377 research outputs found
Characterization of carbon contamination under ion and hot atom bombardment in a tin-plasma extreme ultraviolet light source
Molecular contamination of a grazing incidence collector for extreme
ultraviolet (EUV) lithography was experimentally studied. A carbon film was
found to have grown under irradiation from a pulsed tin plasma discharge. Our
studies show that the film is chemically inert and has characteristics that are
typical for a hydrogenated amorphous carbon film. It was experimentally
observed that the film consists of carbon (~70 at. %), oxygen (~20 at. %) and
hydrogen (bound to oxygen and carbon), along with a few at. % of tin. Most of
the oxygen and hydrogen are most likely present as OH groups, chemically bound
to carbon, indicating an important role for adsorbed water during the film
formation process. It was observed that the film is predominantly sp3
hybridized carbon, as is typical for diamond-like carbon. The Raman spectra of
the film, under 514 and 264 nm excitation, are typical for hydrogenated
diamond-like carbon. Additionally, the lower etch rate and higher energy
threshold in chemical ion sputtering in H2 plasma, compared to
magnetron-sputtered carbon films, suggests that the film exhibits diamond-like
carbon properties.Comment: 18 pages, 10 figure
Numerical and experimental studies of the carbon etching in EUV-induced plasma
We have used a combination of numerical modeling and experiments to study
carbon etching in the presence of a hydrogen plasma. We model the evolution of
a low density EUV-induced plasma during and after the EUV pulse to obtain the
energy resolved ion fluxes from the plasma to the surface. By relating the
computed ion fluxes to the experimentally observed etching rate at various
pressures and ion energies, we show that at low pressure and energy, carbon
etching is due to chemical sputtering, while at high pressure and energy a
reactive ion etching process is likely to dominate
Interannual variability of the Black Sea Proper oxygen and nutrients regime: The role of climatic and anthropogenic forcing
The Black Sea is a unique, stratified, enclosed ocean basin of great importance. The water column provides a wealth of information concerning aerobic-anaerobic biogeochemistry, the responses of which can have links to anthropogenic and climatic forcing. Herein, we synthesize dissolved oxygen (DO) and nutrient data (phosphate, dissolved inorganic nitrogen (DIN), and silicate) for the period 1984-2010 received in the northeastern and western areas of the Sea. In the subsequent analysis we discuss the role of anthropogenic and climatic forcing in the context of the Black Sea oxic layer and oxic/anoxic interface characteristics.The DO concentration in the surface layer and in the Cold Intermediate Layer (CIL) decreased in warm periods and increased in cold periods, correlating to North Atlantic Oscillation (NAO) index variation. The biogeochemical regime of the Black Sea oxygenated upper layer has notably changed since 1999. After 1999 DO concentration in the CIL decreased by 20% while the concentrations in the surface layer changed very little. This provides evidence that the CIL waters were not fully replenished during the winters of the last decade.The nutrient concentrations (DIN and phosphate) in the surface layer decreased significantly in the 2000s compared with the 1980s-1990s. This decrease is regarded as improvement of the Black Sea ecosystem state. Oxygen and nutrient dynamics in the middle pycnocline have been decoupled since 1999. Presently physical (climatic) forcing is the dominant affecting factor controlling the Sea oxygen and nitrogen regime. © 2013 Elsevier Ltd
The heterogeneity of the properties of the coprolites <i>Aporrectodea caliginosa</i> and <i>Lumbricus rubellus</i> in model experiment with chernozem soil
The changes in the physical and microbiological properties of the coprolites of earthworms Aporrectodea caliginosa and Lumbricus rubellus were evaluated in laboratory experiments using the arable horizon of migratory-mycelial chernozem. In coprolites the following physical parameters were determined: particle size distribution, specific surface area, calculated by the effective particle diameter; microbiological parameters: the total number of cultured bacteria and the enzymatic kinetics of lipases according to the Michaelis –Menten model with the calculation of the maximum reaction rate (Vm) and Michaelis constant (Km). The model experiment included two stages: the first stage – earthworms of two species were kept together, in the second – separately. The control was the source soil and the soil with litter. Coprolites and the soil in which earthworms lived were analyzed and compared with the control. Two types of earthworms give a non-additive effect on physical and microbiological properties. Depending on the species composition, the nature of the change is different. For the two species contained together a decrease in the specific surface area in coprolites was noted, as well as an increase in the fraction of the fine sand