Search results for "AUGER"
showing 10 items of 144 documents
The FRAM robotic telescope for atmospheric monitoring at the Pierre Auger Observatory
2021
FRAM (F/Photometric Robotic Atmospheric Monitor) is a robotic telescope operated at the Pierre Auger Observatory in Argentina for the purposes of atmospheric monitoring using stellar photometry. As a passive system which does not produce any light that could interfere with the observations of the fluorescence telescopes of the observatory, it complements the active monitoring systems that use lasers. We discuss the applications of stellar photometry for atmospheric monitoring at optical observatories in general and the particular modes of operation employed by the Auger FRAM. We describe in detail the technical aspects of FRAM, the hardware and software requirements for a successful operati…
An Indication of Anisotropy in Arrival Directions of Ultra-high-energy Cosmic Rays through Comparison to the Flux Pattern of Extragalactic Gamma-Ray …
2018
A new analysis of the dataset from the Pierre Auger Observatory provides evidence for anisotropy in the arrival directions of ultra-high-energy cosmic rays on an intermediate angular scale, which is indicative of excess arrivals from strong, nearby sources. The data consist of 5514 events above 20 EeV with zenith angles up to 80 deg recorded before 2017 April 30. Sky models have been created for two distinct populations of extragalactic gamma-ray emitters: active galactic nuclei from the second catalog of hard Fermi-LAT sources (2FHL) and starburst galaxies from a sample that was examined with Fermi-LAT. Flux-limited samples, which include all types of galaxies from the Swift-BAT and 2MASS …
Large-scale Cosmic-Ray Anisotropies above 4 EeV Measured by the Pierre Auger Observatory
2018
We present a detailed study of the large-scale anisotropies of cosmic rays with energies above 4 EeV measured using the Pierre Auger Observatory. For the energy bins [4,8] EeV and $E\geq 8$ EeV, the most significant signal is a dipolar modulation in right ascension at energies above 8 EeV, as previously reported. In this paper we further scrutinize the highest-energy bin by splitting it into three energy ranges. We find that the amplitude of the dipole increases with energy above 4 EeV. The growth can be fitted with a power law with index $\beta=0.79\pm 0.19$. The directions of the dipoles are consistent with an extragalactic origin of these anisotropies at all the energies considered. Addi…
Erratum to "Atmospheric effects on extensive air showers observed with the surface detector of the Pierre Auger observatory"[Astroparticle Physics 32…
2010
The Pierre Auger Collaboration... K.B. Barber... J.A. Bellido... R.W. Clay... B.R. Dawson... V.C. Holmes... J. Sorokin... P. Wahrlich... B.J. Whelan... M.G. Winnick... et al.
Origin of atmospheric aerosols at the Pierre Auger Observatory using studies of air mass trajectories in South America
2014
The Pierre Auger Observatory is making significant contributions towards understanding the nature and origin of ultra-high energy cosmic rays. One of its main challenges is the monitoring of the atmosphere, both in terms of its state variables and its optical properties. The aim of this work is to analyze aerosol optical depth $\tau_{\rm a}(z)$ values measured from 2004 to 2012 at the observatory, which is located in a remote and relatively unstudied area of the Pampa Amarilla, Argentina. The aerosol optical depth is in average quite low - annual mean $\tau_{\rm a}(3.5~{\rm km})\sim 0.04$ - and shows a seasonal trend with a winter minimum - $\tau_{\rm a}(3.5~{\rm km})\sim 0.03$ -, and a sum…
Structural properties of the quaternary Heusler alloy Co2Cr1−xFexAl
2007
The quarternary substitutional series Co2Cr1?xFexAl was investigated by means of surface and bulk sensitive techniques in order to exploit its structural and compositional properties. Both bulk and powder samples of the alloy series were investigated to obtain specific information about this material.The long range order was determined by means of x-ray diffraction and neutron diffraction, while the site specific (short range) order was proved by extended x-ray absorption fine structure spectroscopy. The magnetic structure was investigated by M?ssbauer spectroscopy in transmission and scattering modes in order to compare and separate powder and bulk properties. The chemical composition was …
Surface spectroscopic study of the corrosion of ultrathin57Fe-evaporated and Langmuir-Blodgett films in humid SO2 environments
2000
Integral conversion electron Mossbauer spectroscopy (ICEMS), x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and scanning electron microscopy (SEM) have been used to carry out a comparative study of the corrosion resistance against humid SO2-aggressive environments of ultrathin 57Fe films. These films, having a thickness ≤ 2.5 nm, have been prepared by evaporation of 57Fe under vacuum and by 57Fe coating by a Langmuir–Blodgett (LB) technique on SiO2/Si wafers. The results have shown that the corrosion resistance of the evaporated films is similar to that of massive Fe. However, the LB films show a remarkably higher corrosion resistance. Thus, although the Fe films …
Reactivity of H2S and H2S/H2 Mixture With Molybdenum Oxide Thin Films Epitaxied on CoO (100) : Characterization by Rheed and Auger Spectroscopy
2010
Molybdenum-Cobalt composite oxide films were prepared by the evaporation of molybdenum trioxide on a fresh cleaved CoO (100) surface (Thickness = 10 A). The MoO3-CoO interface has been characterized simultaneously by reflexion high electron diffraction (RHEED) and Auger Electron Spectroscopy (AES). The thin film structure and composition depend on the annealing temperature. After a 300°C treatment, metallic cobalt islands nucleate at the interface thin film - CoO (100) and crystallize with the cubic FCC symmetry. After a 700°C treatment cobalt molybdate (a CoMoO4) islands grow. The metastable crystallites are epitaxied on CoO (100). After a 900°C treatment, the thin film consists of flat tw…
Functionalization using biocompatible carboxylated cyclodextrins of iron-based nanoMIL-100
2021
9 pags., 7 figs., 1 tab.
SVET, AFM and AES study of pitting corrosion initiated on MnS inclusions by microinjection
2003
As pitting is a random phenomenon, it is difficult to predict where a pit will appear on the surface and consequently the use of local probes is rendered difficult. In this work, a new method to study pitting corrosion on a MnS inclusion on 316L stainless steel is proposed. It consists in modifying locally the chemistry in its vicinity by injecting with a microcapillary an aggressive solution of NaCl, H2SO4 or HCl. Once a pit appears, scanning vibrating electrode technique (SVET) is used to follow the current fluctuations over and around the pit when the metal is polarized at a passive potential. In another series of experiments the effect of local activation of MnS inclusion was studied ex…