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‣ Atmospheric effects on extensive air showers observed with the surface detector of the Pierre Auger observatory

ABRAHAM, J.; ABREU, P.; AGLIETTA, M.; AGUIRRE, C.; AHN, E. J.; ALLARD, D.; ALLEKOTTE, I.; ALLEN, J.; ALLISON, P.; ALVAREZ-MUNIZ, J.; AMBROSIO, M.; ANCHORDOQUI, L.; ANDRINGA, S.; ANZALONE, A.; ARAMO, C.; ARGANDA, E.; ARGIRO, S.; ARISAKA, K.; ARNEODO, F.; A
Fonte: ELSEVIER SCIENCE BV; AMSTERDAM Publicador: ELSEVIER SCIENCE BV; AMSTERDAM
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
99.7401%
Atmospheric parameters, Such as pressure (P), temperature (T) and density (rho proportional to P/T), affect the development of extensive air showers initiated by energetic cosmic rays. We have Studied the impact of atmospheric variations on extensive air showers by means of the surface detector of the Pierre Auger Observatory. The rate of events shows a similar to 10% seasonal modulation and similar to 2% diurnal one. We find that the observed behaviour is explained by a model including the effects associated with the variations of P and rho. The former affects the longitudinal development of air showers while the latter influences the Moliere radius and hence the lateral distribution of the shower particles. The model is validated with full simulations of extensive air showers using atmospheric profiles measured at the site of the Pierre Auger Observatory. (C) 2009 Elsevier B.V. All rights reserved.; Comisión Nacional de Energía Atómica, Argentina; Fundacion Antorchas; Gobierno De La Provincia de Mendoza, Municipalidad de Malargue, Argentina; NDM Holdings; Valle Las Lenas, Argentina; Australian Research Council (ARC); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Financiadora de Estudos e Projetos (FINEP); Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Ministério da Ciência...

‣ A study of the effect of molecular and aerosol conditions in the atmosphere on air fluorescence measurements at the Pierre Auger Observatory

ABRAHAM, J.; ABREU, P.; AGLIETTA, M.; AGUIRRE, C.; AHN, E. J.; ALLARD, D.; ALLEKOTTE, I.; ALLEN, J.; ALVAREZ-MUNIZ, J.; AMBROSIO, M.; ANCHORDOQUI, L.; ANDRINGA, S.; ANZALONE, A.; ARAMO, C.; ARGANDA, E.; ARISAKA, K.; ARQUEROS, F.; ASCH, T.; ASOREY, H.; ASS
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
79.328447%
The air fluorescence detector of the Pierre Auger Observatory is designed to perforin calorimetric measurements of extensive air showers created by Cosmic rays of above 10(18) eV. To correct these measurements for the effects introduced by atmospheric fluctuations, the Observatory contains a group Of monitoring instruments to record atmospheric conditions across the detector site, ail area exceeding 3000 km(2). The atmospheric data are used extensively in the reconstruction of air showers, and are particularly important for the correct determination of shower energies and the depths of shower maxima. This paper contains a summary of the molecular and aerosol conditions measured at the Pierre Auger Observatory since the start of regular operations in 2004, and includes a discussion of the impact of these measurements oil air shower reconstructions. Between 10(18) and 10(20) eV, the systematic Uncertainties due to all atmospheric effects increase from 4% to 8% in measurements of shower energy, and 4 g cm(-2) to 8 g cm(-2) in measurements of the shower maximum. (C) 2010 Elsevier B.V. All rights reserved.; Comision Nacional de Energia Atomica, Argentina; Fundacion Antorchas; Gobierno De La Provincia de Mendoza, Municipalidad de Malargue...

