Codalema is one of the experiments devoted to the detection of ultra high energy cosmic rays by the radio method. The main objective is to study the features of the radio signal induced by the development in the atmosphere of extensive air showers (EAS) generated by cosmic rays in the energy range of 10 PeV-1 EeV . After a brief presentation of the detector features, the main results obtained are reported (emission mechanism, lateral distribution of the electric field, energy calibration, etc.). The first studies of the radio wave front curvature are discussed as new preliminary results.
Some possible interpretations from data of the CODALEMA experimentAhmed Ammar Rebai PhD
The purpose of the CODALEMA experiment, installed at the Nan\c{c}ay Radio Observatory (France), is to study the radio-detection of ultra-high energy cosmic rays in the energy range of 10^{16}-10^{18} eV. Distributed over an area of 0.25 km^2, the original device uses in coincidence an array of particle detectors and an array of short antennas, with a centralized acquisition. A new analysis of the observable in energy for radio is presented from this system, taking into account the geomagnetic effect. Since 2011, a new array of radio-detectors, consisting of 60 stand-alone and self-triggered stations, is being deployed over an area of 1.5 km^2 around the initial configuration. This new development leads to specific constraints to be discussed in term of recognition of cosmic rays and in term of analysis of wave-front.
Why radiodetection of UHECR still matters ? Karlsruhe Institute of Technol...Ahmed Ammar Rebai PhD
In the field of radiodetection in astroparticle physics, the Codalema experiment is devoted to the detection of ultra high energy cosmic rays by the radio method. The main objective is to study the features of the radio signal induced by the development of extensive air showers (EAS) generated by cosmic rays in the energy range of 10 PeV-1 EeV. After a brief presentation of the recent results of UHECR, a description the CODALEMA II and III experiments characteristics is reported.
Next, a study of the response in energy of the radio-detection method is presented. The analysis of the CODALEMA II experiment data shows that a strong correlation can be demonstrated between the primary energy and the electric field amplitude on the axis shower. Its sensitivity to the shower characteristics suggests that energy resolution of less than 20% can be achieved. It suggests also that, not only the geomagnetic emission, but also another contribution proportional to all charged particles number in the shower, could play a significant role in the radio emission measured by the antennas (as Askaryan charge-excess radiation or a Cherenkov like coherence effect).
Finally, the transition from small-scale prototype experiments, triggered by particle detectors, to large-scale antenna array experiments based on standalone detection, has emerged new problems. These problems are related to the localization, recognition and the suppression of the noisy background sources induced by human activities (such as high voltage power lines, electric transformers, cars, trains and planes) or by stormy weather conditions (such as lightning). In this talk, we focus on the localization problem which belongs to a class of more general problems usually termed as inverse problems. Many studies have shown the strong dependence of the solution of the radio-transient sources localization problem (the radio wavefront time of arrival on antennas TOA), such solutions are purely numerical artifacts. Based on a detailed analysis of some already published results of radio-detection experiments like : CODALEMA 3 in France, AERA in Argentina, TREND in China and LUNASKA in Australia, we demonstrate the ill-posed character of this problem in the sense of Hadamard. Two approaches have been used as the existence of solutions degeneration and the bad conditioning of the mathematical formulation of the problem. A comparison between the experimental results and the simulations have been made, to support the mathematical studies. Many properties of the non-linear least square function are discussed such as the configuration of the set of solutions and the bias.
The shape radio_signals_wavefront_encountered_in_the_context_of_the_uhecr_rad...Ahmed Ammar Rebai PhD
"Uploaded only for Authors copyrights 9/9/2014. All rights reserved"
Ultra high energy cosmic rays are the most extreme energetic subatomic particles
in nature. Coming from the outer space, these particles initiate extensive air showers (EAS) in
the Earth’s atmosphere. The generated EAS produce elusive radio-transients in the MHz frequency
band measured by sensitive antenna arrays and radio telescopes. Theoretical developments indicate
that the EAS radio wavefront shape depends on the shower longitudinal development, it is waited
that the wavefront curved shape provides information to answer many fundamental questions about
UHECR nature and origins. In the first part of this paper, we report on an investigation in the
wavefront shape, based on an already published sample of events collected between November
2006 and January 2010 at the CODALEMA II experiment located in the radioastronomy facility at
Nançay in France. We find that measurements of individual air showers have been conclusive for
a non-planar shape which could be hyperbolical (further analysis are needed). By cons and in the
second part of this paper, a spherical shape of the wavefront for the anthropic radio-sources has been
proposed. Many studies have shown the strong dependence of the solution of the radio-transient
sources localization problem (the radio wavefront time of arrival on antennas TOA), such solutions
are purely numerical artifacts. Based on a detailed analysis of some published results of radio-
detection experiments around the world like : CODALEMA III in France, AERA in Argentina,
TREND in China and LUNASKA in Australia, we demonstrate the ill-posed character of this
problem in the sense of Hadamard. To support the mathematical studies, a comparison between the
experimental results and the simulations have been made.
24 Polarization observable measurements for γp → K+Λ and γp → K+Σ for energie...Cristian Randieri PhD
Polarization observable measurements for γp → K+Λ and γp → K+Σ for energies up to 1.5 GeV - The European Physical Journal A, Hadrons and Nuclei, January 2007, Vol. 31, N. 1, pp. 73-93, ISSN: 1434-6001, doi: 10.1140/epja/i2006-10167-8
di A. Lleres, O. Bartalini, V. Bellini, J. P. Bocquet, P. Calvat, M. Capogni, L. Casano, M. Castoldi, A. D'Angelo, J. P. Didelez, R. Di Salvo, A. Fantini, C. Gaulard, G. Gervino, F. Ghio, B. Girolami, A. Giusa, M. Guidal, E. Hourany, V. Kouznetsov, R. Kunne, A. Lapik, P. Levi Sandri, D. Moricciani, A. N. Mushkarenkov, V. Nedorezov, L. Nicoletti, C. Perrin, C. Randieri, D. Rebreyend, F. Renard, N. Rudnev, T. Russew, G. Russo, C. Schaerf, M. L. Sperduto, M. C. Sutera, A. Turinge (2007)
Abstract
Beam asymmetries and hyperon recoil polarizations for the reactions γ p → K +Λ and γ p → K +Σ0 have been measured from the threshold production to 1500MeV with the GRAAL facility located at the ESRF in Grenoble. These results complement the database for the beam asymmetry, covering for the first time the production threshold region. Recent theoretical analyses are presented for which the beam asymmetry data bring interesting new information and allow to better determine some resonance parameters. Most importantly, these results strengthen the need of a new D13 state around 1900MeV.
