110 research outputs found
Erratum: Search for photons with energies above 1018 eV using the hybrid detector of the Pierre Auger Observatory
No full textExposure calculation Due to a mistake in the numerical integration following eq. (6.2) of the original article [1], the exposure shown in figure 5 of the original article was incorrect. The correct exposure is shown in figure 1. 2 Upper limits on the integral photon flux and fraction The incorrect exposure affects the calculation of the upper limits on the integral photon flux following eq. (6.1) of the original article. The correct values for the upper limits are 0.038, 0.010, 0.009, 0.008 and 0.007 km−2 sr−1 yr−1 for threshold energies of 1, 2, 3, 5 and 10 EeV. The correct values for the upper limits on the integral photon fraction subsequently derived are 0.14 %, 0.17 %, 0.42 %, 0.86 % and 2.9 % for the same threshold energies. 3 Author list The author list of this erratum also corrects a mistake made in the original article, where F. Zuccarello was missing and Z. Zong was listed twice
Evidence for a mixed mass composition at the ‘ankle’ in the cosmic-ray spectrum
No full textWe report a first measurement for ultrahigh energy cosmic rays of the correlation between the depth of shower maximum and the signal in the water Cherenkov stations of air-showers registered simultaneously by the fluorescence and the surface detectors of the Pierre Auger Observatory. Such a correlation measurement is a unique feature of a hybrid air-shower observatory with sensitivity to both the electromagnetic and muonic components. It allows an accurate determination of the spread of primary masses in the cosmic-ray flux. Up till now, constraints on the spread of primary masses have been dominated by systematic uncertainties. The present correlation measurement is not affected by systematics in the measurement of the depth of shower maximum or the signal in the water Cherenkov stations. The analysis relies on general characteristics of air showers and is thus robust also with respect to uncertainties in hadronic event generators. The observed correlation in the energy range around the ‘ankle’ at lg(E/eV)=18.5–19.0lg(E/eV)=18.5–19.0 differs significantly from expectations for pure primary cosmic-ray compositions. A light composition made up of proton and helium only is equally inconsistent with observations. The data are explained well by a mixed composition including nuclei with mass A>4A>4. Scenarios such as the proton dip model, with almost pure compositions, are thus disfavored as the sole explanation of the ultrahigh-energy cosmic-ray flux at Earth
Erratum: Search for photons with energies above 1018 eV using the hybrid detector of the Pierre Auger Observatory (Journal of Cosmology and Astroparticle Physics (2017) 4 (9) DOI: 10.1088/1475-7516/2017/04/009)
No full text1 Exposure calculation Due to a mistake in the numerical integration following eq. (6.2) of the original article [1], the exposure shown in figure 5 of the original article was incorrect. The correct exposure is shown in figure 1. 2 Upper limits on the integral photon flux and fraction The incorrect exposure affects the calculation of the upper limits on the integral photon flux following eq. (6.1) of the original article. The correct values for the upper limits are 0.038, 0.010, 0.009, 0.008 and 0.007 km−2 sr−1 yr−1 for threshold energies of 1, 2, 3, 5 and 10 EeV. The correct values for the upper limits on the integral photon fraction subsequently derived are 0.14 %, 0.17 %, 0.42 %, 0.86 % and 2.9 % for the same threshold energies. 3 Author list The author list of this erratum also corrects a mistake made in the original article, where F. Zuccarello was missing and Z. Zong was listed twice
Self-correcting Bayesian target tracking
No full textThe copyright of this thesis rests with the author and no quotation from it or information derived from it may be published without the prior written consent of the authorAbstract
Visual tracking, a building block for many applications, has challenges such as occlusions,illumination changes, background clutter and variable motion dynamics that may degrade the
tracking performance and are likely to cause failures. In this thesis, we propose Track-Evaluate-Correct framework (self-correlation) for existing trackers in order to achieve a robust tracking.
