6,519 research outputs found
Electronic phase separation near the superconductor-insulator transition of Nd1+xBa2−xCu3O7−δ thin films studied by an electric-field-induced doping effect
We report a detailed study of the transport properties of Nd(1+x)Ba(2-x)Cu(3)O(7-delta) thin films with doping changed by field effect. The data cover the whole superconducting to insulating transition and show remarkable Similarities with the effect of chemical doping in high critical temperature superconductors. The results suggest that the add-on of carriers is accompanied by an electronic phase separation, independent on the details of the doping mechanism
Maria, Mari! : My Marie
https://digitalcommons.library.umaine.edu/mmb-ps/1247/thumbnail.jp
Role of interband scattering in neutron irradiated MgB thin films by Scanning Tunneling Spectroscopy measurements
A series of MgB thin films systematically disordered by neutron
irradiation have been studied by Scanning Tunneling Spectroscopy. The c-axis
orientation of the films allowed a reliable determination of local density of
state of the band. With increasing disorder, the conductance peak moves
towards higher voltages and becomes lower and broader, indicating a monotonic
increase of the gap and of the broadening parameter. These results are
discussed in the frame of two-band superconductivity.Comment: The text will be submitted in Latex format, and the corresponding pdf
file should take 6 pages. There are 5 figures (eps files submitted) and 1
tabl
A teaser made simple: a didactic measurement of the spectral answer of a human-eye-calibrated lux meter
A simple didactic experiment has been designed and realized, in order to illustrate to undergraduate students in scientific faculties some basic concepts lying behind the fundamentals of geometrical optics. The spectral response of a human-eye-calibrated lux meter was measured using a very trivial experimental arrangement. The white light of a halogen lamp was decomposed into its spectral components through a diffraction grating, so that collecting the radiation at different dispersion angles allowed one to measure the intensity as a function of wavelength. The experiment can be used to effectively illustrate the concepts of spectral distribution, the radiometry versus photometry conversion and photopic response, and the famous historical experience by Herschel on the 'temperature of colours'
First results from an aging test of a prototype RPC for the LHCb Muon System
Recent results of an aging test performed at the CERN Gamma Irradiation
Facility on a single--gap RPC prototype developed for the LHCb Muon System are
presented. The results are based on an accumulated charge of about 0.45
C/cm, corresponding to about 4 years of LHCb running at the highest
background rate. The performance of the chamber has been studied under several
photon flux values exploiting a muon beam. A degradation of the rate capability
above 1 kHz/cm is observed, which can be correlated to a sizeable increase
of resistivity of the chamber plates. An increase of the chamber dark current
is also observed. The chamber performance is found to fulfill the LHCb
operation requirements.Comment: 6 pages, 9 figures, presented at the International Workshop on Aging
Phenomena in Gaseous Detectors'', DESY-Hamburg (Germany), October 200
High quality MgB2 thin films in-situ grown by dc magnetron sputtering
Thin films of the recently discovered magnesium diboride (MgB2) intermetalic
superconducting compound have been grown using a magnetron sputtering
deposition technique followed by in-situ annealing at 830 C. High quality films
were obtained on both sapphire and MgO substrates. The best films showed
maximum Tc = 35 K (onset), a transition width of 0.5 K, a residual resistivity
ratio up to 1.6, a low temperature critical current density Jc > 1 MA/cm2 and
anisotropic critical field with gamma = 2.5 close to the values obtained for
single crystals. The preparation technique can be easily scaled to produce
large area in-situ films.Comment: 7 pages, 4 figure
Una nuova scheda “geologica” per la valutazione degli effetti sismici locali in siti di ubicazione di singoli edifici
A partire dai terremoti del Friuli (1976) e dell’Irpinia-Basilicata (1980) la comunità scientifica ha approntato una serie di strumenti schedografici per il
censimento della vulnerabilità sismica, del danno e dell’agibilità degli edifici, raggiungendo così un duplice risultato: raccolta omogenea di dati
tipologico-strutturali finalizzati alla messa a punto di correlazioni tra i parametri sismologici ed i danni accertati e valutazione del livello di agibilità degli
edifici danneggiati. Invece, dal punto di vista geologico non c’è stata un’analoga attenzione per gli strumenti di rilievo; sebbene nel tempo ne siano stati
predisposti alcuni, essi non sono risultati mai esaustivi, pur considerando le necessarie e inevitabili semplificazioni che devono essere adottate per fare di
una scheda uno strumento pratico, di facile applicazione. Nell’ambito dell’Unità di Ricerca è stato quindi condotto un censimento delle schede di tipo
“geologico” già esistenti, al fine di integrare tutte le informazioni necessarie in un unico strumento schedografico.
La nuova scheda consente la raccolta sistematica e ragionata delle informazioni, permettendo una codifica omogenea delle caratteristiche morfolitologiche
locali e, laddove esistano sufficienti dati, una caratterizzazione geotecnica e geofisica del sottosuolo del sito esaminato.
La nuova scheda proposta, opportunamente compilata, permette di fornire una valutazione qualitativa degli effetti sismici locali ed in particolare
consente, a fronte di sufficienti dati raccolti e rilevati, una prima quantificazione degli effetti di amplificazione attesi (Fa) sulla base delle recenti normative nazionali e regionali di settore
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