550 research outputs found
Morphological and functional effects of graphene on the synthesis of uranium carbide for isotopes production targets
Novel Scintillating Materials Based on Phenyl-Polysiloxane for Neutron Detection and Monitoring
Neutron detectors are extensively used at many nuclear research facilities
across Europe. Their application range covers many topics in basic and applied
nuclear research: in nuclear structure and reaction dynamics (reaction
reconstruction and decay studies); in nuclear astrophysics (neutron emission
probabilities); in nuclear technology (nuclear data measurements and
in-core/off-core monitors); in nuclear medicine (radiation monitors,
dosimeters); in materials science (neutron imaging techniques); in homeland
security applications (fissile materials investigation and cargo inspection).
Liquid scintillators, widely used at present, have however some drawbacks given
by toxicity, flammability, volatility and sensitivity to oxygen that limit
their duration and quality. Even plastic scintillators are not satisfactory
because they have low radiation hardness and low thermal stability. Moreover
organic solvents may affect their optical properties due to crazing. In order
to overcome these problems, phenyl-polysiloxane based scintillators have been
recently developed at Legnaro National Laboratory. This new solution showed
very good chemical and thermal stability and high radiation hardness. The
results on the different samples performance will be presented, paying special
attention to a characterization comparison between synthesized phenyl
containing polysiloxane resins where a Pt catalyst has been used and a
scintillating material obtained by condensation reaction, where tin based
compounds are used as catalysts. Different structural arrangements as a result
of different substituents on the main chain have been investigated by High
Resolution X-Ray Diffraction, while the effect of improved optical
transmittance on the scintillation yield has been elucidated by a combination
of excitation/fluorescence measurements and scintillation yield under exposure
to alpha and {\gamma}-rays.Comment: InterM 2013 - International Multidisciplinary Microscopy Congres
Use of WWI photos for quantitative reconstructions of glaciers along the Italian-Austrian front
Cytotoxic activity of gemcitabine, alone or in combination with mitotane, in adrenocortical carcinoma cell lines.
High-Resolution monitoring of current rapid transformations on glacial and periglacial environments
Glacial and periglacial environments are highly sensitive to climatic changes. Processes of cryosphere degradation may strongly impact human activities and infrastructures, and need to be monitored for improved understanding and for mitigation/adaptation. Studying glacial and periglacial environments using traditional techniques may be difficult or not feasible, but new remote sensing techniques like terrestrial and aerial laser scanner opened new possibilities for cryospheric studies. This work presents an application of the terrestrial laser scanner (TLS) for monitoring the current rapid changes occurring on the Montasio Occidentale glacier (Eastern Italian alps), which is representative of low-altitude, avalanche-fed and debris-cover glaciers. These glaciers are quite common in the Alps but their reaction to climate changes is still poorly known. The mass balance, surface velocity fields, debris cover dynamics and effects of meteorological extremes were investigated by repeat high-resolution TLS scanning from September 2010 to October 2012. The results were encouraging and shed light on the peculiar response of this glacier to climatic changes, on its current dynamics and on the feedback played by the debris cover, which is critical for its preservation. The rapid transformations in act, combined with the unstable ice mass, large amount of loose debris and channeled runoff during intense rainfalls, constitute a potential area for the formation of large debris flows, as shown by field evidences and documented by the recent literature
ZnS (Mn) Nanoparticles as Luminescent Centers for Siloxane Based Scintillators
Synthesis of oleic acid stabilized ZnS nanocrystals activated with Mn is pursued. A hydrothermal method where high pressure and temperature are applied to control the nanocrystals growth is adopted. Capping the nanoparticle surface with oleic acid (OA) improved light output. Samples loaded with both the phosphor and the neutron sensitizer have been produced and tested in a preliminary test as alpha particle detectors and secondly as thermal neutron detectors. The results support further development for siloxane-based scintillator detectors employing ZnS (Mn) nanoparticles
Role of Modified Chaplygin Gas as a Dark Energy Model in Collapsing Spherically Symmetric Cloud
In this work, gravitational collapse of a spherical cloud, consists of both
dark matter and dark energy in the form of modified Chaplygin gas is studied.
It is found that dark energy alone in the form of modified Chaplygin gas forms
black hole. Also when both components of the fluid are present then the
collapse favors the formation of black hole in cases the dark energy dominates
over dark matter. The conclusion is totally opposite to the usually known
results.Comment: 7 Latex Pages, RexTex style, No figure
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