For a tracker in the framework, we embed an evaluation block to check the status of tracking quality and a correction block to avoid upcoming failures or to recover from failures. We present a generic representation and formulation of the self-correcting tracking for Bayesian trackers using a Dynamic Bayesian Network (DBN). The self-correcting tracking is done similarly to a selfaware
system where parameters are tuned in the model or different models are fused or selected in a piece-wise way in order to deal with tracking challenges and failures. In the DBN model
representation, the parameter tuning, fusion and model selection are done based on evaluation and correction variables that correspond to the evaluation and correction, respectively. The inferences
of variables in the DBN model are used to explain the operation of self-correcting tracking. The specific contributions under the generic self-correcting framework are correlation-based selfcorrecting
tracking for an extended object with model points and tracker-level fusion as described below.
For improving the probabilistic tracking of extended object with a set of model points, we use Track-Evaluate-Correct framework in order to achieve self-correcting tracking. The framework
combines the tracker with an on-line performance measure and a correction technique. We correlate model point trajectories to improve on-line the accuracy of a failed or an uncertain tracker. A model point tracker gets assistance from neighbouring trackers whenever degradation in its
performance is detected using the on-line performance measure. The correction of the model point state is based on the correlation information from the states of other trackers. Partial Least
Square regression is used to model the correlation of point tracker states from short windowed trajectories adaptively. Experimental results on data obtained from optical motion capture systems show the improvement in tracking performance of the proposed framework compared to the
baseline tracker and other state-of-the-art trackers. The proposed framework allows appropriate re-initialisation of local trackers to recover from failures that are caused by clutter and missed
detections in the motion capture data.
Finally, we propose a tracker-level fusion framework to obtain self-correcting tracking. The
fusion framework combines trackers addressing different tracking challenges to improve the
overall performance. As a novelty of the proposed framework, we include an online performance measure to identify the track quality level of each tracker to guide the fusion. The trackers
in the framework assist each other based on appropriate mixing of the prior states. Moreover, the track quality level is used to update the target appearance model. We demonstrate the framework
with two Bayesian trackers on video sequences with various challenges and show its robustness
compared to the independent use of the trackers used in the framework, and also compared to
other state-of-the-art trackers. The appropriate online performance measure based appearance
model update and prior mixing on trackers allows the proposed framework to deal with tracking
challenges
Author Correction: A MHz-repetition-rate hard X-ray free-electron laser driven by a superconducting linear accelerator
No full textData-driven estimation of the invisible energy of cosmic ray showers with the Pierre Auger Observatory
No full textInternational audienceThe determination of the primary energy of extensive air showers using the fluorescence detection technique requires an estimation of the energy carried away by particles that do not deposit all their energy in the atmosphere. This estimation is typically made using Monte Carlo simulations and thus depends on the assumed primary particle mass and on model predictions for neutrino and muon production. In this work we present a new method to obtain the invisible energy from events detected by the Pierre Auger Observatory. The method uses measurements of the muon number at ground level, and it allows us to significantly reduce the systematic uncertainties related to the mass composition and the high energy hadronic interaction models, and consequently to improve the estimation of the energy scale of the Pierre Auger Observatory
Measurement of the cosmic-ray energy spectrum above eV using the Pierre Auger Observatory
