emission in the AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air shower arriving perpendicularly to the geomagnetic field. This radiation energy-corrected for geometrical effects-is used as a cosmic-ray energy estimator. Performing an absolute energy calibration against the surface-detector information, we observe that this radio-energy estimator scales quadratically with the cosmic-ray energy as expected for coherent emission. We find an energy resolution of the radio reconstruction of 22% for the data set and 17% for a high-quality subset containing only events with at least five radio stations with signal.
Modeling crosstalk and afterpulsing in silicon photomultipliers
(Nuclear instruments & methods in physics research section A: accelerators spectrometers detectors and associated equipment, 2015) Rosado Vélez, Jaime; Aranda, V. M.; Blanco Ramos, Francisco; Arqueros Martínez, Fernando
An experimental method to characterize the crosstalk and afterpulsing in silicon photomultipliers has been developed and applied to two detectors fabricated by Hamamatsu. An analytical model of optical crosstalk that we presented in a previous publication has been compared with new measurements, confirming our results. Progresses on a statistical model to describe afterpulsing and delayed crosstalk are also shown and compared with preliminary experimental data. (C) 2014 Elsevier B.V. All rights reserved.
Large-scale distribution of arrival directions of cosmic rays detected above 10(18) eV at the Pierre Auger observatory
(Astrophysical journal supplement series, 2012) Arganda, E.; Arqueros Martínez, Fernando; Blanco Ramos, Francisco; García Pinto, Diego; Minaya Flores, Ignacio Andrés; Ortiz Ramis, Montserrat; Rosado Vélez, Jaime; Vázquez Peñas, José Ramón
A thorough search for large-scale anisotropies in the distribution of arrival directions of cosmic rays detected above 10(18) eV at the Pierre Auger Observatory is presented. This search is performed as a function of both declination and right ascension in several energy ranges above 10(18) eV, and reported in terms of dipolar and quadrupolar coefficients. Within the systematic uncertainties, no significant deviation from isotropy is revealed. Assuming that any cosmic-ray anisotropy is dominated by dipole and quadrupole moments in this energy range, upper limits on their amplitudes are derived. These upper limits allow us to test the origin of cosmic rays above 10(18) eV from stationary Galactic sources densely distributed in the Galactic disk and predominantly emitting light particles in all directions.
The fluorescence detector of the Pierre Auger Observatory
(Nuclear instruments & methods in physics research. Section A, Accelerators spectrometers detectors and associated equipment, 2010) Arganda, E.; Arqueros Martínez, Fernando; Blanco Ramos, Francisco; García Pinto, Diego; Monasor, M.; Ortiz Ramis, Montserrat; Ros, G.; Rosado Vélez, Jaime; Vázquez Peñas, José Ramón
The Pierre Auger Observatory is a hybrid detector for ultra-high energy cosmic rays. It combines a surface array to measure secondary particles at ground level together with a fluorescence detector to measure the development of air showers in the atmosphere above the array. The fluorescence detector comprises 24 large telescopes specialized for measuring the nitrogen fluorescence caused by charged particles of cosmic ray air showers. In this paper we describe the components of the fluorescence detector including its optical system, the design of the camera, the electronics, and the systems for relative and absolute calibration. We also discuss the operation and the monitoring of the detector. Finally, we evaluate the detector performance and precision of shower reconstructions. (C) 2010 Elsevier B.V All rights reserved.
Search for patterns by combining cosmic-ray energy and arrival directions at the Pierre Auger Observatory
(European physical journal C, 2015) Aranda, V. M.; Arqueros Martínez, Fernando; García Pinto, Diego; Minaya Flores, Ignacio Andrés; Rosado Vélez, Jaime; Vázquez Peñas, José Ramón
Energy-dependent patterns in the arrival directions of cosmic rays are searched for using data of the Pierre Auger Observatory. We investigate local regions around the highest-energy cosmic rays with E >= 6 x 10(19) eV by analyzing cosmic rays with energies above E >= 5 x 10(18) eV arriving within an angular separation of approximately 15 degrees. We characterize the energy distributions inside these regions by two independent methods, one searching for angular dependence of energy-energy correlations and one searching for collimation of energy along the local system of principal axes of the energy distribution. No significant patterns are found with this analysis. The comparison of these measurements with astrophysical scenarios can therefore be used to obtain constraints on related model parameters such as strength of cosmic-ray deflection and density of point sources.