Agu maosi chen h31g-1590 retrieval of surface ozone from uv-mfrsr irradiances...Maosi Chen
High concentration of surface ozone is harmful to humans and plants. USDA UV-B Monitoring and Research Program (UVMRP) uses Ultraviolet (UV) version of Multi-Filter Rotating Shadowband Radiom-eter (UV-MFRSR) to measure direct, diffuse, and total irradiances every 3 minutes at 7 UV channels (i.e. 300, 305, 311, 317, 325, 332, and 368 nm channels with 2 nm full width at half maximum). There have been plenty of literature exploring retrieval methods of total column ozone from UV-MFRSR measurements, but few has explored the retrieval of surface ozone. Under clear-sky conditions, UV irradiances absorption by ozone are significant and variable by height and wavelength. Therefore, multi-channel UV irradiances at the ground have the potential to resolve ozone concentrations at multiple vertical layers (including surface ozone). In this study, we used a deep learning algorithm (i.e. Self-Normalizing Neural Network, SNN) to retrieve surface ozone from 3-minute UV-MFRSR direct and diffuse irradiances (and the airmass) under clear-sky conditions at the UVMRP station located at Billings, Oklahoma. The 3-minute surface ozone data for training and validation are accumulated from 1-second surface ozone measured at the collocated Southern Great Plains (SGP) station by US Department of Energy Atmospheric Radiation Measurement Climate Research Facility (ARM). To cover the cloudy conditions, we also explored several spatial interpolation techniques [i.e. Triangulation-based linear interpolation, Graph Convolutional Neural Network (GCNN or ChebNet), mixture model network (MoNet), and Re-current Neural Network (RNN)] to estimate the hourly surface ozone at the same UVMRP station from the adjacent (i.e. within the 3-degree box of) US Environmental Protection Agency (EPA) hourly surface ozone observations.
Study of the solar radiation in Ecuador and its effects on the behavior of ph...Javier García Molleja
English version of the MSc final work held at Universitat de Barcelona - Centro Universitario Internacional de Barcelona (2017, Spain). MSc in Renewable Energy and Energetic Sustainability.
Tutor: Bernat Codina
Co-tutor: Graciela Salum
Jury: Camila Barreneche, Alejandro Calderón
Some possible interpretations from data of the CODALEMA experimentAhmed Ammar Rebai PhD
The purpose of the CODALEMA experiment, installed at the Nan\c{c}ay Radio Observatory (France), is to study the radio-detection of ultra-high energy cosmic rays in the energy range of 10^{16}-10^{18} eV. Distributed over an area of 0.25 km^2, the original device uses in coincidence an array of particle detectors and an array of short antennas, with a centralized acquisition. A new analysis of the observable in energy for radio is presented from this system, taking into account the geomagnetic effect. Since 2011, a new array of radio-detectors, consisting of 60 stand-alone and self-triggered stations, is being deployed over an area of 1.5 km^2 around the initial configuration. This new development leads to specific constraints to be discussed in term of recognition of cosmic rays and in term of analysis of wave-front.
Why radiodetection of UHECR still matters ? Karlsruhe Institute of Technol...Ahmed Ammar Rebai PhD
In the field of radiodetection in astroparticle physics, the Codalema experiment is devoted to the detection of ultra high energy cosmic rays by the radio method. The main objective is to study the features of the radio signal induced by the development of extensive air showers (EAS) generated by cosmic rays in the energy range of 10 PeV-1 EeV. After a brief presentation of the recent results of UHECR, a description the CODALEMA II and III experiments characteristics is reported.
Next, a study of the response in energy of the radio-detection method is presented. The analysis of the CODALEMA II experiment data shows that a strong correlation can be demonstrated between the primary energy and the electric field amplitude on the axis shower. Its sensitivity to the shower characteristics suggests that energy resolution of less than 20% can be achieved. It suggests also that, not only the geomagnetic emission, but also another contribution proportional to all charged particles number in the shower, could play a significant role in the radio emission measured by the antennas (as Askaryan charge-excess radiation or a Cherenkov like coherence effect).
Finally, the transition from small-scale prototype experiments, triggered by particle detectors, to large-scale antenna array experiments based on standalone detection, has emerged new problems. These problems are related to the localization, recognition and the suppression of the noisy background sources induced by human activities (such as high voltage power lines, electric transformers, cars, trains and planes) or by stormy weather conditions (such as lightning). In this talk, we focus on the localization problem which belongs to a class of more general problems usually termed as inverse problems. Many studies have shown the strong dependence of the solution of the radio-transient sources localization problem (the radio wavefront time of arrival on antennas TOA), such solutions are purely numerical artifacts. Based on a detailed analysis of some already published results of radio-detection experiments like : CODALEMA 3 in France, AERA in Argentina, TREND in China and LUNASKA in Australia, we demonstrate the ill-posed character of this problem in the sense of Hadamard. Two approaches have been used as the existence of solutions degeneration and the bad conditioning of the mathematical formulation of the problem. A comparison between the experimental results and the simulations have been made, to support the mathematical studies. Many properties of the non-linear least square function are discussed such as the configuration of the set of solutions and the bias.
