3,775 research outputs found
Computational studies on the behaviour of anionic and nonionic surfactants at the SiO (silicon dioxide)/water interface
Molecular dynamics simulations to study the behaviour of anionic (Sodium
Dodecylsulfate, SDS) and nonionic (Monooleate of Sorbitan, SPAN80) surfactants
close to a SiO (silicon dioxide) surface were carried out. Simulations
showed that a water layer was first adsorbed on the surface and then the
surfactants were attached on that layer. Moreover, it was observed that water
behaviour close to the surface influenced the surfactant adsorption since a
semi-spherical micelle was formed on the SiO surface with SDS molecules
whereas a cylindrical micelle was formed with SPAN80 molecules. Adsorption of
the micelles was conducted in terms of structural properties (density profiles
and angular distributions) and dynamical behaviour (diffusion coefficients) of
the systems. Finally, it was also shown that some water molecules moved inside
the solid surface and located at specific sites of the solid surface.Comment: 8 pages, 6 fiigure
Geant4 based simulation of the Water Cherenkov Detectors of the LAGO Project
To characterize the signals registered by the different types of water
Cherenkov detectors (WCD) used by the Latin American Giant Observatory (LAGO)
Project, it is necessary to develop detailed simulations of the detector
response to the flux of secondary particles at the detector level. These
particles are originated during the interaction of cosmic rays with the
atmosphere. In this context, the LAGO project aims to study the high energy
component of gamma rays bursts (GRBs) and space weather phenomena by looking
for the solar modulation of galactic cosmic rays (GCRs). Focus in this, a
complete and complex chain of simulations is being developed that account for
geomagnetic effects, atmospheric reaction and detector response at each LAGO
site. In this work we shown the first steps of a GEANT4 based simulation for
the LAGO WCD, with emphasis on the induced effects of the detector internal
diffusive coating.Comment: 5 pages, 4 figures, Proceedings X SILAFAE Medellin-2014. To appear in
Nuclear Physics B - Proceedings Supplement
Cosmic Rays Induced Background Radiation on Board of Commercial Flights
The aim of this work is to determine the total integrated flux of cosmic
radiation which a commercial aircraft is exposed to along specific flight
trajectories. To study the radiation background during a flight and its
modulation by effects such as altitude, latitude, exposure time and transient
magnetospheric events, we perform simulations based on Magnetocosmics and
CORSIKA codes, the former designed to calculate the geomagnetic effects on
cosmic rays propagation and the latter allows us to simulate the development of
extended air showers in the atmosphere. In this first work, by considering the
total flux of cosmic rays from 5 GeV to 1 PeV, we obtained the expected
integrated flux of secondary particles on board of a commercial airplane during
the Bogot\'a-Buenos Aires trip by point-to-point numerical integration.Comment: 5 pages, 2 figures, Proceedings X SILAFAE Medellin-2014. To appear in
Nuclear Physics B - Proceedings Supplement
Implementing the De-thinning Method for High Energy Cosmic Rays Extensive Air Shower Simulations
To simulate the interaction of cosmic rays with the Earth atmosphere requires
highly complex computational resources and several statistical techniques have
been developed to simplify those calculations. It is common to implement the
thinning algorithms to reduce the number of secondary particles by assigning
weights to representative particles in the evolution of the cascade. However,
since this is a compression method with information loss, it is required to
recover the original flux of secondary particles without introduce artificial
biases. In this work we present the preliminary results of our version of the
de-thinning algorithm for the reconstruction of thinned simulations of
extensive air showers initiated by cosmic rays and photons in the energy range
.Comment: 5 pages, 2 figures, 1 table, Proceedings X SILAFAE Medellin-2014. To
appear in Nuclear Physics B - Proceedings Supplement
Plausible families of compact objects with a Non Local Equation of State
We investigate the plausibility of some models emerging from an algorithm
devised to generate a one-parameter family of interior solutions for the
Einstein equations. It is explored how their physical variables change as the
family-parameter varies. The models studied correspond to anisotropic spherical
matter configurations having a non local equation of state. This particular
type of equation of state with no causality problems provides, at a given
point, the radial pressure not only as a function of the density but as a
functional of the enclosed matter distribution. We have found that there are
several model-independent tendencies as the parameter increases: the equation
of state tends to be stiffer and the total mass becomes half of its external
radius. Profiting from the concept of cracking of materials in General
Relativity, we obtain that those models become more stable as the family
parameter increases
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