Correction: Batković et al. Axion-like Particle Searches with IACTs. Universe 2021, 7, 185

The authors wish to make the following corrections to their paper [...

Monitoring of the radio galaxy M 87 at Very High Energy with MAGIC during a low emission state between 2012 and 2015

AbstractWe present the preliminary results from observing the nearby radio galaxy M 87 for 156 hours (between the years 2012 and 2015) with the MAGIC telescopes, which lead to a significant very high energy (VHE, E > 100 GeV) detection of the source in quiescent states each year. Our VHE analysis combined with quasi-simultaneous data at other energies (from gamma-rays, X-rays, optical and radio) provides a unique opportunity to study the source variability and its broadband spectral energy distribution, which is found to disfavour a one-zone synchrotron/synchrotron self-Compton model. Therefore, other alternative scenarios for the photon emission are explored. We also find that the VHE emission is compatible with being produced close to the source radio core as previous data already indicated. A detailed paper presenting full results of the observing campaign is in preparation

MAGIC gamma-ray telescopes hunting for neutrinos and their sources

The discovery of an astrophysical flux of high-energy neutrinos by the IceCube Collaboration marks a major breakthrough in the ongoing search for the origin of cosmic rays. Presumably, the neutrinos, together with gamma rays, result from pion decay, following hadronic interactions of protons accelerated in astrophysical objects to ultra-relativistic energies. So far, the neutrino sky map shows no significant indication of astrophysical sources. Here, we report first results from follow-up observations, of sky regions where IceCube has detected muon tracks from energetic neutrinos, using the MAGIC telescopes which are sensitive to gamma rays at TeV energies. Furthermore, we show that MAGIC has the potential to distinguish air showers induced by tau neutrinos from the background of hadronic showers in the PeV-EeV energy range, employing a novel analysis method to the data obtained with high-zenith angle observations.Peer Reviewe

SiNx-induced intermixing in AlInGaAs/InP quantum well through interdiffusion of group III atoms

We analyze the composition profiles within intermixed and non-intermixed AlInGaAs-based multiple quantum wells structures by secondary ion mass spectrometry and observe that the band gap blue shift is mainly attributed to the interdiffusion of In and Ga atoms between the quantum wells and the barriers. Based on these results, several AlInGaAs-based single quantum well (SQW) structures with various compressive strain (CS) levels were grown and their photoluminescence spectra were investigated after the intermixing process involving the encapsulation of thin SiNx dielectric films on the surface followed by rapid thermal annealing. In addition to the annealing temperature, we report that the band gap shift can be also enhanced by increasing the CS level in the SQW. For instance, at an annealing temperature of 850 degrees C, the photoluminescence blue shift is found to reach more than 110 nm for the sample with 1.2%-CS SQW, but only 35 nm with 0.4%-CS SQW. We expect that this relatively larger atomic compositional gradient of In (and Ga) between the compressively strained quantum well and the barrier can facilitate the atomic interdiffusion and it thus leads to the larger band gap shift. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4764856

Search for tau neutrinos with the MAGIC telescopes: improving selection criteria*

MAGIC, a system of two Cherenkov telescopes located at the Roque de los Muchachos Observatory (2200 a.s.l.) in the Canary Island of La Palma, has lately been engaged in an unconventional task: the search for a signature of particle showers in- duced by earth-skimming cosmic tau neutrinos arising from the ocean, in the PeV to EeV energy range. When pointing at the sea, the MAGIC telescopes can collect data in a range of about 5 deg in zenith and 80 deg in azimuth: the analysis of the shower im- ages from 3c30 hours of data, together with the simulations of upward-going tau neutrino showers, shows that the air showers induced by tau neutrinos can be discriminated from the hadronic background coming from a similar direction. We have calculated the point source acceptance and the expected event rates, assuming an incoming \u3bd\u3c4 flux consistent with IceCube measurements, and for a sample of generic neutrino fluxes from photo- hadronic interactions in AGNs and GRBs. A 90% C.L. upper limit on the tau-neutrino point source flux of 2.0 7 10 124 GeV cm 122 s 121 has been obtained. The presented results can also be important for future Cherenkov experiments such as the Cherenkov Telescope Array. This next generation ground-based observatory can have a much better possibility to detect \u3bd\u3c4, given its larger FOV and much larger effective area

InAlAs solar cell on a GaAs substrate employing a graded InxGa1-xAs-InP metamorphic buffer layer

Single junction In0.52Al0.48As solar cells have been grown on a (100) GaAs substrate by employing a 1 mu m thick compositionally graded InxGa1-xAs/InP metamorphic buffer layer to accommodate the 3.9% mismatch. Cells processed from the 0.8 mu m thick InAlAs layers had photovoltaic conversion efficiency of 5% with an open circuit voltage of 0.72 V, short-circuit current density of 9.3 mA/cm(2), and a fill factor of 74.5% under standard air mass 1.5 illumination. The threading dislocation density was estimated to be 3 x 10(8) cm(-2). (C) 2013 American Institute of Physics. (http://dx.doi.org/10.1063/1.4789521