The shape radio_signals_wavefront_encountered_in_the_context_of_the_uhecr_rad...Ahmed Ammar Rebai PhD
"Uploaded only for Authors copyrights 9/9/2014. All rights reserved"
Ultra high energy cosmic rays are the most extreme energetic subatomic particles
in nature. Coming from the outer space, these particles initiate extensive air showers (EAS) in
the Earth’s atmosphere. The generated EAS produce elusive radio-transients in the MHz frequency
band measured by sensitive antenna arrays and radio telescopes. Theoretical developments indicate
that the EAS radio wavefront shape depends on the shower longitudinal development, it is waited
that the wavefront curved shape provides information to answer many fundamental questions about
UHECR nature and origins. In the first part of this paper, we report on an investigation in the
wavefront shape, based on an already published sample of events collected between November
2006 and January 2010 at the CODALEMA II experiment located in the radioastronomy facility at
Nançay in France. We find that measurements of individual air showers have been conclusive for
a non-planar shape which could be hyperbolical (further analysis are needed). By cons and in the
second part of this paper, a spherical shape of the wavefront for the anthropic radio-sources has been
proposed. Many studies have shown the strong dependence of the solution of the radio-transient
sources localization problem (the radio wavefront time of arrival on antennas TOA), such solutions
are purely numerical artifacts. Based on a detailed analysis of some published results of radio-
detection experiments around the world like : CODALEMA III in France, AERA in Argentina,
TREND in China and LUNASKA in Australia, we demonstrate the ill-posed character of this
problem in the sense of Hadamard. To support the mathematical studies, a comparison between the
experimental results and the simulations have been made.
24 Polarization observable measurements for γp → K+Λ and γp → K+Σ for energie...Cristian Randieri PhD
Polarization observable measurements for γp → K+Λ and γp → K+Σ for energies up to 1.5 GeV - The European Physical Journal A, Hadrons and Nuclei, January 2007, Vol. 31, N. 1, pp. 73-93, ISSN: 1434-6001, doi: 10.1140/epja/i2006-10167-8
di A. Lleres, O. Bartalini, V. Bellini, J. P. Bocquet, P. Calvat, M. Capogni, L. Casano, M. Castoldi, A. D'Angelo, J. P. Didelez, R. Di Salvo, A. Fantini, C. Gaulard, G. Gervino, F. Ghio, B. Girolami, A. Giusa, M. Guidal, E. Hourany, V. Kouznetsov, R. Kunne, A. Lapik, P. Levi Sandri, D. Moricciani, A. N. Mushkarenkov, V. Nedorezov, L. Nicoletti, C. Perrin, C. Randieri, D. Rebreyend, F. Renard, N. Rudnev, T. Russew, G. Russo, C. Schaerf, M. L. Sperduto, M. C. Sutera, A. Turinge (2007)
Abstract
Beam asymmetries and hyperon recoil polarizations for the reactions γ p → K +Λ and γ p → K +Σ0 have been measured from the threshold production to 1500MeV with the GRAAL facility located at the ESRF in Grenoble. These results complement the database for the beam asymmetry, covering for the first time the production threshold region. Recent theoretical analyses are presented for which the beam asymmetry data bring interesting new information and allow to better determine some resonance parameters. Most importantly, these results strengthen the need of a new D13 state around 1900MeV.
Agu maosi chen h31g-1590 retrieval of surface ozone from uv-mfrsr irradiances...Maosi Chen
High concentration of surface ozone is harmful to humans and plants. USDA UV-B Monitoring and Research Program (UVMRP) uses Ultraviolet (UV) version of Multi-Filter Rotating Shadowband Radiom-eter (UV-MFRSR) to measure direct, diffuse, and total irradiances every 3 minutes at 7 UV channels (i.e. 300, 305, 311, 317, 325, 332, and 368 nm channels with 2 nm full width at half maximum). There have been plenty of literature exploring retrieval methods of total column ozone from UV-MFRSR measurements, but few has explored the retrieval of surface ozone. Under clear-sky conditions, UV irradiances absorption by ozone are significant and variable by height and wavelength. Therefore, multi-channel UV irradiances at the ground have the potential to resolve ozone concentrations at multiple vertical layers (including surface ozone). In this study, we used a deep learning algorithm (i.e. Self-Normalizing Neural Network, SNN) to retrieve surface ozone from 3-minute UV-MFRSR direct and diffuse irradiances (and the airmass) under clear-sky conditions at the UVMRP station located at Billings, Oklahoma. The 3-minute surface ozone data for training and validation are accumulated from 1-second surface ozone measured at the collocated Southern Great Plains (SGP) station by US Department of Energy Atmospheric Radiation Measurement Climate Research Facility (ARM). To cover the cloudy conditions, we also explored several spatial interpolation techniques [i.e. Triangulation-based linear interpolation, Graph Convolutional Neural Network (GCNN or ChebNet), mixture model network (MoNet), and Re-current Neural Network (RNN)] to estimate the hourly surface ozone at the same UVMRP station from the adjacent (i.e. within the 3-degree box of) US Environmental Protection Agency (EPA) hourly surface ozone observations.
Study of the solar radiation in Ecuador and its effects on the behavior of ph...Javier García Molleja
English version of the MSc final work held at Universitat de Barcelona - Centro Universitario Internacional de Barcelona (2017, Spain). MSc in Renewable Energy and Energetic Sustainability.
Tutor: Bernat Codina
Co-tutor: Graciela Salum
Jury: Camila Barreneche, Alejandro Calderón
Natural radiation levels and health hazard indices of soil in Owerri Nigeriatheijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
Theoretical work submitted to the Journal should be original in its motivation or modeling structure. Empirical analysis should be based on a theoretical framework and should be capable of replication. It is expected that all materials required for replication (including computer programs and data sets) should be available upon request to the authors.
The International Journal of Engineering & Science would take much care in making your article published without much delay with your kind cooperation
Data analysis of THE MOST IMPORTANT CHARTS IN THE ECONOMY TODAYAhmed Ammar Rebai PhD
I am Ahmed REBAI, I just get my PhD diploma in nuclear physics in December 2013. Through this presentation inspired from an article of Matthew Boesler (Business Insider journal) I would like to show the data analysis methods applied in Finance and Economy.
Natural radiation levels and health hazard indices of soil in Owerri Nigeriatheijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
Theoretical work submitted to the Journal should be original in its motivation or modeling structure. Empirical analysis should be based on a theoretical framework and should be capable of replication. It is expected that all materials required for replication (including computer programs and data sets) should be available upon request to the authors.
