We present the results of the search for large-scale anisotropies in the arrival directions of cosmic rays performed with the KASCADE-Grande experiment at energies higher than eV. To eliminate ...spurious anisotropies due to atmospheric or instrumental effects we apply the east-west method. We show, using the solar time distribution of the number of counts, that this technique allow us to remove correctly the count variations not associated to real anisotropies. By applying the east-west method we obtain the distribution of number of counts in intervals of 20 minutes of sidereal time. This distribution is then analyzed by searching for a dipole component; the significance of the amplitude of the first harmonic is 3.5 , therefore, we derive its upper limit. The phase of the first harmonic is determined with an error of a few hours and is in agreement with the measurements obtained in the 1014 < E < 2 × 1015 eV energy range by the EAS-TOP, IceCube, and IceTop experiments. This supports the hypothesis of a change of the phase of the first harmonic at energies greater than ∼2 × 1014 eV.
The Cherenkov Telescope Array (CTA) is a world-wide project to build a new generation ground-based gamma-ray instrument operating in the energy range from some tens of GeV to above 100 TeV. To ensure ...full sky coverage CTA will consist of two arrays of Imaging Atmospheric Cherenkov Telescopes (IACTs), one in the southern hemisphere and another one in the northern hemisphere. CTA has just completed the design phase and it is entering in the pre-production one that includes the development of telescope precursor mini-arrays. ASTRI is an ongoing project, to develop and install at the southern CTA site one of such mini-arrays composed by nine dual-mirror small size telescopes equipped with an innovative camera based on silicon photomultiplier sensors. The end-to-end telescope prototype, named ASTRI SST-2M, has been recently inaugurated at the Serra La Nave observing station, on Mount Etna, Italy. ASTRI SST-2M expected performance has been carefully studied using a full Monte Carlo simulation of the shower development in the atmosphere and detector response. Simulated data have been analyzed using the traditional Hillas moment analysis to obtain the expected angular and energy resolution. Simulation results, together with the comparison with the available experimental measurements, are shown.
This paper introduces a modeling approach aimed at the management of groundwater resources based on a hybrid multiobjective paradigm, namely Evolutionary Polynomial Regression. Multiobjective ...modeling in hybrid evolutionary computing enables the user (a) to find a set of feasible symbolic models, (b) to make a robust choice of models and (c) to improve computational efficiency, simultaneously developing a set of models with diverse structural parsimony levels. Moreover, this methodology appears to be well suited to those cases where process input and the boundary conditions are not easily accessible. The multiobjective approach is based on the Pareto dominance criterion and it is fully integrated into the Evolutionary Polynomial Regression paradigm. This approach proves to be effective for modeling groundwater systems, which usually requires (a) accurate analyses of the underlying physical phenomena, (b) reliable forecasts under different hypothetical scenarios and (c) good generalization features of the models identified. For these reasons it is important to construct easily interpretable models which are specialized for well defined purposes. The proposed methodology is tested on a case study aimed at determining the dynamic relationship between rainfall depth and water table depth for a shallow unconfined aquifer located in southeast Italy.
The KASCADE-Grande observatory was a ground-based air shower array dedicated to study the energy and composition of cosmic rays in the energy interval
E
= 1 PeV –1 EeV. The experiment consisted of ...different detector systems which allowed the simultaneous measurement of distinct components of air showers (EAS), such as the muon content. In this contribution, we study the total muon number and the lateral density distribution of muons in EAS detected by KASCADE-Grande as a function of the zenith angle and the total number of charged particles. The attenuation length of the muon content of EAS is also measured. The results are compared with the predictions of the SIBYLL 2.3 high-energy hadronic interaction model.
The nature of ultrahigh-energy cosmic rays (UHECRs) at energies >1020 eV remains a mystery. They are likely to be of extragalactic origin, but should be absorbed within ∼50 Mpc through interactions ...with the cosmic microwave background. As there are no sufficiently powerful accelerators within this distance from the Galaxy, explanations for UHECRs range from unusual astrophysical sources to exotic string physics. Also unclear is whether UHECRs consist of protons, heavy nuclei, neutrinos or γ-rays. To resolve these questions, larger detectors with higher duty cycles and which combine multiple detection techniques are needed. Radio emission from UHECRs, on the other hand, is unaffected by attenuation, has a high duty cycle, gives calorimetric measurements and provides high directional accuracy. Here we report the detection of radio flashes from cosmic-ray air showers using low-cost digital radio receivers. We show that the radiation can be understood in terms of the geosynchrotron effect. Our results show that it should be possible to determine the nature and composition of UHECRs with combined radio and particle detectors, and to detect the ultrahigh-energy neutrinos expected from flavour mixing.
Di Pierro F, Settembre R. J Pain Res. 2013;6:497-503. Please note that throughout the article the use of the word "phytosome" should have been "Phytosome®", and the word "Meriva" should have been ..."Meriva®". Phytosome® and Meriva® are trademarks duly registered by Indena Spa, Milan, Italy.Read the original article
The Large Area Telescope (LAT) on the Fermi satellite is expected to publish a catalogue with more than 100 Gamma-Ray Bursts (GRBs) detected above 100 MeV thanks to a new detection algorithm and a ...new event reconstruction. This work aims at revising the prospects for GRB alerts with the Cherenkov Telescope Array (CTA) based on the new LAT results. We start considering the simulation of the observations with the full CTA of two extremely bright events, the long GRB 130427A and the short GRB 090510, then we investigate how these GRBs would be observed by a particular configuration of the array with the telescopes pointing to different directions in what is called the “coupled divergent mode”.
The KASCADE and KASCADE-Grande experiments operated in KIT-Campus North, Karlsruhe (Germany) from 1993 to 2012. The two experiments studied primary cosmic rays in the energy range from 10
14
eV to 10
...18
eV, investigating the change of slope of the spectrum detected at 2 - 4 × 10
15
eV, the so called knee. We briefly review the performance of the experiments and then the main results obtained in the operation of both experiments: the test of hadronic interaction models, the all particle primary spectrum, the elemental composition of primary cosmic rays (with the first claim of a knee-like feature of the heavy primaries spectrum) and the search for large scale anisotropies.
Aims.
The aim of this study is to search for evidence of a common emission engine between radio giant pulses (GPs) and very-high-energy (VHE,
E
> 100 GeV)
γ
-rays from the Crab pulsar.
Methods.
We ...performed 16 h of simultaneous observations of the Crab pulsar at 1.4 GHz with the Effelsberg radio telescope and the Westerbork Synthesis Radio Telescope (WSRT), and at energies above 60 GeV we used the Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) telescopes. We searched for a statistical correlation between the radio and VHE
γ
-ray emission with search windows of different lengths and different time lags to the arrival times of a radio GP. A dedicated search for an enhancement in the number of VHE
γ
-rays correlated with the occurrence of radio GPs was carried out separately for the P1 and P2 phase ranges, respectively.
Results.
In the radio data sample, 99444 radio GPs were detected. We find no significant correlation between the GPs and VHE photons in any of the search windows. Depending on phase cuts and the chosen search windows, we find upper limits at a 95% confidence level on an increase in VHE
γ
-ray events correlated with radio GPs between 7% and 61% of the average Crab pulsar VHE flux for the P1 and P2 phase ranges, respectively. This puts upper limits on the flux increase during a radio GP between 12% and 2900% of the pulsed VHE flux, depending on the search window duration and phase cuts. This is the most stringent upper limit on a correlation between
γ
-ray emission and radio GPs reported so far.
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