11,029 research outputs found
Anisotropy studies around the galactic centre at EeV energies with the Auger Observatory
No full textData from the Pierre Auger Observatory are analyzed to search for anisotropies near the direction of the Galactic Centre at EeV energies. The exposure of the surface array in this part of the sky is already significantly larger than that of the fore-runner experiments. Our results do not support previous findings of localized excesses in the AGASA and SUGAR data. We set an upper bound on a point-like flux of cosmic rays arriving from the Galactic Centre which excludes several scenarios predicting sources of EeV neutrons from Sagittarius A. Also the events detected simultaneously by the surface and fluorescence detectors (the ‘hybrid’ data set), which have better pointing accuracy but are less numerous than those of the surface array alone, do not show any significant localized excess from this direction.http://www.elsevier.com/wps/find/journaldescription.cws_home/523319/description#descriptio
The Pierre Auger Observatory III: Other Astrophysical Observations - Collection of papers in http://arxiv.org/ftp/arxiv/papers/1107/1107.4805.pdf
No full textContributions of the Auger Collaboration to the 32nd International Cosmic Ray Conference, Beijing, August, 2011: Astrophysical observations of ultra-high-energy cosmic rays with the Pierre Auger Observator
The Pierre Auger Observatory I: The Cosmic Ray Energy Spectrum and Related Measurements - Collection of papers in http://arxiv.org/ftp/arxiv/papers/1107/1107.4809.pdf
No full textContributions of the Auger Collaboration to the 32nd International Cosmic Ray Conference, Beijing, August, 2011: Studies of the cosmic ray energy spectrum at the highest energies with the Pierre Auger Observatory
The Pierre Auger Observatory II: Studies of Cosmic Ray Composition and Hadronic Interaction models - Collection of papers in http://arxiv.org/ftp/arxiv/papers/1107/1107.4804.pdf
No full textContributions of the Auger Collaboration to the 32nd International Cosmic Ray Conference, Beijing, August, 2011: Studies of the composition of the highest energy cosmic rays with the Pierre Auger Observatory, including examination of hadronic physics effects on the structure of extensive air showers
Some experiences with bored and auger piles in Naples area
No full textExperimental evidence on load-settlement behaviour of foundation piles in the volcanic soils of Naples area is presented and discussed.
The variability of behaviour among piles of the same foundation seems independent of the pile technology (bored, driven, auger piles). The behaviour of auger piles is generally intermediate between those of bored and driven piles; the results of a number of proof load tests, performed on piles belonging to two recent auger pile foundations, confirm this finding. Eventually, the results of load tests carried out up to failure on large diameter bored piles, equipped with a preloading cell at the base and instrumented along the shaft by means of strain gages extensometers, are presented
Symmetry characterization of unoccupied states in thick alkaline layers by spin-resolved Auger electron spectroscopy using primary excitation by circularly polarized light
No full textStoppmanns P, David R, Müller N, Heinzmann U, Grieb H, Noffke J. Symmetry characterization of unoccupied states in thick alkaline layers by spin-resolved Auger electron spectroscopy using primary excitation by circularly polarized light. Journal of physics: condensed matter. 1994;6(23):4225-4232.CVV Auger electrons emitted from K, Rb and Cs layers are studied using spin-resolved spectroscopy. Oriented 3p, 4p and 5p hole states are excited by circularly polarized radiation in normal incidence. The photon energies range from 12 to 24 eV. With all three materials, the degree and sign of the Auger electron spin polarization vary with the photon energy. As an atomic model of the Auger process predicts, and as a comparison of measurements with the calculated densities of states shows, the spin polarization is essentially determined by the symmetry of the final states reached in the primary (photo)excitation. Just above the excitation threshold, the preferential spin direction of the Auger electrons is measured to be parallel to the spin of the exciting photons corresponding to a predominantly s-like symmetry of the unoccupied final states reached by the excitation. At higher photon energies the preferential spin direction changes to be antiparallel to the photon spin, corresponding to the mainly d-like symmetry of unoccupied states reached by the excitation
Auger-induced charge migration
No full textNovel perspectives of controlling molecular systems have recently arisen from the possibility of generating attosecond pulses in the ultraviolet regime and tailoring electron dynamics in its natural time scale. The cornerstone mechanism is the so-called charge migration, he production of a coherent charge transfer with subfemtosecond oscillations across a molecule. Typically, charge migration is induced by the ionization of valence molecular orbitals. However, recent technological developments allow the generation of attosecond pulses in the x-ray regime. In this case, the absorption of photons creates core-hole states. In light elements, core-hole states mainly decay by Auger processes that, driven by electron correlations, involve valence orbitals. We theoretically demonstrate in a fluoroacetylene molecule a double-hole charge migration triggered by attosecond core-electron photoionization, followed by Auger electron relaxations. This opens a new route for inducing with x rays charge transfer processes in the subfemtosecond time scale
Attribution of Three Works to John Viccars (c. 1604–53?)
No full textThis is a pre-copyedited, author-produced PDF of an article accepted for publication in Notes and Queries following peer review. The version of record [Peter Auger, Attribution of Three Works to John Viccars (c. 1604–53?), Notes and Queries (2014) 61 (3): 362-366] is available online at: http://intl-nq.oxfordjournals.org/content/61/3/36
The Pierre Auger Observatory scaler mode for the study of solar activity modulation of galactic cosmic rays
No full textSince data-taking began in January 2004, the Pierre Auger Observatory has been recording the count rates of low energy secondary cosmic ray particles for the self-calibration of the ground detectors of its surface detector array. After correcting for atmospheric effects, modulations of galactic cosmic rays due to solar activity and transient events are observed. Temporal variations related with the activity of the heliosphere can be determined with high accuracy due to the high total count rates. In this study, the available data are presented together with an analysis focused on the observation of Forbush decreases, where a strong correlation with neutron monitor data is found
The Auger spectrum of benzene
No full textWe present an ab initio computational study of the Auger electron spectrum of
benzene. Auger electron spectroscopy exploits the Auger-Meitner effect and, although
it is established as an analytic technique, the theoretical modeling of molecular
Auger spectra from first principles remain challenging. Here, we use coupled-cluster
and equation-of-motion coupled-cluster theory combined with two approaches
to describe the decaying nature of core-ionized states: (i) Feshbach-Fano resonance
theory and (ii) the method of complex basis functions. The spectra computed with
these two approaches are in excellent agreement with each other and also agree
well with experimental Auger spectra of benzene. The Auger spectrum of benzene
features two well-resolved peaks at Auger electron energies above 260 eV that correspond
to final states with two electrons removed from the 1e1g and 3e2g highest
occupied molecular orbitals. At lower Auger electron energies, the spectrum is less
well resolved and the peaks comprise multiple final states of the benzene dication.
In line with theoretical considerations, singlet decay channels contribute more to the
total Auger intensity than the corresponding triplet decay channels
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