The International Journal of Engineering & Science would take much care in making your article published without much delay with your kind cooperation
Data analysis of THE MOST IMPORTANT CHARTS IN THE ECONOMY TODAYAhmed Ammar Rebai PhD
I am Ahmed REBAI, I just get my PhD diploma in nuclear physics in December 2013. Through this presentation inspired from an article of Matthew Boesler (Business Insider journal) I would like to show the data analysis methods applied in Finance and Economy.
Fiche méthodes sur les nombres complexes Prépas MPSI PCSI PTSI BCPST2Ahmed Ammar Rebai PhD
Le document quelques méthodes sur les nombres complexes selon le programme des classes préparatoires aux grandes écoles d'ingénieurs en France: MPSI, PCSI, PTSI et aussi BCPST2
Le fichier contient l'énoncé de l'épreuve de mathématiques I de l'ESSEC 2015 avec une correction incomplète pour l'instant mais je vais continuer à mettre les réponses de questions au fur et à mesure....
Epreuve mathématiques II ESSEC 2015 ECE + Correction des partie II et IIIAhmed Ammar Rebai PhD
Le fichier contient l'énoncé de l'épreuve de mathématiques II de l'ESSEC 2015 avec une correction des parties II et III. En théorie des probabilités, la queue d'une loi de probabilité est le comportement de cette loi dans la zone éloignée de sa valeur centrale (on parle aussi de la traîne ou "the tail"). On distingue entre les distributions ayant une queue légère ou lourde. Cette notion trouve son application dans plusieurs domaine:
- En hydrologie: pour prédire les crues du Nil, de la Loire...
- En finance: pour décrire l'évolution d'un stock avec entrées et sorties
- En assurance: assurance non-vie
- En théorie de risque: risques en santé ( risque alimentaire)
- En informatique: files d'attente de requêtes demandées à un serveur.
Evidence for the charge-excess contribution in air shower radio emission obse...Ahmed Ammar Rebai PhD
The following paper I co-authored is now online on slideshare! I participated in the Codalema Experiment operations and data analysis since July 2009 until February 2014.
Context. Observation of the charge-excess mechanism in the emission of the electric field from cosmic ray air showers.
Aims. It is shown that the signature of the charge-excess mechanism is present in the CODALEMA data
Methods. The data exhibits a shift in the ground position in the shower cores seen from the radio data and the particle
data. This shift is explained when using a simulation code taking into account or not the charge-excess mechanism.
Results. Evidence for the charge-excess in the atmospheric shower has been found via the electric field emitted by the
secondary particle and detected by the CODALEMA experiment.
Conclusions. The systematic shift between the shower core estimation using separately the particle array data and
the radio array data of the CODALEMA experiment is discussed. Using the simulation code SELFAS2 we show that
the consideration of the charge-excess contribution in the total radio emission of air showers generates a shift of the
apparent ground radio core along the east-west axis in good agreement with the observations. This radio core shift is
then characterized for the CODALEMA setup and compared with the data. The observation of this systematic shift
can be considered as an experimental signature of the charge excess contribution.
Towards the identification of the primary particle nature by the radiodetecti...Ahmed Ammar Rebai PhD
To contact the author use ahmed.rebai2@gmail.com
Radio signal from extensive air showers EAS studied by the CODALEMA experiment have been detected by means of the classic short fat antennas array working in a slave trigger mode by a particle scintillator array. It is shown that the radio shower wavefront is curved with respect to the plane wavefront hypothesis. Then a new fitting model (parabolic model) is proposed to fit the radio signal time delay distributions in an event-by-event basis. This model take into account this wavefront property and several shower geometry parameters such as: the existence of an apparent localised radio-emission source located at a distance Rc from the antenna array of and the
radio shower core on the ground. Comparison of the outputs from this model and other reconstruction models used in the same experiment show: 1)- That the radio shower core is shifted from the particle shower core in a statistic analysis approach. 2)- The capability of the radiodetection method to reconstruct the curvature radius
with a statistical error less than 50 g.cm−2 . Finally a preliminary study of the primary particle nature has been performed based on a comparison between data and Xmax distribution from Aires Monte-Carlo simulations for the same set of events.
Towards the identification of the primary particle nature by the radiodetecti...Ahmed Ammar Rebai PhD
Radio signal from extensive air showers EAS studied by the CODALEMA experiment have been detected by means of the classic short fat antennas array working in a slave trigger mode by a particle scintillator array. It is shown that the radio shower wavefront is curved with respect to the plane wavefront hypothesis. Then a new tting model (parabolic model) is proposed to fit the radio signal time delay distributions in an event-by-event basis. This model take
into account this wavefront property and several shower geometry parameters such as: the existence of an apparent localised radio-emission source located at a distance Rc from the antenna array of and the radio shower core on the
ground. Comparison of the outputs from this model and other reconstruction models used in the same experiment show:
1)- That the radio shower core is shifted from the particle shower core in a statistic analysis approach.
2)- The capability of the radiodetection method to reconstruct the curvature radius with a statistical error less than 50 g.cm−2 .
Finally a preliminary study of the primary particle nature has been performed based on a comparison between data and Xmax distribution from Aires Monte-Carlo simulations for the same set of events.
This is the presentation I gave when defending my Ph.D thesis at SLAC. The title of my defense was "Neutron Star Powered Nebulae: a New View on Pulsar Wind Nebulae with the Fermi Gamma-ray Space Telescope".
Numerical studies of the radiation patterns of resistively loaded dipolesLeonid Krinitsky
The far field radiation patterns of finite-size resistively loaded horizontal electric dipoles lying on a low-loss dielectric half-space are computed. The patterns are a superposition of the solutions for transient infinitesimal dipole elements, where the transient waveform for each element is synthesized from the exact steady-state solution. The current excitation for each dipole element is a half cycle of a sine squared waveform that propagates along the line of elements at a speed that can be varied. No reflections from the antenna ends are assumed. The time duration of the current half cycle governs the full period of the dominant part of the transient radiated waveform. The amplitude of the dipole excitation current is determined by a cosine distribution that accurately simulates the resistive loading. The transient radiation patterns differ from those of a steady-state dipole mainly by being more narrow in the E-plane, as is true for a finite-size steady-state dipole radiating in air. In addition, the far field waveforms are slightly distorted in directions off vertical in the E-plane. Two-way power radiation patterns are presented for both conductive and non-conductive dielectric media in a footprint mode, i.e. the power response to an isotropic point scatterer on a subsurface flat plane. The radar footprint in a conductive dielectric shows very narrow beamwidth due to the added conductive attenuation along the longer paths off the vertical direction. Field tests in water and glacial ice and laboratory observations show good agreement with the E-plane model results but suggest that the H-plane directivity is strongly affected by the separation between transmit and receive antennas and by the range.