‣ Detecção de chuveiros atmosféricos iniciados por hádrons massivos; Detection of extensive air showers initiated by massive hadrons

Carvalho Junior, Washington Rodrigues de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 06/08/2008 Português
Relevância na Pesquisa
79.122095%
Nesta tese investigamos uma possível componente de partículas previstas por modelos além do modelo padrão da física de partículas, como por exemplo o massive gluino LSP, nos raios cósmicos de altíssimas energias (UHECR). Nosso objetivo é determinar os sinais experimentais em telescópios de fluorescência devidos a hádrons exóticos massivos e neutros, genericamente denominados de UHECRons. Para simular chuveiros iniciados por essa classe de partículas, alteramos o pacote Aires de simulação de chuveiros atmosféricos e o modelo hadrônico Sibyll. Estes chuveiros foram utilizados como entrada em simulações de telescópios de fluorescência por nós desenvolvidas, obtendo-se assim as distribuições dos observáveis desses chuveiros exóticos. A partir da comparação entre as características de chuveiros iniciados uhecrons e prótons, desenvolvemos métodos para a separação de sinais entre esses dois tipos de partículas. Esses métodos podem ser utilizados em uma análise inicial, com o intuito de procurar por sinais de partículas exóticas nos dados reais de observatórios de UHECR.; In this thesis we investigate a possible component of particles predicted by models beyond the standard model of particle physics...

‣ Reconstrução de chuveiros atmosféricos extensos detectados pelo Observatório Pierre Auger utilizando métodos robustos; Reconstruction of extensive air showers seen by the Pierre Auger Observatory using robust methods

Carlos Jose Todero Peixoto
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 28/08/2008 Português
Relevância na Pesquisa
99.2398%
Desde os primeiros Raios Cósmicos de alta energia detectados por Pierre Auger na década de 30, toda a comunidade de Física de Radiação Cósmica procura técnicas matemáticas e métodos estatísticos mais adequados para analisar estes eventos. Estes processos de análise são imprescindíveis na estimativa da energia da partícula primária, bem como no cálculo do ângulo de chegada q . A estimativa desta energia e do ângulo q é o final de toda uma rede de trabalho e o começo de uma nova linha de pesquisa na busca pelas possíveis fontes que produziram tais eventos. Ao longo deste trabalho refizemos o princípio de reconstrução dos "chuveiros de Auger", os chamados "Chuveiros Atmosféricos Extensos" ( C.A.E.), utilizando um conceito relativamente novo de estatística, hoje denominada Estatística Robusta. O Método dos Mínimos Quadrados ou Least Square -LS, apresentado por Gauss e Legendre, possuía limitações que eles próprios já reconheciam e tentaram resolver, sem sucesso. Desde fins do século XVIII e come¸ co do século XIX, os métodos estritamente paramétricos, em especial o Método dos Mínimos Quadrados e a média aritmética, foram questionados quando utilizados para descrever distribuições pouco comportadas ou com grandes utuações. Algumas das principais questões estavam relacionadas a como tratar pontos muito distantes da distribuição principal (os chamados outliers) e como estes influenciavam a própria distribuição. A saída convencional mais utilizada foi a rejeição dos outliers e de pontos que apresentassem grandes desvios em relação a média. Porém...

‣ Atmospheric effects on extensive air showers observed with the surface detector of the Pierre Auger observatory

ABRAHAM, J.; ABREU, P.; AGLIETTA, M.; AGUIRRE, C.; AHN, E. J.; ALLARD, D.; ALLEKOTTE, I.; ALLEN, J.; ALLISON, P.; ALVAREZ-MUNIZ, J.; AMBROSIO, M.; ANCHORDOQUI, L.; ANDRINGA, S.; ANZALONE, A.; ARAMO, C.; ARGANDA, E.; ARGIRO, S.; ARISAKA, K.; ARNEODO, F.; A
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
99.7401%
Atmospheric parameters, Such as pressure (P), temperature (T) and density (rho proportional to P/T), affect the development of extensive air showers initiated by energetic cosmic rays. We have Studied the impact of atmospheric variations on extensive air showers by means of the surface detector of the Pierre Auger Observatory. The rate of events shows a similar to 10% seasonal modulation and similar to 2% diurnal one. We find that the observed behaviour is explained by a model including the effects associated with the variations of P and rho. The former affects the longitudinal development of air showers while the latter influences the Moliere radius and hence the lateral distribution of the shower particles. The model is validated with full simulations of extensive air showers using atmospheric profiles measured at the site of the Pierre Auger Observatory. (C) 2009 Elsevier B.V. All rights reserved.; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

