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Register a new userAngular distribution of extensive air showers by TEL array under GELATICA experiment
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Authors
Manana Svanidze
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Extensive Air Showers (EAS) arrival direction distribution is studied by means of a 4-detector installation in Telavi (TEL array), which is a node of GELATICA net in Georgia. The description of EAS arrival zenith angle distribution within the spheric layer model of the atmosphere and exponential absorption of showers with the air path is used. It is shown that the variation of zenith angles upper cutoff boundary allows a stable estimation of showers absorption path.
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The distribution of the angle between the arrival directions of the fronts of consecutive Extensive Air Showers(EAS) with a wide range of a total number of charged particles is studied using the experimental data taken by the EAS 4-detector array TEL in Telavi. The station is a part of the GELATICA net in Georgia (GEorgian Large-area Angle and TIme Coincidence Array), which is devoted to the study of possible correlations in the arrival times and directions of separate EAS events over large distances. It is shown that the aforementioned directions really are in the essentially independent and can be used for investigation of simultaneous correlations of the EAS arrival times and directions.
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.
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 $(3.3pm 1.0)%$ for very inclined air showers at $25, mathrm{m}$ to $(20.3pm 1.3)%$ for almost vertical showers at $225, mathrm{m}$. Both dependencies are in qualitative agreement with theoretical predictions.
TREND50 is a radio detection setup of 50 self-triggered antennas working in the 50-100MHz frequency range and deployed in a radio-quiet valley of the Tianshan mountains (China). TREND50 achieved its goal: the autonomous radiodetection and identification of air showers. Thanks to a dedicated offine selection algorithm, 564 air shower candidates were indeed selected out of $7cdot10^8$ transient radio signals recorded during the 314 live days of data taken during the first two years of operation of this setup (2011 and 2012). This event rate, as well as the distribution of the candidate directions of arrival, is consistent with what is expected from cosmic-ray-induced air showers according to simulations, assuming an additional $sim$20% contamination of the final sample by background events. This result is obtained at the cost of a reduced air shower detection efficiency, estimated to be $sim$3%. This low efficiency is mostly due to the large amount of dead time of the setup. This result paves the way for the GRANDProto35 experiment, the first stage of the GRAND project.
We report on a measurement of thermal neutrons, generated by the hadronic component of extensive air showers (EAS), by means of a small array of EN-detectors developed for the PRISMA project (PRImary Spectrum Measurement Array), novel devices based on a compound alloy of ZnS(Ag) and $^{6}$LiF. This array has been operated within the ARGO-YBJ experiment at the high altitude Cosmic Ray Observatory in Yangbajing (Tibet, 4300 m a.s.l.). Due to the tight correlation between the air shower hadrons and thermal neutrons, this technique can be envisaged as a simple way to estimate the number of high energy hadrons in EAS. Coincident events generated by primary cosmic rays of energies greater than 100 TeV have been selected and analyzed. The EN-detectors have been used to record simultaneously thermal neutrons and the air shower electromagnetic component. The density distributions of both components and the total number of thermal neutrons have been measured. The correlation of these data with the measurements carried out by ARGO-YBJ confirms the excellent performance of the EN-detector.
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