The canarias einstein_ring_a_newly_discovered_optical_einstein_ringSérgio Sacani
We report the discovery of an optical Einstein Ring in the Sculptor constellation,
IAC J010127-334319, in the vicinity of the Sculptor Dwarf Spheroidal Galaxy. It is
an almost complete ring ( 300◦) with a diameter of 4.5 arcsec. The discovery was
made serendipitously from inspecting Dark Energy Camera (DECam) archive imaging
data. Confirmation of the object nature has been obtained by deriving spectroscopic
redshifts for both components, lens and source, from observations at the 10.4 m Gran
Telescopio CANARIAS (GTC) with the spectrograph OSIRIS. The lens, a massive
early-type galaxy, has a redshift of z = 0.581 while the source is a starburst galaxy
with redshift of z = 1.165. The total enclosed mass that produces the lensing effect
has been estimated to be Mtot = (1.86 ± 0.23) · 1012M⊙.
Design of Non-Uniform Linear Antenna Arrays Using Dolph- Chebyshev and Binomi...IJERA Editor
This paper explores the analytical methods of synthesizing linear antenna arrays. The synthesis employed is
based on non-uniform methods. In particular, the Dolph-Chebyshev and binomial methods are used, so as to
improve the directivity of the array and to reduce the level of the secondary lobes by adjusting the geometrical
and electric parameters of the array. The radiation patterns, the directivity, and the array factors of the uniform
and the non-uniform methods are presented. It is shown that the Chebyshev arrays have better directivity than
binomial arrays for the same number of elements and separation distance, while binomial arrays have very low
side lobes compared with Chebyshev and uniform excitation arrays. Finally, numerical results of both methods
are analyzed and compared.
An absorption profile centred at 78 megahertz in the sky-averaged spectrumSérgio Sacani
After stars formed in the early Universe, their ultraviolet light is
expected, eventually, to have penetrated the primordial hydrogen
gas and altered the excitation state of its 21-centimetre hyperfine
line. This alteration would cause the gas to absorb photons from
the cosmic microwave background, producing a spectral distortion
that should be observable today at radio frequencies of less than
200 megahertz1. Here we report the detection of a flattened
absorption profile in the sky-averaged radio spectrum, which is
centred at a frequency of 78 megahertz and has a best-fitting fullwidth
at half-maximum of 19 megahertz and an amplitude of 0.5
kelvin. The profile is largely consistent with expectations for the
21-centimetre signal induced by early stars; however, the best-fitting
amplitude of the profile is more than a factor of two greater than
the largest predictions2. This discrepancy suggests that either the
primordial gas was much colder than expected or the background
radiation temperature was hotter than expected. Astrophysical
phenomena (such as radiation from stars and stellar remnants) are
unlikely to account for this discrepancy; of the proposed extensions
to the standard model of cosmology and particle physics, only
cooling of the gas as a result of interactions between dark matter
and baryons seems to explain the observed amplitude3. The lowfrequency
edge of the observed profile indicates that stars existed
and had produced a background of Lyman-α photons by 180 million
years after the Big Bang. The high-frequency edge indicates that
the gas was heated to above the radiation temperature less than
100 million years later.
Direct detection of a break in the teraelectronvolt cosmic-ray spectrum of el...Sérgio Sacani
High-energy cosmic-ray electrons and positrons (CREs), which
lose energy quickly during their propagation, provide a probe of
Galactic high-energy processes1–7 and may enable the observation
of phenomena such as dark-matter particle annihilation or
decay8–10. The CRE spectrum has been measured directly up to
approximately 2 teraelectronvolts in previous balloon- or spaceborne
experiments11–16, and indirectly up to approximately 5
teraelectronvolts using ground-based Cherenkov γ-ray telescope
arrays17,18. Evidence for a spectral break in the teraelectronvolt
energy range has been provided by indirect measurements17,18,
although the results were qualified by sizeable systematic
uncertainties. Here we report a direct measurement of CREs in the
energy range 25 gigaelectronvolts to 4.6 teraelectronvolts by the
Dark Matter Particle Explorer (DAMPE)19 with unprecedentedly
high energy resolution and low background. The largest part of
the spectrum can be well fitted by a ‘smoothly broken power-law’
model rather than a single power-law model. The direct detection of
a spectral break at about 0.9 teraelectronvolts confirms the evidence
found by previous indirect measurements17,18, clarifies the behaviour
of the CRE spectrum at energies above 1 teraelectronvolt and sheds
light on the physical origin of the sub-teraelectronvolt CREs.
Marchés financiers et Mouvement brownien Peut-on rendre compte des fluctuatio...Ahmed Ammar Rebai PhD
Le mouvement brownien (ou mouvement aléatoire des particules dans un fluide) m'a toujours
intrigué. J'ai vu qu'il était à la base de la plupart des modèles de prix en finance. Je me suis donc
décidé à approfondir le sujet.
Le mouvement brownien est provoqué par les chocs aléatoires des particules qui constituent le
fluide du fait de l'agitation thermique. De même, on peut rendre compte de l'évolution des prix sur
un marché financier par les interactions des agents boursiers. Le milieu boursier est ainsi le figuré
d'un milieu fluide. C'est pourquoi mon Tipe est en adéquation avec le thème milieux.
Liste des projets TIPE (Travail d'Initiative Personnelle Encadré) Ahmed Ammar Rebai PhD
J'ai encadré une soixantaine d'étudiants en classes préparatoires aux grandes écoles d'ingénieurs (CPGE) dans leurs projets de TIPE portant sur le thème: Milieux, interfaces, interactions, ruptures, homogénéité.
