166 research outputs found
Design, upgrade and characterization of the silicon photomultiplier front-end for the AMIGA detector at the Pierre Auger Observatory
AMIGA (Auger Muons and Infill for the Ground Array) is an upgrade of the
Pierre Auger Observatory to complement the study of ultra-high-energy cosmic
rays (UHECR) by measuring the muon content of extensive air showers (EAS). It
consists of an array of 61 water Cherenkov detectors on a denser spacing in
combination with underground scintillation detectors used for muon density
measurement. Each detector is composed of three scintillation modules, with 10
m detection area per module, buried at 2.3 m depth, resulting in a total
detection area of 30 m. Silicon photomultiplier sensors (SiPM) measure the
amount of scintillation light generated by charged particles traversing the
modules. In this paper, the design of the front-end electronics to process the
signals of those SiPMs and test results from the laboratory and from the Pierre
Auger Observatory are described. Compared to our previous prototype, the new
electronics shows a higher performance, higher efficiency and lower power
consumption, and it has a new acquisition system with increased dynamic range
that allows measurements closer to the shower core. The new acquisition system
is based on the measurement of the total charge signal that the muonic
component of the cosmic ray shower generates in the detector.Comment: 40 pages, 33 figure
A basal lithostrotian titanosaur (Dinosauria: Sauropoda) with a complete skull: Implications for the evolution and paleobiology of titanosauria
We describe Sarmientosaurus musacchioi gen. et sp. nov., a titanosaurian sauropod dinosaur from the Upper Cretaceous (Cenomanian - Turonian) Lower Member of the Bajo Barreal Formation of southern Chubut Province in central Patagonia, Argentina. The holotypic and only known specimen consists of an articulated, virtually complete skull and part of the cranial and middle cervical series. Sarmientosaurus exhibits the following distinctive features that we interpret as autapomorphies: (1) maximum diameter of orbit nearly 40% rostrocaudal length of cranium; (2) complex maxilla - lacrimal articulation, in which the lacrimal clasps the ascending ramus of the maxilla; (3) medial edge of caudal sector of maxillary ascending ramus bordering bony nasal aperture with low but distinct ridge; (4) ´tongue-like´ ventral process of quadratojugal that overlaps quadrate caudally; (5) separate foramina for all three branches of the trigeminal nerve; (6) absence of median venous canal connecting infundibular region to ventral part of brainstem; (7) subvertical premaxillary, procumbent maxillary, and recumbent dentary teeth; (8) cervical vertebrae with ´strut-like´ centroprezygapophyseal laminae; (9) extremely elongate and slender ossified tendon positioned ventrolateral to cervical vertebrae and ribs. The cranial endocast of Sarmientosaurus preserves some of the most complete information obtained to date regarding the brain and sensory systems of sauropods. Phylogenetic analysis recovers the new taxon as a basal member of Lithostrotia, as the most plesiomorphic titanosaurian to be preserved with a complete skull. Sarmientosaurus provides a wealth of new cranial evidence that reaffirms the close relationship of titanosaurs to Brachiosauridae. Moreover, the presence of the relatively derived lithostrotian Tapuiasaurus in Aptian deposits indicates that the new Patagonian genus represents a ´ghost lineage´ with a comparatively plesiomorphic craniodental form, the evolutionary history of which is missing for at least 13 million years of the Cretaceous. The skull anatomy of Sarmientosaurus suggests that multiple titanosaurian species with dissimilar cranial structures coexisted in the early Late Cretaceous of southern South America. Furthermore, the new taxon possesses a number of distinctive morphologies - such as the ossified cervical tendon, extremely pneumatized cervical vertebrae, and a habitually downward- facing snout - that have rarely, if ever, been documented in other titanosaurs, thus broadening our understanding of the anatomical diversity of this remarkable sauropod clade. The latter two features were convergently acquired by at least one penecontemporaneous diplodocoid, and