No full textInternational audienceWe report a measurement of the energy spectrum of cosmic rays for energies above 2.5×1018 eV based on 215,030 events recorded with zenith angles below 60°. A key feature of the work is that the estimates of the energies are independent of assumptions about the unknown hadronic physics or of the primary mass composition. The measurement is the most precise made hitherto with the accumulated exposure being so large that the measurements of the flux are dominated by systematic uncertainties except at energies above 5×1019 eV. The principal conclusions are(1) The flattening of the spectrum near 5×1018 eV, the so-called “ankle,” is confirmed.(2) The steepening of the spectrum at around 5×1019 eV is confirmed.(3) A new feature has been identified in the spectrum: in the region above the ankle the spectral index γ of the particle flux (∝E-γ) changes from 2.51±0.03 (stat)±0.05 (syst) to 3.05±0.05 (stat)±0.10 (syst) before changing sharply to 5.1±0.3 (stat)±0.1 (syst) above 5×1019 eV.(4) No evidence for any dependence of the spectrum on declination has been found other than a mild excess from the Southern Hemisphere that is consistent with the anisotropy observed above 8×1018 eV
Direct measurement of the muonic content of extensive air showers between and eV at the Pierre Auger Observatory
No full textInternational audienceThe 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 and 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 and . We find that, for the models to explain the data, an increase in the muon density of for EPOS-LHC, and of for QGSJetII-04, is respectively needed
A 3-Year Sample of Almost 1,600 Elves Recorded Above South America by the Pierre Auger Cosmic-Ray Observatory
No full textThe time and location of the 1,598
verified and reconstructed elves, used
for the analysis showcased in this
paper, are publicly available on the
website of the Pierre Auger
Observatory (https://www.auger.org/
index.php/science/data). We wish to
thank the World Wide Lightning
Location Network (http://wwlln.net),
a collaboration among over 50
universities and institutions, for
providing the lightning location data
used in this paper. We acknowledge
Robert Marshall for providing one of
the most advanced elve simulations to
the public, a key tool in understanding
the elves observed by the Pierre Auger
Observatory. The successful
installation, commissioning, and
operation of the Pierre Auger
Observatory would not have been
possible without the strong
commitment and effort from the
technical and administrative staff in
Malargüe.Elves are a class of transient luminous events, with a radial extent typically greater than
250 km, that occur in the lower ionosphere above strong electrical storms. We report the observation of
1,598 elves, from 2014 to 2016, recorded with unprecedented time resolution (100 ns) using the
fluorescence detector (FD) of the Pierre Auger Cosmic-Ray Observatory. The Auger Observatory is located
in the Mendoza province of Argentina with a viewing footprint for elve observations of 3 · 106 km2,
reaching areas above the Pacific and Atlantic Oceans, as well as the Córdoba region, which is known for
severe convective thunderstorms. Primarily designed for ultrahigh energy cosmic-ray observations, the
Auger FD turns out to be very sensitive to the ultraviolet emission in elves. The detector features modified
Schmidt optics with large apertures resulting in a field of view that spans the horizon, and year-round
operation on dark nights with low moonlight background, when the local weather is favorable. The
measured light profiles of 18% of the elve events have more than one peak, compatible with intracloud
activity. Within the 3-year sample, 72% of the elves correlate with the far-field radiation measurements of
the World Wide Lightning Location Network. The Auger Observatory plans to continue operations until at
least 2025, including elve observations and analysis. To the best of our knowledge, this observatory is the
only facility on Earth that measures elves with year-round operation and full horizon coverage.Argentina—Comisión Nacional de
Energía Atómica; Agencia Nacional de
Promoción Científica y Tecnológica
(ANPCyT); Consejo Nacional de
Investigaciones Científicas y Técnicas
(CONICET); Gobierno de la Provincia
de Mendoza; Municipalidad de
Malargüe; and NDM Holdings and
Valle Las Leñas, in gratitude for their
continuing cooperation over land
access; Australia—the Australian
Research Council; Brazil—Conselho
Nacional de Desenvolvimento
Científico e Tecnológico (CNPq);
Financiadora de Estudos e Projetos
