We present the first measurement of the fluctuations in the number of muons in extensive air showers produced by ultrahigh energy cosmic rays. We find that the measured fluctuations are in good ...agreement with predictions from air shower simulations. This observation provides new insights into the origin of the previously reported deficit of muons in air shower simulations and constrains models of hadronic interactions at ultrahigh energies. Our measurement is compatible with the muon deficit originating from small deviations in the predictions from hadronic interaction models of particle production that accumulate as the showers develop.
The irradiation with 1.2 MeV He+ ions to various fluences was successfully used for modification of graphene oxide (GO). The elemental composition of the GO foils before and after He+ ion irradiation ...was investigated using Rutherford Backscattering Spectrometry and Elastic Recoil Detection Analysis. The chemical composition and structural changes of the GO foil surface were characterized by X-Ray Photoelectron and Raman spectroscopy and changes in the electrical properties was studied by standard two point method. The obtained data indicate the removal of oxygen functionalities and growth of the graphene domains on the GO surface that leads to the improvement of surface conductivity which is a growing function of the ion fluence.
•Graphene Oxide foils were irradiated using 1.2 MeV He+ ions to various fluencies.•The composition and structure of pristine and irradiated GO were investigated.•Reduction of GO foil surface and growth of graphene domains were indicated.•The electric conductivity improvement is a growing function of the ion fluence.
Abstract
A promising energy range to look for angular correlations between cosmic rays of extragalactic origin and their sources is at the highest energies, above a few tens of EeV (1 EeV ≡ 10
18
...eV). Despite the flux of these particles being extremely low, the area of ∼3000 km
2
covered at the Pierre Auger Observatory, and the 17 yr data-taking period of the
Phase
1
of its operations, have enabled us to measure the arrival directions of more than 2600 ultra-high-energy cosmic rays above 32 EeV. We publish this data set, the largest available at such energies from an integrated exposure of 122,000 km
2
sr yr, and search it for anisotropies over the 3.4
π
steradians covered with the Observatory. Evidence for a deviation in excess of isotropy at intermediate angular scales, with ∼15° Gaussian spread or ∼25° top-hat radius, is obtained at the 4
σ
significance level for cosmic-ray energies above ∼40 EeV.
We present measurements of microwave emission from an electron-beam induced air plasma performed at the 3 MeV electron Van de Graaff facility of the Argonne National Laboratory. Results include the ...emission spectrum between 1 and 15 GHz, the polarization of the microwave radiation and the scaling of the emitted power with respect to beam intensity. MAYBE measurements provide further insight on microwave emission from extensive air showers as a novel detection technique for Ultra-High Energy Cosmic Rays.
You The Air Microwave Yield (AMY) experiment investigate the molecular bremsstrahlung radiation emitted in the GHz frequency range from an electron beam induced air-shower. The measurements have been ...performed at the Beam Test Facility (BTF) of Frascati INFN National Laboratories with a 510 MeV electron beam in a wide frequency range between 1 and 20 GHz. We present the apparatus and the results of the tests performed.
We present a measurement of the cosmic-ray spectrum above 100 PeV using the part of the surface detector of the Pierre Auger Observatory that has a spacing of 750 m. An inflection of the spectrum is ...observed, confirming the presence of the so-called
second-knee
feature. The spectrum is then combined with that of the 1500 m array to produce a single measurement of the flux, linking this spectral feature with the three additional breaks at the highest energies. The combined spectrum, with an energy scale set calorimetrically via fluorescence telescopes and using a single detector type, results in the most statistically and systematically precise measurement of spectral breaks yet obtained. These measurements are critical for furthering our understanding of the highest energy cosmic rays.
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