may represent mutual specializations for consuming low-growing vegetation.Fil: Martínez, Rubén Darío. Universidad Nacional de la Patagonia; ArgentinaFil: Lamanna, Matthew C.. Carnegie Museum Of Natural History; Estados UnidosFil: Novas, Fernando Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "bernardino Rivadavia"; ArgentinaFil: Ridgely, Ryan C.. Ohio University College Of Osteopathic Medicine; Estados UnidosFil: Casal, Gabriel. Universidad Nacional de la Patagonia; ArgentinaFil: Martínez, Javier E.. Hospital Regional de Comodoro Rivadavia; ArgentinaFil: Vita, Javier R.. Resonancia Magnética Borelli; ArgentinaFil: Witmer, Lawrence M.. Ohio University College Of Osteopathic Medicine; Estados Unido
Extraction of the Muon Signals Recorded with the Surface Detector of the Pierre Auger Observatory Using Recurrent Neural Networks
The Pierre Auger Observatory, at present the largest cosmic-ray observatory
ever built, is instrumented with a ground array of 1600 water-Cherenkov
detectors, known as the Surface Detector (SD). The SD samples the secondary
particle content (mostly photons, electrons, positrons and muons) of extensive
air showers initiated by cosmic rays with energies ranging from eV up
to more than eV. Measuring the independent contribution of the muon
component to the total registered signal is crucial to enhance the capability
of the Observatory to estimate the mass of the cosmic rays on an event-by-event
basis. However, with the current design of the SD, it is difficult to
straightforwardly separate the contributions of muons to the SD time traces
from those of photons, electrons and positrons. In this paper, we present a
method aimed at extracting the muon component of the time traces registered
with each individual detector of the SD using Recurrent Neural Networks. We
derive the performances of the method by training the neural network on
simulations, in which the muon and the electromagnetic components of the traces
are known. We conclude this work showing the performance of this method on
experimental data of the Pierre Auger Observatory. We find that our predictions
agree with the parameterizations obtained by the AGASA collaboration to
describe the lateral distributions of the electromagnetic and muonic components
of extensive air showers.Comment: 23 pages, 15 figures. Version accepted for publication in JINS
Design and implementation of the AMIGA embedded system for data acquisition
The Auger Muon Infill Ground Array (AMIGA) is part of the AugerPrime upgrade
of the Pierre Auger Observatory. It consists of particle counters buried 2.3 m
underground next to the water-Cherenkov stations that form the 23.5 km
large infilled array. The reduced distance between detectors in this denser
area allows the lowering of the energy threshold for primary cosmic ray
reconstruction down to about 10 eV. At the depth of 2.3 m the
electromagnetic component of cosmic ray showers is almost entirely absorbed so
that the buried scintillators provide an independent and direct measurement of
the air showers muon content. This work describes the design and implementation
of the AMIGA embedded system, which provides centralized control, data
acquisition and environment monitoring to its detectors. The presented system
was firstly tested in the engineering array phase ended in 2017, and lately
selected as the final design to be installed in all new detectors of the
production phase. The system was proven to be robust and reliable and has
worked in a stable manner since its first deployment.Comment: Accepted for publication at JINST. Published version, 34 pages, 15
figures, 4 table
Deep-Learning based Reconstruction of the Shower Maximum using the Water-Cherenkov Detectors of the Pierre Auger Observatory
The atmospheric depth of the air shower maximum is an
observable commonly used for the determination of the nuclear mass composition
of ultra-high energy cosmic rays. Direct measurements of are
performed using observations of the longitudinal shower development with
fluorescence telescopes. At the same time, several methods have been proposed
for an indirect estimation of from the characteristics of
the shower particles registered with surface detector arrays. In this paper, we
present a deep neural network (DNN) for the estimation of .
