1,177 research outputs found
Results and Perspectives of the Auger Engineering Radio Array
The Auger Engineering Radio Array (AERA) is an extension of the Pierre Auger
Cosmic-Ray Observatory. It is used to detect radio emission from extensive air
showers with energies beyond eV in the MHz frequency band.
After three phases of deployment, AERA now consists of more than 150 autonomous
radio stations with different spacings, covering an area of about km.
It is located at the same site as other Auger low-energy detector extensions
enabling combinations with various other measurement techniques. The radio
array allows different technical schemes to be explored as well as
cross-calibration of our measurements with the established baseline detectors
of the Auger Observatory. We report on the most recent technological
developments and give an overview of the experimental results obtained with
AERA. In particular, we will present the measurement of the radiation energy,
i.e., the amount of energy that is emitted by the air shower in the form of
radio emission, and its dependence on the cosmic-ray energy by comparing with
the measurement of the the well-calibrated Auger surface detector. Furthermore,
we outline the relevance of this result for the absolute calibration of the
energy scale of cosmic-ray observatories.Comment: To be published in the Proceedings of the ARENA2016 conference,
Groningen, The Netherland
ARIANNA: Measurement of cosmic rays with a radio neutrino detector in Antarctica
The ARIANNA detector aims to detect neutrinos with energies above
\SI{e16}{eV} by instrumenting 0.5 Teratons of ice with a surface array of a
thousand independent radio detector stations in Antarctica. The Antarctic ice
is transparent to the radio signals caused by the Askaryan effect which allows
for a cost-effective instrumentation of large volumes. Several pilot stations
are currently operating successfully at the Moore's Bay site (Ross Ice Shelf)
and at the South Pole. As the ARIANNA detector stations are positioned at the
surface, the more abundant cosmic-ray air showers are also measured and serve
as a direct way to prove the capabilities of the detector. We will present
measured cosmic rays and will show how the incoming direction, polarization and
electric field of the cosmic-ray pulse can be reconstructed from single
detector stations comprising 4 upward and 4 downward facing LPDA antennas.Comment: Proceedings of the 8th International Conference on Acoustic and Radio
EeV Neutrino Detection Activities, ARENA 201
Reconstructing the cosmic-ray energy from the radio signal measured in one single station
Short radio pulses can be measured from showers of both high-energy cosmic
rays and neutrinos. While commonly several antenna stations are needed to
reconstruct the energy of an air shower, we describe a novel method that relies
on the radio signal measured in one antenna station only. Exploiting a broad
frequency bandwidth of MHz, we obtain a statistical energy resolution
of better than 15\% on a realistic Monte Carlo set. This method is both a step
towards energy reconstruction from the radio signal of neutrino induced
showers, as well as a promising tool for cosmic-ray radio arrays. Especially
for hybrid arrays where the air shower geometry is provided by an independent
detector, this method provides a precise handle on the energy of the shower
even with a sparse array
Acceleration by Strong Interactions
Beyond the attractive strong potential needed for hadronic bound states,
strong interactions are predicted to provide repulsive forces depending on the
color charges involved. The repulsive interactions could in principle serve for
particle acceleration with highest gradients in the order of GeV/fm. Indirect
evidence for repulsive interactions have been reported in the context of heavy
meson production at colliders. In this contribution, we sketch a thought
experiment to directly investigate repulsive strong interactions. For this we
prepare two quarks using two simultaneous deep inelastic scattering processes
off an iron target. We discuss the principle setup of the experiment and
estimate the number of electrons on target required to observe a repulsive
effect between the quarks.Comment: 6 pages, 7 figure
Modelling uncertainty of the radiation energy emitted by extensive air showers
Recently, the energy determination of extensive air showers using radio
emission has been shown to be both precise and accurate. In particular, radio
detection offers the opportunity for an independent measurement of the absolute
energy of cosmic rays, since the radiation energy (the energy radiated in the
form of radio signals) can be predicted using first-principle calculations
involving no free parameters, and the measurement of radio waves is not subject
to any significant absorption or scattering in the atmosphere. Here, we verify
the implementation of radiation-energy calculations from microscopic simulation
codes by comparing Monte Carlo simulations made with the two codes CoREAS and
ZHAireS. To isolate potential differences in the radio-emission calculation
from differences in the air-shower simulation, the simulations are performed
with equivalent settings, especially the same model for the hadronic
interactions and the description of the atmosphere. Comparing a large set of
simulations with different primary energies and shower directions we observe
differences amounting to a total of only 3.3 %. This corresponds to an
uncertainty of only 1.6 % in the determination of the absolute energy scale and
thus opens the potential of using the radiation energy as an accurate
calibration method for cosmic ray experiments.Comment: 8 pages, 2 figures, ICRC2017 contributio
Determination of the absolute energy scale of extensive air showers via radio emission: systematic uncertainty of underlying first-principle calculations