due to the reduction of the fractions of silt, fine and medium dust. For A. caliginosa kept separately it was found, that the specific surface of coprolites increases compared to the control, the silt and fine, medium, coarse dust, fractions rise due to a significant reduction of the fine sand fraction. For L. rubellus coprolites a decrease in the specific surface area, an increase in the fractions of medium, fine sand and coarse dust, due to the reduction of silt, fine and medium dust fractions, are shown. The number of cultured heterotrophic bacteria is higher in coprolites compared to the control. The greatest increase is observed in the variant where two species are kept together. The lipase activity (Vm) of the soil also increases when two species are kept together compared with the control and with A. caliginosa kept separately. Under the influence of L. rubellus the lipase activity decreases. Coprolites differ in all the investigated properties from the control (soil and soil with litter), as well as from the soil where earthworms lived
The research program of the Liquid Scintillation Detector (LSD) in the Mont Blanc Laboratory
A massive (90 tons) liquid scintillation detector (LSD) has been running since October 1984 in the Mont Blanc Laboratory at a depth of 5,200 hg/sq cm of standard rock. The research program of the experiment covers a variety of topics in particle physics and astrophysics. The performance of the detector, the main fields of research are presented and the preliminary results are discussed
A photoluminescence study of excitonic grade CuInSe2 single crystals irradiated with 6 Mev electrons
High-quality single crystals of CuInSe2 with near-stoichiometric elemental compositions were irradiated with 6 MeV electrons, at doses from 1015 to 3 × 1018 cm−2, and studied using photoluminescence (PL) at temperatures from 4.2 to 300 K. Before irradiation, the photoluminescence spectra reveal a number of sharp and well resolved lines associated with free- and bound-excitons. The spectra also show broader bands relating to free-to-bound transitions and their phonon replicas in the lower energy region below 1.0 eV. The irradiation with 6 MeV electrons reduces the intensity of the free- and the majority of the bound-exciton peaks. Such a reduction can be seen for doses above 1016 cm−2. The irradiation induces new PL lines at 1.0215 eV and 0.9909 eV and also enhances the intensity of the lines at 1.0325 and 1.0102 eV present in the photoluminescence spectra before the irradiation. Two broad bands at 0.902 and 0.972 eV, respectively, are tentatively associated with two acceptor-type defects: namely, interstitial selenium (Sei) and copper on indium site (Cu In). After irradiation, these become more intense suggesting an increase in the concentration of these defects due to irradiation
On-line recognition of supernova neutrino bursts in the LVD detector
In this paper we show the capabilities of the Large Volume Detector (INFN
Gran Sasso National Laboratory) to identify a neutrino burst associated to a
supernova explosion, in the absence of an "external trigger", e.g., an optical
observation. We describe how the detector trigger and event selection have been
optimized for this purpose, and we detail the algorithm used for the on-line
burst recognition. The on-line sensitivity of the detector is defined and
discussed in terms of supernova distance and electron anti-neutrino intensity
at the source.Comment: Accepted for pubblication on Astroparticle Physics. 13 pages, 10
figure
First CNGS events detected by LVD
The CERN Neutrino to Gran Sasso (CNGS) project aims to produce a high energy,
wide band beam at CERN and send it toward the INFN Gran Sasso
National Laboratory (LNGS), 732 km away. Its main goal is the observation of
the appearance, through neutrino flavour oscillation. The beam
started its operation in August 2006 for about 12 days: a total amount of
protons were delivered to the target. The LVD detector, installed
in hall A of the LNGS and mainly dedicated to the study of supernova neutrinos,
was fully operating during the whole CNGS running time. A total number of 569
events were detected in coincidence with the beam spill time. This is in good
agreement with the expected number of events from Montecarlo simulations.Comment: Accepted for publication by the European Physical Journal C ; 7
pages, 11 figure
Study of the effect of neutrino oscillation on the supernova neutrino signal with the LVD detector
We present an update of our previous study (astro-ph/0112312) on how
oscillations affect the signal from a supernova core collapse observed in the
LVD detector at LNGS. In this paper we use a recent, more precise determination
of the cross section (astro-ph/0302055) to calculate the expected number of
inverse beta decay events, we introduce in the simulation also the -{\rm
Fe} interactions, we include the Earth matter effects and, finally, we study
also the inverted mass hierarchy case.Comment: 4 pages, 4 figures, to appear in the Proceedings of ICRC 200
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