‣ A study of the effect of molecular and aerosol conditions in the atmosphere on air fluorescence measurements at the Pierre Auger Observatory

ABRAHAM, J.; ABREU, P.; AGLIETTA, M.; AGUIRRE, C.; AHN, E. J.; ALLARD, D.; ALLEKOTTE, I.; ALLEN, J.; ALVAREZ-MUNIZ, J.; AMBROSIO, M.; ANCHORDOQUI, L.; ANDRINGA, S.; ANZALONE, A.; ARAMO, C.; ARGANDA, E.; ARISAKA, K.; ARQUEROS, F.; ASCH, T.; ASOREY, H.; ASS
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
79.1871%
The air fluorescence detector of the Pierre Auger Observatory is designed to perforin calorimetric measurements of extensive air showers created by Cosmic rays of above 10(18) eV. To correct these measurements for the effects introduced by atmospheric fluctuations, the Observatory contains a group Of monitoring instruments to record atmospheric conditions across the detector site, ail area exceeding 3000 km(2). The atmospheric data are used extensively in the reconstruction of air showers, and are particularly important for the correct determination of shower energies and the depths of shower maxima. This paper contains a summary of the molecular and aerosol conditions measured at the Pierre Auger Observatory since the start of regular operations in 2004, and includes a discussion of the impact of these measurements oil air shower reconstructions. Between 10(18) and 10(20) eV, the systematic Uncertainties due to all atmospheric effects increase from 4% to 8% in measurements of shower energy, and 4 g cm(-2) to 8 g cm(-2) in measurements of the shower maximum. (C) 2010 Elsevier B.V. All rights reserved.; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

‣ Measuring a Cherenkov ring in the radio emission from air showers at 110-190 MHz with LOFAR

Nelles, A.; Schellart, P.; Buitink, S.; Corstanje, A.; de Vries, K. D.; Enriquez, J. E.; Falcke, H.; Frieswijk, W.; Hörandel, J. R.; Scholten, O.; ter Veen, S.; Thoudam, S.; van den Akker, M.; Anderson, J.; Asgekar, A.; Bell, M. E.; Bentum, M. J.; Bernar
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
78.98901%
Measuring radio emission from air showers offers a novel way to determine properties of the primary cosmic rays such as their mass and energy. Theory predicts that relativistic time compression effects lead to a ring of amplified emission which starts to dominate the emission pattern for frequencies above ~100 MHz. In this article we present the first detailed measurements of this structure. Ring structures in the radio emission of air showers are measured with the LOFAR radio telescope in the frequency range of 110 - 190 MHz. These data are well described by CoREAS simulations. They clearly confirm the importance of including the index of refraction of air as a function of height. Furthermore, the presence of the Cherenkov ring offers the possibility for a geometrical measurement of the depth of shower maximum, which in turn depends on the mass of the primary particle.; We acknowledge financial support from the Netherlands Research School for Astronomy (NOVA), the Samenwerkingsverband Noord-Nederland (SNN), the Foundation for Fundamental Research on Matter (FOM) and the Netherlands Organization for Scientific Research (NWO), VENI Grant 639-041-130. We acknowledge funding from an Advanced Grant of the European Research Council under the European Union’s Seventh Framework Program (FP/2007-2013)/ERC Grant Agreement no. 227610.