The reconstruction relies on the signals induced by shower particles in the
ground based water-Cherenkov detectors of the Pierre Auger Observatory. The
network architecture features recurrent long short-term memory layers to
process the temporal structure of signals and hexagonal convolutions to exploit
the symmetry of the surface detector array. We evaluate the performance of the
network using air showers simulated with three different hadronic interaction
models. Thereafter, we account for long-term detector effects and calibrate the
reconstructed using fluorescence measurements. Finally, we
show that the event-by-event resolution in the reconstruction of the shower
maximum improves with increasing shower energy and reaches less than
at energies above .Comment: Published version, 29 pages, 12 figure
Direct measurement of the muonic content of extensive air showers between and eV at the Pierre Auger Observatory
The hybrid design of the Pierre Auger Observatory allows for the measurement of the properties of extensive air showers initiated by ultra-high energy cosmic rays with unprecedented precision. By using an array of prototype underground muon detectors, we have performed the first direct measurement, by the Auger Collaboration, of the muon content of air showers between 2×10 and 2×10 eV. We have studied the energy evolution of the attenuation-corrected muon density, and compared it to predictions from air shower simulations. The observed densities are found to be larger than those predicted by models. We quantify this discrepancy by combining the measurements from the muon detector with those from the Auger fluorescence detector at 10eV and 10eV. We find that, for the models to explain the data, an increase in the muon density of 38% ±4%(12%) ± (21%)¦(18%) for EPOS-LHC, and of 50%(53%) ±4%(13%) ± (23%)¦(20%) for QGSJetII-04, is respectively needed
Calibration of the underground muon detector of the Pierre Auger Observatory
To obtain direct measurements of the muon content of extensive air showers with energy above 10 eV, the Pierre Auger Observatory is currently being equipped with an underground muon detector (UMD), consisting of 219 10 m-modules, each segmented into 64 scintillators coupled to silicon photomultipliers (SiPMs). Direct access to the shower muon content allows for the study of both of the composition of primary cosmic rays and of high-energy hadronic interactions in the forward direction. As the muon density can vary between tens of muons per m2 close to the intersection of the shower axis with the ground to much less than one per m2 when far away, the necessary broad dynamic range is achieved by the simultaneous implementation of two acquisition modes in the read-out electronics: the binary mode, tuned to count single muons, and the ADC mode, suited to measure a high number of them. In this work, we present the end-to-end calibration of the muon detector modules: first, the SiPMs are calibrated by means of the binary channel, and then, the ADC channel is calibrated using atmospheric muons, detected in parallel to the shower data acquisition. The laboratory and field measurements performed to develop the implementation of the full calibration chain of both binary and ADC channels are presented and discussed. The calibration procedure is reliable to work with the high amount of channels in the UMD, which will be operated continuously, in changing environmental conditions, for several years
A Catalog of the Highest-energy Cosmic Rays Recorded during Phase I of Operation of the Pierre Auger Observatory
A catalog containing details of the highest-energy cosmic rays recorded through the detection of extensive air-showers at the Pierre Auger Observatory is presented with the aim of opening the data to detailed examination. Descriptions of the 100 showers created by the highest-energy particles recorded between 1 January 2004 and 31 December 2020 are given for cosmic rays that have energies in the range 78 EeV to 166 EeV. Details are also given of a further nine very-energetic events that have been used in the calibration procedure adopted to determine the energy of each primary. A sky plot of the arrival directions of the most energetic particles is shown. No interpretations of the data are offered
Measurement of the fluctuations in the number of muons in extensive air showers with the Pierre Auger Observatory
We present the first measurement of the fluctuations in the number of muons
in extensive air showers produced by ultra-high energy cosmic rays. We find
that the measured fluctuations are in good agreement with predictions from air
shower simulations. This observation provides new insights into the origin of
the previously reported deficit of muons in air shower simulations and
constrains models of hadronic interactions at ultra-high energies. Our
measurement is compatible with the muon deficit originating from small
deviations in the predictions from hadronic interaction models of particle
production that accumulate as the showers develop.Comment: Accepted for publication in PR
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