Le co-encadrement a été assuré par Monsieur Edouard-Roger Tantart, professeur agrégé de physique en math-spé à Saint-Louis Paris.
L'encadrement a été réalisé dans les locaux de l'école d'ingénieurs Esprit à située à Tunis.
Les étudiants viennent de différents horizons: on trouve les tunisiens, les français, les ivoiriens, les mauritaniens, les camerounais, les burkinabé.
Le document contient l'énoncé de l'épreuve de modélisation mathématiques.informatique pour la banque d'écoles Agro/Véto 2017. La correction se trouve sur le même site.
Correction partie 1,2 et début 3 Epreuve de mathématiques informatique Banque...Ahmed Ammar Rebai PhD
Ce fichier contient une correction détaillée de l'épreuve de mathématiques-informatique Agro/Véto 2017 BCPST 2. Pour l'instant, j'ai mis la partie 1, 2 et le début de la partie 3. Le sujet peut être utilisé par les étudiants en L3 maths/éco puisqu'il traite le problème de régression linéaire avec les probabilités et les estimateurs statistiques.
Méthodes pour les concours des classes préparatoires PC PC* PSI PSI* mais ils pourront servir aussi pour les MP MP*: je suis en train de préparer des méthodes pour eux.
Ill-posedness formulation of the emission source localization in the radio- d...Ahmed Ammar Rebai PhD
To contact the authors : tarek.salhi@gmail.com and ahmed.rebai2@gmail.com
In the field of radio detection in astroparticle physics, many studies have shown the strong dependence of the solution of the radio-transient sources localization problem (the radio-shower time of arrival on antennas) such solutions are purely numerical artifacts. Based on a detailed analysis of some already published results of radio-detection experiments like : CODALEMA 3 in France, AERA in Argentina and TREND in China, we demonstrate the ill-posed character of this problem in the sens of Hadamard. Two approaches have been used as the existence of solutions degeneration and the bad conditioning of the mathematical formulation problem. A comparison between experimental results and simulations have been made, to highlight the mathematical studies. Many properties of the non-linear least square function are discussed such as the configuration of the set of solutions and the bias.
Étude de l'énergie et du point d'émission radio des rayons cosmiques détectés...Ahmed Ammar Rebai PhD
Les rayons cosmiques sont des particules chargées qui bombardent la terre en permanence. Le but de l’expérience CODALEMA, installée à l’observatoire de radioastronomie de Nançay (France), est d’étudier la radiodétection des rayons cosmiques d’ultra-haute énergie. Le dispositif initial utilise en coïncidence un réseau des détecteurs de particules et un réseau d’antennes. Utilisant cet appareillage, une nouvelle analyse visant à estimer l’énergie de la gerbe à partir des données radio est présentée. Nous déduisons qu’une résolution en énergie meilleure que 20% peut être atteinte et que, non seulement la force de Lorentz, mais aussi une contribution proportionnelle à la charge totale produite dans la gerbe atmosphérique joue un rôle significatif dans l’amplitude du champ électrique mesuré. Depuis 2011, un nouveau réseau de détection radio, constitué de 60 stations autonomes auto-déclenchées est en déploiement autour du dispositif initial. Ce développement conduit à des défis spécifiques en termes d’identification des gerbes atmosphériques. Concernant la localisation de la source de l’émission radio, nous montrons que ce problème est mal-posé au sens de Hadamard.
Overview of the fundamental roles in Hydropower generation and the components involved in wider Electrical Engineering.
This paper presents the design and construction of hydroelectric dams from the hydrologist’s survey of the valley before construction, all aspects and involved disciplines, fluid dynamics, structural engineering, generation and mains frequency regulation to the very transmission of power through the network in the United Kingdom.
Author: Robbie Edward Sayers
Collaborators and co editors: Charlie Sims and Connor Healey.
(C) 2024 Robbie E. Sayers
Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
Instead of buying and hoping for the best, we can use data science to help us predict which products may be good fits for us. It includes various function programs to do the above mentioned tasks.
Data file handling has been effectively used in the program.
The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
CFD Simulation of By-pass Flow in a HRSG module by R&R Consult.pptxR&R Consult
CFD analysis is incredibly effective at solving mysteries and improving the performance of complex systems!
Here's a great example: At a large natural gas-fired power plant, where they use waste heat to generate steam and energy, they were puzzled that their boiler wasn't producing as much steam as expected.
R&R and Tetra Engineering Group Inc. were asked to solve the issue with reduced steam production.
An inspection had shown that a significant amount of hot flue gas was bypassing the boiler tubes, where the heat was supposed to be transferred.
R&R Consult conducted a CFD analysis, which revealed that 6.3% of the flue gas was bypassing the boiler tubes without transferring heat. The analysis also showed that the flue gas was instead being directed along the sides of the boiler and between the modules that were supposed to capture the heat. This was the cause of the reduced performance.
Based on our results, Tetra Engineering installed covering plates to reduce the bypass flow. This improved the boiler's performance and increased electricity production.
It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
Explore the innovative world of trenchless pipe repair with our comprehensive guide, "The Benefits and Techniques of Trenchless Pipe Repair." This document delves into the modern methods of repairing underground pipes without the need for extensive excavation, highlighting the numerous advantages and the latest techniques used in the industry.
Learn about the cost savings, reduced environmental impact, and minimal disruption associated with trenchless technology. Discover detailed explanations of popular techniques such as pipe bursting, cured-in-place pipe (CIPP) lining, and directional drilling. Understand how these methods can be applied to various types of infrastructure, from residential plumbing to large-scale municipal systems.
Ideal for homeowners, contractors, engineers, and anyone interested in modern plumbing solutions, this guide provides valuable insights into why trenchless pipe repair is becoming the preferred choice for pipe rehabilitation. Stay informed about the latest advancements and best practices in the field.