‣ Atmospheric effects on extensive air showers observed with the surface detector of the Pierre Auger observatory

Barber, K.; Bellido Caceres, J.; Clay, R.; Dawson, B.; Holmes, V.; Sorokin, J.; Wahrlich, P.; Whelan, B.; Winnick, M.
Fonte: Elsevier Science BV Publicador: Elsevier Science BV
Tipo: Artigo de Revista Científica
Publicado em //2009 Português
Relevância na Pesquisa
99.7401%
Atmospheric parameters, such as pressure (P), temperature (T) and density (ρ∝P/T), affect the development of extensive air showers initiated by energetic cosmic rays. We have studied the impact of atmospheric variations on extensive air showers by means of the surface detector of the Pierre Auger Observatory. The rate of events shows a 10% seasonal modulation and 2% diurnal one. We find that the observed behaviour is explained by a model including the effects associated with the variations of P and ρ. The former affects the longitudinal development of air showers while the latter influences the Molière radius and hence the lateral distribution of the shower particles. The model is validated with full simulations of extensive air showers using atmospheric profiles measured at the site of the Pierre Auger Observatory.; http://www.sciencedirect.com/science/journal/09276505; The Pierre Auger Collaboration... K.B. Barber... J.A. Bellido... R.W. Clay... B.R. Dawson... V.C. Holmes... J. Sorokin... P. Wahrlich... B.J. Whelan... M.G. Winnick... et al.

‣ Atmospheric effects on extensive air showers observed with the Surface Detector of the Pierre Auger Observatory

The Pierre Auger Collaboration
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
69.56991%
Atmospheric parameters, such as pressure (P), temperature (T) and density, affect the development of extensive air showers initiated by energetic cosmic rays. We have studied the impact of atmospheric variations on extensive air showers by means of the surface detector of the Pierre Auger Observatory. The rate of events shows a ~10% seasonal modulation and ~2% diurnal one. We find that the observed behaviour is explained by a model including the effects associated with the variations of pressure and density. The former affects the longitudinal development of air showers while the latter influences the Moliere radius and hence the lateral distribution of the shower particles. The model is validated with full simulations of extensive air showers using atmospheric profiles measured at the site of the Pierre Auger Observatory.; Comment: 24 pages, 9 figures, accepted for publication in Astroparticle Physics

‣ Nitrogen fluorescence in air for observing extensive air showers

Keilhauer, B.; Bohacova, M.; Fraga, M.; Matthews, J.; Sakaki, N.; Tameda, Y.; Tsunesada, Y.; Ulrich, A.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
69.40265%
Extensive air showers initiate the fluorescence emissions from nitrogen molecules in air. The UV-light is emitted isotropically and can be used for observing the longitudinal development of extensive air showers in the atmosphere over tenth of kilometers. This measurement technique is well-established since it is exploited for many decades by several cosmic ray experiments. However, a fundamental aspect of the air shower analyses is the description of the fluorescence emission in dependence on varying atmospheric conditions. Different fluorescence yields affect directly the energy scaling of air shower reconstruction. In order to explore the various details of the nitrogen fluorescence emission in air, a few experimental groups have been performing dedicated measurements over the last decade. Most of the measurements are now finished. These experimental groups have been discussing their techniques and results in a series of Air Fluorescence Workshops commenced in 2002. At the 8$^{\rm{th}}$ Air Fluorescence Workshop 2011, it was suggested to develop a common way of describing the nitrogen fluorescence for application to air shower observations. Here, first analyses for a common treatment of the major dependences of the emission procedure are presented. Aspects like the contributions at different wavelengths...

‣ Longitudinal development of extensive air showers: hybrid code SENECA and full Monte Carlo

Ortiz, Jeferson A.; Tanco, Gustavo Medina; de Souza, V.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 15/11/2004 Português
Relevância na Pesquisa
69.433096%
New experiments, exploring the ultra-high energy tail of the cosmic ray spectrum with unprecedented detail, are exerting a severe pressure on extensive air hower modeling. Detailed fast codes are in need in order to extract and understand the richness of information now available. Some hybrid simulation codes have been proposed recently to this effect (e.g., the combination of the traditional Monte Carlo scheme and system of cascade equations or pre-simulated air showers). In this context, we explore the potential of SENECA, an efficient hybrid tridimensional simulation code, as a valid practical alternative to full Monte Carlo simulations of extensive air showers generated by ultra-high energy cosmic rays. We extensively compare hybrid method with the traditional, but time consuming, full Monte Carlo code CORSIKA which is the de facto standard in the field. The hybrid scheme of the SENECA code is based on the simulation of each particle with the traditional Monte Carlo method at two steps of the shower development: the first step predicts the large fluctuations in the very first particle interactions at high energies while the second step provides a well detailed lateral distribution simulation of the final stages of the air shower. Both Monte Carlo simulation steps are connected by a cascade equation system which reproduces correctly the hadronic and electromagnetic longitudinal profile. We study the influence of this approach on the main longitudinal characteristics of proton-induced air showers and compare the predictions of the well known CORSIKA code using the QGSJET hadronic interaction model.; Comment: 11 pages (LaTeX)...

