1. Search for Ultra-relativistic Magnetic Monopoles with the Pierre Auger ObservatoryMarko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Toshihiro Fujii, 2015, objavljeni znanstveni prispevek na konferenci Opis: Ultra-relativistic magnetic monopoles, possibly a relic of
phase transitions in the early universe, would deposit an
amount of energy comparable to UHECRs in their passage
through the atmosphere, producing highly distinctive air
shower profiles. We have performed a search for
ultra-relativistic magnetic monopoles in the sample of air
showers with profiles measured by the fluorescence detector of
the Pierre Auger Observatory. No candidate was found to satisfy
our selection criteria and we establish upper limits on the
flux of ultra-relativistic magnetic monopoles - the first from
an UHECR detector - improving over previous results by up to an
order of magnitude.
Najdeno v: osebi
Ključne besede: ultra-relativistic magnetic monopoles, extensive air showers, Pierre Auger Observatory
Objavljeno: 03.03.2016; Ogledov: 3874; Prenosov: 189
 Polno besedilo (188,24 KB) |
2. Structural phases of ordered FePc-nanochains self-assembled on Au(110)Betti Maria Grazia, Pierluigi Gargiani, Carlo Mariani, Roberto Biagi, Jun Fujii, Giorgio Rossi, Andrea Resta, Stefano Fabris, Sara Fortuna, Xavier Torrelles, Manvendra Kumar, Maddalena Pedio, 2012, izvirni znanstveni članek Opis: Iron-phthalocyanine molecules deposited on the Au(110) reconstructed channels assemble into one-dimensional molecular chains, whose spatial distribution evolves into different structural phases at increasing molecular density. The plasticity of the Au channels first induces an ordered phase with a 5×5 symmetry, followed by a second long-range ordered structure composed by denser chains with a 5×7 periodicity with respect to the bare Au surface, as observed in the low-energy electron-diffraction (LEED) and grazing incidence X-ray diffraction (GIXRD) patterns. The geometry of the FePc molecular assemblies in the Au nanorails is determined by scanning tunneling microscopy (STM). For the 5×7 phases, the GIXRD analysis identifies a “4-3” rows profile along the [001] direction in the Au surface and an on-top FePc adsorption site, further confirmed by density functional theory (DFT) calculations. The latter also reveals the electronic mixing of the interface states. The chain assembly is driven by the molecule–molecule interaction and the chains interact with the Au nanorails via the central metal atom, while the chain–chain distance in the different structural phases is primarily driven by the plasticity of the Au surface.
Najdeno v: osebi
Ključne besede: STM, LEED, DFT, density functional theory, phthalocyanine, Au(110), gold, surface
Objavljeno: 13.10.2016; Ogledov: 4039; Prenosov: 0
Polno besedilo (1,33 MB) |
3. A systematic uncertainty on the energy scale of the Telescope Array fluorescence detectorsJ. P. Lundquist, T. Fujii, 2018, objavljeni znanstveni prispevek na konferenci Opis: The Telescope Array experiment (TA) is the largest cosmic-ray detector in the northern hemi-sphere and consists of a surface detector (SD) array, plus three fluorescence detector (FD) stations overlooking the SD. The large field-of-view of an FD allows for reconstruction of the air-shower development in the atmosphere by imaging ultra-violet fluorescence light from atmospheric nitrogen excited by UHECRs. In estimation of the primary energy it is necessary to add to the calorimetric energy observed by the FD a “missing energy”, meaning the fraction of the primary energy that is not deposited by charged particles in the air. We report on the measurement of the missing energy from observed data collected by the TA FD and TA SD, independently of Monte Carlo simulations, using a technique pioneered by the Pierre Auger Observatory. We also address the effect on the energy scale attributed to fluorescence yield parameters.
Najdeno v: osebi
Ključne besede: UHECR, cosmic rays, energy spectrum
Objavljeno: 29.04.2020; Ogledov: 1938; Prenosov: 73
Polno besedilo (4,74 MB) |