(FINEP); Fundação de Amparo à
Pesquisa do Estado de Rio de Janeiro
(FAPERJ); São Paulo Research
Foundation (FAPESP) Grants
2010/07359-6 and 1999/05404-3;
Ministério da Ciência, Tecnologia,
Inovações e Comunicações
(MCTIC); Czech Republic—Grants
MSMT CRLTT18004,
LO1305, LM2015038, and
CZ.02.1.01/0.0/0.0/16_013/0001402;
France—Centre de Calcul
IN2P3/CNRS; Centre National de la
Recherche Scientifique (CNRS);
Conseil Régional Ile-de-France;
Département Physique Nucléaire et
Corpusculaire (PNC-IN2P3/CNRS);
Département Sciences de l'Univers
(SDU-INSU/CNRS); Institut Lagrange
de Paris (ILP) Grant LABEX
ANR-10-LABX-63 within the
Investissements d'Avenir Programme
Grant ANR-11-IDEX-0004-02;
Germany—Bundesministerium für
Bildung und Forschung (BMBF);
Deutsche Forschungsgemeinschaft
(DFG); Finanzministerium
Baden-Württemberg; Helmholtz
Alliance for Astroparticle Physics
(HAP); Helmholtz-Gemeinschaft. Deutscher Forschungszentren (HGF);
Ministerium für Innovation,
Wissenschaft und Forschung des
Landes Nordrhein-Westfalen;
Ministerium für Wissenschaft,
Forschung und Kunst des Landes
Baden-Württemberg; Italy—Istituto
Nazionale di Fisica Nucleare (INFN);
Istituto Nazionale di Astrofisica
(INAF); Ministero dell'Istruzione,
dell'Universitá e della Ricerca (MIUR);
CETEMPS Center of Excellence;
Ministero degli Affari Esteri (MAE);
México—Consejo Nacional de Ciencia
y Tecnología (CONACYT)167733;
Universidad Nacional Autónoma de
México (UNAM); PAPIIT
DGAPA-UNAM; The
Netherlands—Ministry of Education,
Culture and Science; Netherlands
Organisation for Scientific Research
(NWO); Dutch National
e-Infrastructure with the support of
SURF Cooperative; Poland—National
Centre for Research and Development,
Grant ERA-NET-ASPERA/02/11;
National Science Centre, Grants
2013/08/M/ST9/00322,
2016/23/B/ST9/01635, and
HARMONIA
5–2013/10/M/ST9/00062,
UMO-2016/22/M/ST9/00198;
Portugal—Portuguese national funds
and FEDER funds within Programa
Operacional Factores de
Competitividade through Fundação
para a Ciência e a Tecnologia
(COMPETE); Romania—Romanian
Ministry of Research and
InnovationCNCS/CCCDI-UESFISCDI,
projects PN-III-P1-1.2-PCCDI-2017-
0839/19PCCDI/2018,
PN-III-P2-2.1-PED-2016-1922,
PN-III-P2-2.1-PED-2016-1659, and
PN18090102 within PNCDI III;
Slovenia—Slovenian Research
Agency; Spain—Comunidad de
Madrid; Fondo Europeo de Desarrollo
Regional (FEDER) funds; Ministerio
de Economía y Competitividad; Xunta
de Galicia; European Community 7th
Framework Program Grant
FP7-PEOPLE-2012-IEF-328826;
USA—Department of Energy,
Contracts DE-AC02-07CH11359,
DE-FR02-04ER41300,
DE-FG02-99ER41107, and
DE-SC0011689; National Science
Foundation, Grant 0450696; The
Grainger Foundation; Marie
Curie-IRSES/EPLANET; European
Particle Physics Latin American
Network; European Union 7th
Framework Program, Grant
PIRSES-2009-GA-246806; and
UNESCO
A Search for Ultra-high-energy Neutrinos from TXS 0506+056 Using the Pierre Auger Observatory
No full textInternational audienceResults of a search for ultra-high-energy neutrinos with the Pierre Auger Observatory from the direction of the blazar TXS 0506+056 are presented. They were obtained as part of the follow-up that stemmed from the detection of high-energy neutrinos and gamma rays with IceCube, Fermi-LAT, MAGIC, and other detectors of electromagnetic radiation in several bands. The Pierre Auger Observatory is sensitive to neutrinos in the energy range from 100 PeV to 100 EeV and in the zenith-angle range from θ = 60° to θ = 95°, where the zenith angle is measured from the vertical direction. No neutrinos from the direction of TXS 0506+056 have been found. The results were analyzed in three periods: one of 6 months around the detection of IceCube-170922 A, coinciding with a flare period of TXS 0506+056, a second one of 110 days during which the IceCube collaboration found an excess of 13 neutrinos from a direction compatible with TXS 0506+056, and a third one from 2004 January 1 up to 2018 August 31, over which the Pierre Auger Observatory has been taking data. The sensitivity of the Observatory is addressed for different spectral indices by considering the fluxes that would induce a single expected event during the observation period. For indices compatible with those measured by the IceCube collaboration the expected number of neutrinos at the Observatory is well below one. Spectral indices as hard as 1.5 would have to apply in this energy range to expect a single event to have been detected
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