‣ New Simple Method for Analysis of Extensive Air Showers

Kh., H. Hedayati; Anvari, A.; Bahmanabadi, M.; Ghomi, M. Khakian; Samimi, J.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
69.531543%
Cosmic rays have valuable information about universe surroundings us. Finding energy, mass and arrival direction of primary cosmic ray particle are the most important aspects of extensive air shower studies. In order to determine these parameters, arrival direction and core position of extensive air showers should be determined at first. In this article, a new method has been introduced that utilizes arrival time information of secondary particles of extensive air showers for finding their core location and correcting plane wave front approximation so that calculate the arrival direction of extensive air showers. This method does not need number sensitive detectors-detectors which are sensitive to the number of crossing particles- and consequently there is no need for lateral distribution models. This model has been developed by analysis of simulated events generated by CORSIKA package.; Comment: published, and superseded by arXiv:1103.0662

‣ Polarized radio emission from extensive air showers measured with LOFAR

Schellart, P.; Buitink, S.; Corstanje, A.; Enriquez, J. E.; Falcke, H.; Hörandel, J. R.; Krause, M.; Nelles, A.; Rachen, J. P.; Scholten, O.; ter Veen, S.; Thoudam, S.; Trinh, T. N. G.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
69.460347%
We present LOFAR measurements of radio emission from extensive air showers. We find that this emission is strongly polarized, with a median degree of polarization of nearly $99\%$, and that the angle between the polarization direction of the electric field and the Lorentz force acting on the particles, depends on the observer location in the shower plane. This can be understood as a superposition of the radially polarized charge-excess emission mechanism, first proposed by Askaryan and the geomagnetic emission mechanism proposed by Kahn and Lerche. We calculate the relative strengths of both contributions, as quantified by the charge-excess fraction, for $163$ individual air showers. We find that the measured charge-excess fraction is higher for air showers arriving from closer to the zenith. Furthermore, the measured charge-excess fraction also increases with increasing observer distance from the air shower symmetry axis. The measured values range from $(3.3\pm 1.0)\%$ for very inclined air showers at $25\, \mathrm{m}$ to $(20.3\pm 1.3)\%$ for almost vertical showers at $225\, \mathrm{m}$. Both dependencies are in qualitative agreement with theoretical predictions.; Comment: 22 pages, 14 figures, accepted for publication in JCAP

‣ TeV black hole fragmentation and detectability in extensive air showers

Ahn, Eun-Joo; Ave, Maximo; Cavaglia, Marco; Olinto, Angela V.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
69.391196%
In models with large extra dimensions, particle collisions with center-of-mass energy larger than the fundamental gravitational scale can generate nonperturbative gravitational objects. Since cosmic rays have been observed with energies above $10^{8}$ TeV, gravitational effects in the TeV energy range can, in principle, be observed by ultrahigh energy cosmic ray detectors. We consider the interaction of ultrahigh energy neutrinos in the atmosphere and compare extensive air showers from TeV black hole formation and fragmentation with standard model processes. Departures from the standard model predictions arise in the interaction cross sections and in the multiplicity of secondary particles. Large theoretical uncertainties in the black hole cross section weaken attempts to constrain TeV gravity based solely on differences between predicted and observed event rates. The large multiplicity of secondaries in black hole fragmentation enhances the detectability of TeV gravity effects. We simulate TeV black hole air showers using PYTHIA and AIRES, and find that black hole-induced air showers are quite distinct from standard model air showers. However, the limited amount of information registered by realistic detectors together with large air shower fluctuations limit in practice the ability to distinguish TeV gravity events from standard model events in a shower by shower case. We discuss possible strategies to optimize the detectability of black hole events and propose a few unique signatures that may allow future high statistics detectors to separate black hole from standard model events.; Comment: RevTeX 4...

