15,221 research outputs found
Early Results on Radioactive Background Characterization for Sanford Laboratory and DUSEL Experiments
Measuring external sources of background for a deep underground laboratory at
the Homestake Mine is an important step for the planned low-background
experiments. The naturally occurring -ray fluxes at different levels in
the Homestake Mine are studied using NaI detectors and Monte Carlo simulations.
A simple algorithm is developed to convert the measured -ray rates into
-ray fluxes. A good agreement between the measured and simulated
-ray fluxes is achieved with the knowledge of the chemical composition
and radioactivity levels in the rock. The neutron fluxes and -ray
fluxes are predicted by Monte Carlo simulations for different levels including
inaccessible levels that are under construction for the planned low background
experiments.Comment: 16 pages, 2 figures, and 9 table
Simple one-dimensional quantum-mechanical model for a particle attached to a surface
We present a simple one-dimensional quantum-mechanical model for a particle
attached to a surface. We solve the Schr\"odinger equation in terms of Weber
functions and discuss the behavior of the eigenvalues and eigenfunctions. We
derive the virial theorem and other exact relationships as well as the
asymptotic behaviour of the eigenvalues. We calculate the zero-point energy for
model parameters corresponding to H adsorbed on Pd(100) and also outline the
application of the Rayleigh-Ritz variational method
Rotational Perturbations of Friedmann-Robertson-Walker Type Brane-World Cosmological Models
First order rotational perturbations of the Friedmann-Robertson-Walker metric
are considered in the framework of the brane-world cosmological models. A
rotation equation, relating the perturbations of the metric tensor to the
angular velocity of the matter on the brane is derived under the assumption of
slow rotation. The mathematical structure of the rotation equation imposes
strong restrictions on the temporal and spatial dependence of the brane matter
angular velocity. The study of the integrable cases of the rotation equation
leads to three distinct models, which are considered in detail. As a general
result we find that, similarly to the general relativistic case, the rotational
perturbations decay due to the expansion of the matter on the brane. One of the
obtained consistency conditions leads to a particular, purely inflationary
brane-world cosmological model, with the cosmological fluid obeying a
non-linear barotropic equation of state.Comment: 14 pages, 5 figures, REVTEX
Peningkatan Kualitas Pembelajaran Tematik Melalui Model Pembelajaran Aktif Tipe Index Card Match
Stage of development of the child in accordance with the characteristics of how children learn, the learning process is the most appropriate thematic learning. Thematic is tepadu learning by using themes to associate some subjects so as to provide a meaningful experience to the students. Based on initial observations in class II Banyutowo Kendal SDN 2 shows the results of student learning is not maximized, because the teachers have not been using a variety of methods, inadequate instructional media, student activities passive and apathetic. Achievement of classical completeness for the Civics subjects and 37.5% for subjects Indonesian namely 45.8%. This research is a classroom action research (CAR). In this PTK is the subject of the study is the second grade students of SDN Banyutowo Kendal, amounting to 24 students. The study was planned in the second semester of academic year 2012/2013. By using about as much as 20 points to the data analysis used descriptive analysis includes determining the completeness of individual and classical. Results of this study showed improvement of teacher skills, student activities, and student learning outcomes in thematic learning through active learning model type Index Card Match. Average student activity increased less than 47% category (first cycle), a good 75% category (cycle II). The average teacher\u27s skills increased from 47% category of very less (first cycle), a good 72% category (cycle II). Average student learning outcomes increased from an average value of 58.75 with classical completeness 37.5% lower category (first cycle), has increased the average value is 78.75 with classical completeness of 83.3% is very high category (cycle II). Based on the results of this study concluded that the active learning model Index Card Match type proven to improve the quality of thematic learning indicated on improving the skills of teachers, student activities and student learning outcomes. Suggestions should be submitted to teachers seeking to improve the quality of learning in the classroom by applying active learning model Index Card Match type which can improve the skills of teachers, student activities, and student learning outcomes
Logarithmic correction in the deformed model to produce the heavy quark potential and QCD beta function
We stude the \textit{holographic} QCD model which contains a quadratic term and a logarithmic term with an
explicit infrared cut-off in the deformed warp factor.
We investigate the heavy quark potential for three cases, i.e, with only
quadratic correction, with both quadratic and logarithmic corrections and with
only logarithmic correction. We solve the dilaton field and dilation potential
from the Einstein equation, and investigate the corresponding beta function in
the G{\"u}rsoy -Kiritsis-Nitti (GKN) framework. Our studies show that in the
case with only quadratic correction, a negative or the
Andreev-Zakharov model is favored to fit the heavy quark potential and to
produce the QCD beta-function at 2-loop level, however, the dilaton potential
is unbounded in infrared regime. One interesting observing for the case of
positive , or the soft-wall model is that the
corresponding beta-function exists an infrared fixed point. In the case with
only logarithmic correction, the heavy quark Cornell potential can be fitted
very well, the corresponding beta-function agrees with the QCD beta-function at
2-loop level reasonably well, and the dilaton potential is bounded from below
in infrared. At the end, we propose a more compact model which has only
logarithmic correction in the deformed warp factor and has less free
parameters.Comment: 24 pages, 16 figure
- …