Recently, the energy determination of extensive air showers using radio
emission has been shown to be both precise and accurate. In particular, radio
detection offers the opportunity for an independent measurement of the absolute
energy scale of cosmic rays, since the radiation energy (the energy radiated in
the form of radio signals) can be predicted using first-principle calculations
involving no free parameters, and the measurement of radio waves is not subject
to any significant absorption or scattering in the atmosphere. To quantify the
uncertainty associated with such an approach, we collate the various
contributions to the uncertainty, and we verify the consistency of
radiation-energy calculations from microscopic simulation codes by comparing
Monte Carlo simulations made with the two codes CoREAS and ZHAireS. We compare
a large set of simulations with different primary energies and shower
directions and observe differences in the radiation energy prediction for the
30 - 80 MHz band of 5.2 %. This corresponds to an uncertainty of 2.6 % for the
determination of the absolute cosmic-ray energy scale. Our result has general
validity and can be built upon directly by experimental efforts for the
calibration of the cosmic-ray energy scale on the basis of radio emission
measurements.Comment: 22 pages, 3 figures, accepted for publication in Astroparticle
Physic
A tree extension for CoNLL-RDF
The technological bridges between knowledge graphs and natural language processing are of utmost importance for the future development of language technology. CoNLL-RDF is a technology that provides such a bridge for popular one-word-per-line formats as widely used in NLP (e.g., the CoNLL Shared Tasks), annotation (Universal Dependencies, Unimorph), corpus linguistics (Corpus WorkBench, CWB) and digital lexicography (SketchEngine): Every empty-line separated table (usually a sentence) is parsed into an graph, can be freely manipulated and enriched using W3C-standardized RDF technology, and then be serialized back into in a TSV format, RDF or other formats. An important limitation is that CoNLL-RDF provides native support for word-level annotations only. This does include dependency syntax and semantic role annotations, but neither phrase structures nor text structure. We describe the extension of the CoNLL-RDF technology stack for two vocabulary extensions of CoNLL-TSV, the PTB bracket notation used in earlier CoNLL Shared Tasks and the extension with XML markup elements featured by CWB and SketchEngine. In order to represent the necessary extensions of the CoNLL vocabulary in an adequate fashion, we employ the POWLA vocabulary for representing and navigating in tree structures
An improved trigger for Askaryan radio detectors
High-energy neutrinos with energies above a few eV can be measured
efficiently with in-ice radio detectors which complement optical detectors such
as IceCube at higher energies. Several pilot arrays explore the radio
technology successfully in Antarctica. Because of the low flux and interaction
cross-section of neutrinos it is vital to increase the sensitivity of the radio
detector as much as possible. In this manuscript, different approaches to
trigger on high-energy neutrinos are systematically studied and optimized. We
find that the sensitivity can be improved substantially (by more than 50%
between eV and eV) by simply restricting the bandwidth in the
trigger to frequencies between 80 MHz and 200 MHz instead of the currently used
80 MHz to ~1 GHz bandwidth. We also compare different trigger schemes that are
currently being used (a simple amplitude threshold, a high/low threshold
trigger and a power-integration trigger) and find that the scheme that performs
best depends on the dispersion of the detector. These findings inform the
detector design of future Askaryan detectors and can be used to increase the
sensitivity to high-energy neutrinos significantly without any additional
costs. The findings also apply to the phased array trigger concept.Comment: Replaced with published versio
An ontology for CoNLL-RDF: formal data structures for TSV formats in language technology
In language technology and language sciences, tab-separated values (TSV) represent a frequently used formalism to represent linguistically annotated natural language, often addressed as "CoNLL formats". A large number of such formats do exist, but although they share a number of common features, they are not interoperable, as different pieces of information are encoded differently in these dialects.
CoNLL-RDF refers to a programming library and the associated data model that has been introduced to facilitate processing and transforming such TSV formats in a serialization-independent way. CoNLL-RDF represents CoNLL data, by means of RDF graphs and SPARQL update operations, but so far, without machine-readable semantics, with annotation properties created dynamically on the basis of a user-defined mapping from columns to labels. Current applications of CoNLL-RDF include linking between corpora and dictionaries [Mambrini and Passarotti, 2019] and knowledge graphs [Tamper et al., 2018], syntactic parsing of historical languages [Chiarcos et al., 2018; Chiarcos et al., 2018], the consolidation of syntactic and semantic annotations [Chiarcos and Fäth, 2019], a bridge between RDF corpora and a traditional corpus query language [Ionov et al., 2020], and language contact studies [Chiarcos et al., 2018].
We describe a novel extension of CoNLL-RDF, introducing a formal data model, formalized as an ontology. The ontology is a basis for linking RDF corpora with other Semantic Web resources, but more importantly, its application for transformation between different TSV formats is a major step for providing interoperability between CoNLL formats
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