‣ LORA: A scintillator array for LOFAR to measure extensive air showers

Thoudam, S.; Buitink, S.; Corstanje, A.; Enriquez, J. E.; Falcke, H.; Frieswijk, W.; Hörandel, J. R.; Horneffer, A.; Krause, M.; Nelles, A.; Schellart, P.; Scholten, O.; ter Veen, S.; Akker, M. van den
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 19/08/2014 Português
Relevância na Pesquisa
69.389453%
The measurement of the radio emission from extensive air showers, induced by high-energy cosmic rays is one of the key science projects of the LOFAR radio telescope. The LOfar Radboud air shower Array (LORA) has been installed in the core of LOFAR in the Netherlands. The main purpose of LORA is to measure the properties of air showers and to trigger the read-out of the LOFAR radio antennas to register extensive air showers. The experimental set-up of the array of scintillation detectors and its performance are described.; Comment: 10 pages, Accepted for publication in Nuclear Instruments and Methods A

‣ Radio-detection of extensive air showers at the Pierre Auger Observatory - Results and enhancements

Louedec, K.; Collaboration, for the Pierre Auger
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 17/10/2013 Português
Relevância na Pesquisa
69.51781%
The Pierre Auger Collaboration is exploring the potential of radio-detection techniques to measure the extensive air showers. The main advantage of these setups is the possibility to cover a large area with no atmospheric attenuation and having 100% duty cycle. Radio emission in the MHz range is recorded by the Auger Engineering Radio Array (AERA), presently consisting of 124 stations distributed over an area of approximately 6 km$^2$. This enhancement is focused on physics of cosmic rays with an energy greater than 10$^{17}$ eV. In addition, novel detection techniques based on the GHz emission from extensive air showers are being tested at the Pierre Auger Observatory. Three different setups are currently installed and are collecting data: MIDAS (Microwave Detection of Air Showers) and AMBER (Air-shower Microwave Bremsstrahlung Experimental Radiometer) are prototypes of an imaging parabolic dish detector, while EASIER (Extensive Air Shower Identification using Electron Radiometer) records the radio emission by antenna horns located on more than 60 surface detector units. The status of these different activities and the new results in MHz and GHz bands will be reported.; Comment: 3 pages -- EPS-HEP'13 European Physical Society Conference on High Energy Physics (July...

‣ The shape of the radio wavefront of extensive air showers as measured with LOFAR

Corstanje, A.; Schellart, P.; Nelles, A.; Buitink, S.; Enriquez, J. E.; Falcke, H.; Frieswijk, W.; Hörandel, J. R.; Krause, M.; Rachen, J. P.; Scholten, O.; ter Veen, S.; Thoudam, S.; Trinh, G.; Akker, M. van den; Alexov, A.; Anderson, J.; Avruch, I. M.;
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
69.389453%
Extensive air showers, induced by high energy cosmic rays impinging on the Earth's atmosphere, produce radio emission that is measured with the LOFAR radio telescope. As the emission comes from a finite distance of a few kilometers, the incident wavefront is non-planar. A spherical, conical or hyperbolic shape of the wavefront has been proposed, but measurements of individual air showers have been inconclusive so far. For a selected high-quality sample of 161 measured extensive air showers, we have reconstructed the wavefront by measuring pulse arrival times to sub-nanosecond precision in 200 to 350 individual antennas. For each measured air shower, we have fitted a conical, spherical, and hyperboloid shape to the arrival times. The fit quality and a likelihood analysis show that a hyperboloid is the best parametrization. Using a non-planar wavefront shape gives an improved angular resolution, when reconstructing the shower arrival direction. Furthermore, a dependence of the wavefront shape on the shower geometry can be seen. This suggests that it will be possible to use a wavefront shape analysis to get an additional handle on the atmospheric depth of the shower maximum, which is sensitive to the mass of the primary particle.; Comment: Accepted for publication in Astroparticle Physics