Hierarchical Digital Twin of a Naval Power SystemKerry Sado
A hierarchical digital twin of a Naval DC power system has been developed and experimentally verified. Similar to other state-of-the-art digital twins, this technology creates a digital replica of the physical system executed in real-time or faster, which can modify hardware controls. However, its advantage stems from distributing computational efforts by utilizing a hierarchical structure composed of lower-level digital twin blocks and a higher-level system digital twin. Each digital twin block is associated with a physical subsystem of the hardware and communicates with a singular system digital twin, which creates a system-level response. By extracting information from each level of the hierarchy, power system controls of the hardware were reconfigured autonomously. This hierarchical digital twin development offers several advantages over other digital twins, particularly in the field of naval power systems. The hierarchical structure allows for greater computational efficiency and scalability while the ability to autonomously reconfigure hardware controls offers increased flexibility and responsiveness. The hierarchical decomposition and models utilized were well aligned with the physical twin, as indicated by the maximum deviations between the developed digital twin hierarchy and the hardware.
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
Final project report on grocery store management system..pdf
Some recent results of the CODALEMA experiment
1. SF2A 2011
G. Alecian, K. Belkacem, S. Collin, R. Samadi and D. Valls-Gabaud (eds)
SOME RECENT RESULTS OF THE CODALEMA EXPERIMENT
Rebai, A.1 and the CODALEMA collaboration2
Abstract. Codalema is one of the experiments devoted to the detection of ultra high energy cosmic
rays by the radio method. The main objective is to study the features of the radio signal induced by the
development in the atmosphere of extensive air showers (EAS) generated by cosmic rays in the energy range
of 1016
-1018
eV . After a brief presentation of the detector features, the main results obtained are reported
(emission mechanism, lateral distribution of the electric field, energy calibration, etc.). The first studies of
the radio wave front curvature are discussed as new preliminary results.
Keywords: UHECR, radiodetection, antennas, radio emission mechanism, EAS
1 Introduction
A century after the discovery of cosmic rays, several fundamental issues related to the nature and the origin
of ultra high energy cosmic rays (UHECR) remain unanswered, despite intensive experimental efforts. The
main difficulty opposing the progress is due to the extremely low flux of UHECR (1 particle/km2
/century
at 1020
eV ) and the present performances of particle detectors arrays and fluorescence telescopes (Abraham
et al. 2010; Abbasi et al. 2010). In the recent decade, the measurement of the radio counterparty of EAS
becomes a promising technique. Many scientific collaborations like CODALEMA in France (Ardouin et al.
2009) and LOPES in Germany (Apel et al. 2010) have demonstrated the feasibility of this method to deduce
the EAS features. The potentialities of the radiodetection resides in several avantages, among them may be
mentioned: the operating duty cycle close to 100%, the sensitivity to the shower longitudinal development in the
atmosphere and the mechanical robustness, the simplicity and the low cost of the antennas. The CODALEMA
experiment is installed at the radio observatory site (Nan¸cay, 47.3◦
N, 2.1◦
E and 137 m above sea level). Its
main goal is to improve the pioneer experimental results (Allan 1971), taking avantage of ultrafast electronic
devices and a quiet radio environment from anthropic transmitters in the detection bandwidth (Ardouin et al.
2006). From the phenomenological point of view, CODALEMA has made progress in the understanding of radio
signal origin, showing that the geomagnetic field is the main actor in radio signal emission via the geomagnetic
mechanism (Ardouin et al. 2009), and showing recently the contribution of a second emission mechanism due to
the shower negative charge excess (Marin 2011). This contribution reports on the last results of the experiment
CODALEMA with updated data set, recalling the observations of the north-south asymmetry and of the energy
correlation. Finally the reconstruction method of the radio wavefront radius of curvature is presented.
2 Experimental situation
The CODALEMA experiment is made of two main arrays of detectors. The first array is built with 24 short
active dipoles antennas distributed on a cross geometry with dimensions 400 m by 600 m. This apparatus is
used to study the EAS radio counterpart. The dipole antenna is made by two radiator arms each 60 cm long at
a height of 1.2 m. The antenna design was optimized to reach an almost isotropic pattern. Low noise amplifier
(LNA) is used to amplify the electric signal. It is conceived to be sensitive to the radio galactic background and
is linear over a wide frequency band from 0.1 MHz up to 230 MHz. The second apparutus is a ground-based
particle detector array formed by 17 plastic scintillators placed on a square with 340 m side. It measures the
primary particle energy and provides the trigger signal to the other detector arrays. The entire acquisition
system (DAQ) is trigged by the passage of secondary particles in coincidence through each of the five central
scintillators.
1 SUBATECH IN2P3-CNRS/Universit´e de Nantes/´Ecole des Mines de Nantes France
2 LESIA, Observatoire de Paris-Meudon France - Station de Radioastronomie de Nan¸cay France
c Soci´et´e Francaise d’Astronomie et d’Astrophysique (SF2A) 2011
arXiv:1211.3273v1[astro-ph.HE]14Nov2012
2. 238 SF2A 2011
3 A North-South asymmetry: a geomagnetic effect signature in the production of the radio signal
CODALEMA is the first experience which has reported a large and stable assymetry in counting rates between
showers coming from north and south (Ardouin et al. 2009; Ravel 2010). This asymmetry has been interpreted
as a signature of the geomagnetic field effect in the radio signal emission process. The local geomagnetic field
B is the main cause of this assymmetry through the action of Lorentz force on the secondary charged particles
via the v ∧ B term. We find that among the 2030 events detected in coincidences with the two arrays: 1708
events coming from the north and 322 coming from the south (see Fig. 1, Left). The respective ratio equal to
0.188 is consistent with the value of 0.17 obtained with a previous statistic used in (Ardouin et al. 2009). A
pure statistical effect is excluded with 15 σ. One can enhance here on the fact that this asymmetry is stable
over time and with different data samples.
Fig. 1. Left: A plot sky showed the arrival directions distribution of detected EAS events. The red dot indicates the
local geomagnetic field (θ = 27◦
,φ = 0◦
). Right: Sky map of the geomagnetic model theoretical prediction based on
the projection of the product v ∧ B on the East-West direction multiplied by the trigger coverage map. The colormap is
normalized to 1.