Nanosecond-level time synchronization of autonomous radio detector stations for extensive air showers
(Journal of instrumentation, 2016) Arqueros Martínez, Fernando; García Pinto, Diego; Minaya Flores, Ignacio Andrés; Rosado Vélez, Jaime; Vázquez Peñas, José Ramón
To exploit the full potential of radio measurements of cosmic-ray air showers at MHz frequencies, a detector timing synchronization within 1 ns is needed. Large distributed radio detector arrays such as the Auger Engineering Radio Array (AERA) rely on timing via the Global Positioning System (GPS) for the synchronization of individual detector station clocks. Unfortunately, GPS timing is expected to have an accuracy no better than about 5 ns. In practice, in particular in AERA, the GPS clocks exhibit drifts on the order of tens of ns. We developed a technique to correct for the GPS drifts, and an independent method is used to cross-check that indeed we reach a nanosecond-scale timing accuracy by this correction. First, we operate a "beacon transmitter" which emits defined sine waves detected by AERA antennas recorded within the physics data. The relative phasing of these sine waves can be used to correct for GPS clock drifts. In addition to this, we observe radio pulses emitted by commercial airplanes, the position of which we determine in real time from Automatic Dependent Surveillance Broadcasts intercepted with a software-defined radio. From the known source location and the measured arrival times of the pulses we determine relative timing offsets between radio detector stations. We demonstrate with a combined analysis that the two methods give a consistent timing calibration with an accuracy of 2 ns or better. Consequently, the beacon method alone can be used in the future to continuously determine and correct for GPS clock drifts in each individual event measured by AERA.
Measurement of the cosmic ray energy spectrum using hybrid events of the Pierre Auger Observatory
(European physical journal plus, 2012) Arganda, E.; Arqueros Martínez, Fernando; Blanco Ramos, Francisco; García Pinto, Diego; Minaya Flores, Ignacio Andrés; Ortiz Ramis, Montserrat; Rosado Vélez, Jaime; Vázquez Peñas, José Ramón
The energy spectrum of ultra-high energy cosmic rays above 10(18)eV is measured using the hybrid events collected by the Pierre Auger Observatory between November 2005 and September 2010. The large exposure of the Observatory allows the measurement of the main features of the energy spectrum with high statistics. Full Monte Carlo simulations of the extensive air showers (based on the CORSIKA code) and of the hybrid detector response are adopted here as an independent cross check of the standard analysis (Phys. Lett. B 685, 239 (2010)). The dependence on mass composition and other systematic uncertainties are discussed in detail and, in the full Monte Carlo approach, a region of confidence for flux measurements is defined when all the uncertainties are taken into account. An update is also reported of the energy spectrum obtained by combining the hybrid spectrum and that measured using the surface detector array.
Prospects for Cherenkov Telescope Array observations of the young supernova remnant RX J1713.7-3946
(Astrophysical journal, 2017) Arqueros Martínez, Fernando; Barrio Uña, Juan Abel; Contreras González, José Luis; Franco Peláez, Francisco Javier; López Moya, Marcos; Mirabal Barrios, Néstor; Nievas Rosillo, Mireia; Rosado Vélez, Jaime; Tejedor Álvarez, Luis Ángel
We perform simulations for future Cherenkov Telescope Array (CTA) observations of RX J1713.7−3946, a young supernova remnant (SNR) and one of the brightest sources ever discovered in very high energy (VHE) gamma rays. Special attention is paid to exploring possible spatial (anti)correlations of gamma rays with emission at other wavelengths, in particular X-rays and CO/H I emission. We present a series of simulated images of RX J1713.7−3946 for CTA based on a set of observationally motivated models for the gamma-ray emission. In these models, VHE gamma rays produced by high-energy electrons are assumed to trace the nonthermal X-ray emission observed by XMM-Newton, whereas those originating from relativistic protons delineate the local gas distributions. The local atomic and molecular gas distributions are deduced by the NANTEN team from CO and H I observations. Our primary goal is to show how one can distinguish the emission mechanism(s) of the gamma rays (i.e., hadronic versus leptonic, or a mixture of the two) through information provided by their spatial distribution, spectra, and time variation. This work is the first attempt to quantitatively evaluate the capabilities of CTA to achieve various proposed scientific goals by observing this important cosmic particle accelerator.