‣ High-precision measurements of extensive air showers with the SKA

Huege, T.; Bray, J. D.; Buitink, S.; Dallier, R.; Ekers, R. D.; Falcke, H.; Haungs, A.; James, C. W.; Martin, L.; Revenu, B.; Scholten, O.; Schröder, F. G.; Zilles, A.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 14/08/2015 Português
Relevância na Pesquisa
69.391196%
As of 2023, the Square Kilometre Array will constitute the world's largest radio telescope, offering unprecedented capabilities for a diverse science programme in radio astronomy. At the same time, the SKA will be ideally suited to detect extensive air showers initiated by cosmic rays in the Earth's atmosphere via their radio emission. With its very dense and uniform antenna spacing in a fiducial area of one km$^2$ and its large bandwidth of 50-350 MHz, the low-frequency part of the SKA will provide very precise measurements of individual cosmic ray air showers. These precision measurements will allow detailed studies of the mass composition of cosmic rays in the energy region of transition from a Galactic to an extragalactic origin. Also, the SKA will facilitate three-dimensional "tomography" of the electromagnetic cascades of air showers, allowing the study of particle interactions at energies beyond the reach of the LHC. Finally, studies of possible connections between air showers and lightning initiation can be taken to a new level with the SKA. We discuss the science potential of air shower detection with the SKA and report on the technical requirements and project status.; Comment: Proceedings of the 34th ICRC, The Hague, The Netherlands...

‣ Altitude dependence of fluorescence light emission by extensive air showers

Keilhauer, B.; Bluemer, J.; Engel, R.; Klages, H. O.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
69.389453%
Fluorescence light is induced by extensive air showers while developing in the Earth's atmosphere. The number of emitted fluorescence photons depends on the conditions of the air and on the energy deposited by the shower particles at every stage of the development. In a previous model calculation, the pressure and temperature dependences of the fluorescence yield have been studied on the basis of kinetic gas theory, assuming temperature-independent molecular collision cross-sections. In this work we investigate the importance of temperature-dependent collision cross-sections and of water vapour quenching on the expected fluorescence yield. The calculations will be applied to simulated air showers while using actual atmospheric profiles to estimate the influence on the reconstructed energy of extensive air showers.; Comment: 8 pages, 18 figures, to be published in Proc. 5th Fluorescence Workshop, El Escorial - Madrid, Sept. 2007

‣ Atmospheric effects on extensive air showers observed with the surface detector of the Pierre Auger observatory

Abraham, J.; Abreu, P.; Aglietta, M.; Aguirre, C.; Ahn, E. J.; Allard, D.; Allekotte, I.; Allen, J.; Allison, P.; Alvarez-Muñiz, J.; Ambrosio, M.; Anchordoqui, L.; Andringa, S.; Anzalone, A.; Aramo, C.; Arganda, E.; Argirò, S.; Arisaka, K.; Arneodo, F.;
Fonte: Elsevier Publicador: Elsevier
Tipo: Article; PeerReviewed Formato: application/pdf
Publicado em /09/2009 Português
Relevância na Pesquisa
69.56991%
Atmospheric parameters, such as pressure (P), temperature (T) and density (ρ∝P/T), affect the development of extensive air showers initiated by energetic cosmic rays. We have studied the impact of atmospheric variations on extensive air showers by means of the surface detector of the Pierre Auger Observatory. The rate of events shows a not, vert, similar 10% seasonal modulation and not, vert, similar 2% diurnal one. We find that the observed behaviour is explained by a model including the effects associated with the variations of P and ρ. The former affects the longitudinal development of air showers while the latter influences the Molière radius and hence the lateral distribution of the shower particles. The model is validated with full simulations of extensive air showers using atmospheric profiles measured at the site of the Pierre Auger Observatory.