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Purpose In the present research, shear-deformable modeling is extended for natural frequency analysis of functionally graded graphene nanoplatelets reinforced cylindrical shell. The main novelty of this work is investigating impact of various distributions of the graphene nanoplatelets and amount of them on the variation in the natural frequencies of the reinforced shell. Furthermore, an investigation on the effect of various boundary conditions on the natural frequency responses is presented. Methods After presenting the effective relations for material properties such as modulus of elasticity, density and Poisson’s ratio, the governing equations of motion are derived based on Hamilton’s principle. The governing equations of motion are analytically solved using the Navier’s technique. The natural frequencies are obtained using a solution of the characteristic equation. Results The results are verified using a comparative study with results from the available literature. The natural frequencies are presented with variation in significant characteristics and parameters of material composition and geometry. The results show that the highest and lowest natural frequencies are obtained for FG-X and FG-O distributions of reinforcement, respectively. Conclusions Furthermore, it is deduced that a 1% addition of the graphene nanoplatelets to the pure matrix leads to a 50% increase in natural frequencies of the cylindrical shell. One can use the results of this analysis to arrive at an optimized design of reinforced structures for application in technical equipment.

The rate of high energy cosmic ray muons as measured underground is shown to be strongly correlated with upper‐air temperatures during short‐term atmospheric (10‐day) events. The effects are seen by correlating data from the MINOS underground detector and temperatures from the European Centre for Medium Range Weather Forecasts during the winter periods from 2003–2007. This effect provides an independent technique for the measurement of meteorological conditions and presents a unique opportunity to measure both short and long‐term changes in this important part of the atmosphere.

After a short review of previous attempts to observe and measure the near-infrared scintillation in liquid argon, we present new results obtained with NIR, a dedicated cryostat at the Fermilab Proton Assembly Building (PAB). The new results give confidence that the near-infrared light can be used as the much needed light signal in large liquid argon time projection chambers.11 pages,

The hybrid design of the Pierre Auger Observatory allows for the measurement of the properties of extensive air showers initiated by ultra-high energy cosmic rays with unprecedented precision. By using an array of prototype underground muon detectors, we have performed the first direct measurement, by the Auger Collaboration, of the muon content of air showers between 2 $\\times$ 1017 and 2 $\\times$ 1018 eV. We have studied the energy evolution of the attenuation-corrected muon density, and compared it to predictions from air shower simulations. The observed densities are found to be larger than those predicted by models. We quantify this discrepancy by combining the measurements from the muon detector with those from the Auger fluorescence detector at 1017.5 eV and 1018 eV. We find that, for the models to explain the data, an increase in the muon density of 38% $±$4%(12%) $±^{21\\%}_{18\\%}$ for EPOS-LHC, and of 50%(53%) $±$4%(13%) $±^{23\\%}_{20\\%}$ for QGSJETII-04, is respectively needed.

The hybrid design of the Pierre Auger Observatory allows for the measurement of the properties of extensive air showers initiated by ultra-high energy cosmic rays with unprecedented precision. By using an array of prototype underground muon detectors, we have performed the first direct measurement, by the Auger Collaboration, of the muon content of air showers between$$2\\times 10^{17}$$2 × 10 17 and$$2\\times 10^{18}$$2 × 10 18 eV. We have studied the energy evolution of the attenuation-corrected muon density, and compared it to predictions from air shower simulations. The observed densities are found to be larger than those predicted by models. We quantify this discrepancy by combining the measurements from the muon detector with those from the Auger fluorescence detector at$$10^{{17.5}}\\, {\\mathrm{eV}} $$10 17.5 eV and$$10^{{18}}\\, {\\mathrm{eV}} $$10 18 eV . We find that, for the models to explain the data, an increase in the muon density of$$38\\%$$38 %$$\\pm 4\\% (12\\%)$$± 4 % ( 12 % )$$\\pm {}^{21\\%}_{18\\%}$$± 18 % 21 % for EPOS-LHC , and of$$50\\% (53\\%)$$50 % ( 53 % )$$\\pm 4\\% (13\\%)$$± 4 % ( 13 % )$$\\pm {}^{23\\%}_{20\\%}$$± 20 % 23 % for QGSJetII-04 , is respectively needed.

Energy-dependent patterns in the arrival directions of cosmic rays are searched for using data of the Pierre Auger Observatory. We investigate local regions around the highest-energy cosmic rays with E ≥ 6 × 10 19 eV by analyzing cosmic rays with energies above E ≥ 5 × 10 18 eV arriving within an angular separation of approximately 15 ∘ . We characterize the energy distributions inside these regions by two independent methods, one searching for angular dependence of energy-energy correlations and one searching for collimation of energy along the local system of principal axes of the energy distribution. No significant patterns are found with this analysis. The comparison of these measurements with astrophysical scenarios can therefore be used to obtain constraints on related model parameters such as strength of cosmic-ray deflection and density of point sources.

The Liquid Argon Time Projection Chambers (LArTPCs) are a choice for the next generation of large neutrino detectors due to their optimal performance in particle tracking and calorimetry. The detection of Argon scintillation light plays a crucial role in the event reconstruction as well as the time reference for non-beam physics such as supernovae neutrino detection and baryon number violation studies. In this contribution, we present the current R&D work on the ARAPUCA (Argon R&D Advanced Program at UNICAMP), a light trap device to enhance Ar scintillation light collection and thus the overall performance of LArTPCs. The ARAPUCA working principle is based on a suitable combination of dichroic filters and wavelength shifters to achieve a high efficiency in light collection. We discuss the operational principles, the last results of laboratory tests and the application of the ARAPUCA as the alternative photon detection system in the protoDUNE detector.

Since the 1970s it has been known that noble gases scintillate in the near infrared (NIR) region of the spectrum (0.7 \\(\\mu\\)m < \\(\\lambda\\); < 1.5\\(\\mu\\)m). More controversial has been the question of the NIR light yield for condensed noble gases. We first present the motivation for using the NIR scintillation in liquid argon detectors, then briefly review early as well as more recent efforts and finally show encouraging preliminary results of a test performed at Fermilab.

The observation of ultrahigh energy neutrinos (UHEνs) has become a priority in experimental astroparticle physics. UHEνs can be detected with a variety of techniques. In particular, neutrinos can interact in the atmosphere (downward-going ν) or in the Earth crust (Earth-skimming ν), producing air showers that can be observed with arrays of detectors at the ground. With the surface detector array of the Pierre Auger Observatory we can detect these types of cascades. The distinguishing signature for neutrino events is the presence of very inclined showers produced close to the ground (i.e., after having traversed a large amount of atmosphere). In this work we review the procedure and criteria established to search for UHEνs in the data collected with the ground array of the Pierre Auger Observatory. This includes Earth-skimming as well as downward-going neutrinos. No neutrino candidates have been found, which allows us to place competitive limits to the diffuse flux of UHEνs in the EeV range and above.

Using data taken by SELEX during the 1996–1997 fixed target run at Fermilab, we study the production of charmed hadrons on copper and carbon targets with  Σ − , p , π − , and π + beams. Parametrizing the dependence of the inclusive production cross section on the atomic number A as A α , we determine α for  D + , D 0 , D s + , D + (2010), Λ c + , and their respective anti-particles, as a function of their transverse momentum p t and scaled longitudinal momentum  x F . Within our statistics there is no dependence of α on x F for any charm species for the interval 0.1< x F <1.0. The average value of α for charm production by pion beams is α meson =0.850±0.028. This is somewhat larger than the corresponding average α baryon =0.755±0.016 for charm production by baryon beams ( Σ − , p ).