4 Energy calibration of the Codalema antenna array
The energy of the primary particle Ep is one of the most important parameters for studying EAS. To avoid the
use of the particles detectors array, the radio technique must demonstrate its ability to estimate the primary
particle energy with the information given by the radio signal alone. In this perspective, a study of the correlation
between the shower energy and the electric field created at the shower axis E0 is the natural way to determine
the energy calibration response of the antenna array. In this goal, after sampling the particles density at ground
a NKG lateral distribution is deduced to measure the total number of charged paticles Ne (mostly electrons
and positrons) in the shower front. The energy Ep is deduced from the constant intensity cuts method (CIC).
The procedure gives a relative error equal to 30%. The electric field E0 is determined by the lateral distribution
function (LDF). The Allan formula has been used to fit the radio LDF with an exponential law (Fig. 2) following
this formula:
Ei = E0.exp(−
((xi − xc)2 + (yi − yc)2 − ((xi − xc).cos(φ).sin(θ) + (yi − yc).sin(φ).sin(θ))2)
d0
)
where, θ and φ are respectivly zenithal and azimuthal angles reconstructed by a planar fit. This fit has four
free parameters E0, the LDF decay distance d0 and the radio-shower core coordinates on the ground (xc, yc),
providing the antennas coordinates (xi, yi) and the radio filtered pulse amplitude Ei for each antennas. The
error on E0 has been estimated through a Monte Carlo analysis. It consist of repeating the LDF fit with Ei
values, randomly selected from gaussian probability density function centred on the measured values Ei and a
gaussian standard deviation σi took as the RMS of measured radio noise on the antenna. This Monte Carlo
method enables to explore the entire phase space and thus to estimate the E0 error on a by event basis. At
the end of the procedure a statistical error less than 22 % is deduced. A linear regression is then used to
deduce the correlation coefficients in the (Ep, E0) plan, assuming some hypothesis: (i) The two variables are
represented on a linear scale. (ii) Gaussian errors are used on both observables. (iii) The two observables Ep
3. Recent results of the Codalema Experiment 239
Fig. 2. Radio lateral distributions reconstructed from antenna signals. The full line show the result of an exponential law
fit (Allan formula). Left: We show the lateral distribution of an event detected by 19 antennas. The primary particle
energy is estimated to Ep = 7.97 1016
eV . Error bars correspond to the radio galactic background. In this example, the
signal amplitudes are close to the noise level. Right: We show the lateral distribution of an other event ,detected by 16
antennas, with larger energy Ep = 1.64 1018
eV . In this case, error bars are small compared to signals.
and E0 are assumed to be independent, to cancel the nonlinear covariance term. Results of this procedure is
presented on Fig. 3. It shows that the electric field created at the shower axis E0 is clearly correlated with
Fig. 3. Left: E0 statistical errors σE0
E0
histogram of the LDF fit method. Right: Fit of the correlation between the
primary particle energy Ep and the electric field at the shower axis E0. This study strongly depends on both Ep and E0
errors.
the primary particle energy Ep following the relationship E0 = a.Ep + b. This correlation shows that the radio
signal emitted by EAS seems coherent. An energy calibration relationship can be deduced, with the following
form ER = (1/a).E0 −(b/a) which allows to have a radio estimation ER of the energy through the radio method
once we have measured E0. It is conceivable that for a future autonomous antennas array, we can measure the
primary particle energy only with a pure radio observable.
5 Radius of curvature reconstruction with CODALEMA
Because theoretical developments indicate that the radio signal shape depends on the shower longitudinal
development, it is waited that the wavefront shape provides information on the nature of the primary particle.
In the first step of the CODALEMA’s analysis, the wavefront was assimilated to a plan determined by a simple
planar fit using the arrival times and locations of each tagged antenna. More detailed studies indicates today
(Fig. 4. Left) that the measured wavefront differs slightly from the plan in most cases and that it exhibits a curved
geometry, favoring the idea of a privileged center for the radio emission during the shower development (Rebai
2010; Schroder 2011). To take into account of these experimental observations, one of the simplest hypothesis
4. 240 SF2A 2011
is to assume that the maximum of the filtered pulse is linked to a radio signal emission center located along
the shower axis. This leads to define a curvature radius Rc. Several modelisations suggest that this observable
could then be related to the shower maximum, Xmax, which is directly correlated to the UHECR chemical
composition. This possibility has been investigated using the present data. Our fitting method is based on the
fit of the residue between the real wavefront determined by arrivals times distribution and the planar wavefront.
A parabolic dependence is used to account for the difference. Results of the calculations are presented in Fig. 4.
The distribution of the Rc presents a maximum at 4 km in global aggrement with the waited characteristic
altitude of the emission maximum. However, the tail of the distribution extends up to 20 km. A present time,
the physical interpretation of this long tail is not well understood. This may be due both to a poor estimate of
arrival time and to a biased assessment of the estimated error on its time measurement, an arrival time error of
10 ns is used. Improvement of these points are underway.
Fig. 4. Left: Expected delay versus measured delay. The black line presents the plane wave fit, Despite the 10 ns
error bars on both axes, many points are located far from the line, which shows that the wavefront differs from a plane.
Right: The histogram of the radius of curvature Rc distribution for 1010 selected events. The distribution maximum is
located at 4 km.
6 Conclusions
Codalema is installed in a radio quiet environment. This advantage has enabled very high accuracy radio signal
measurements and several progress in the understanding of the radio emission mechanisms like the geomagnetic
field effect or the energy calibration method. A method for the wavefront radius of curvature reconstruction has
been presented. The first analysis of the radius of curvature presented shows extremely interesting perspectives
with the aim of determining the cosmic rays nature. The deduced location of the emission point are in a
satisfactory agreement (for radii less than 10 km) with the waited values, but for the larger curvatures the
values remain poorly understood. Unfortunately the low timing accuracy (< 10 ns) may limit the analysis with
current data. The current array extension which uses standalone radio stations to reach a larger array (1.5 km2
)
will increased the available statistic and improve our interpretations.
This work has been made a part under a grant from R´egion Pays de la Loire. The author wishes to thank the CNRS (Centre
national de la recherche scientifique) for funding his work. The author likes to thank the SF2A week organizers for their hospitality.
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