24,292 research outputs found
Three-body decays: structure, decay mechanism and fragment properties
We discuss the three-body decay mechanisms of many-body resonances. R-matrix
sequential description is compared with full Faddeev computation. The role of
the angular momentum and boson symmetries is also studied. As an illustration
we show the computed -particle energy distribution after the decay of
12C(1^+) resonance at 12.7 MeV.Comment: 4 pages, 3 figures. Proceedings of the workshop "Critical Stability
of Few-Body Quantum Systems" 200
The Atmospheric Monitoring System of the JEM-EUSO Space Mission
An Atmospheric Monitoring System (AMS) is a mandatory and key device of a
space-based mission which aims to detect Ultra-High Energy Cosmic Rays (UHECR)
and Extremely-High Energy Cosmic Rays (EHECR) from Space. JEM-EUSO has a
dedicated atmospheric monitoring system that plays a fundamental role in our
understanding of the atmospheric conditions in the Field of View (FoV) of the
telescope. Our AMS consists of a very challenging space infrared camera and a
LIDAR device, that are being fully designed with space qualification to fulfil
the scientific requirements of this space mission. The AMS will provide
information of the cloud cover in the FoV of JEM-EUSO, as well as measurements
of the cloud top altitudes with an accuracy of 500 m and the optical depth
profile of the atmosphere transmittance in the direction of each air shower
with an accuracy of 0.15 degree and a resolution of 500 m. This will ensure
that the energy of the primary UHECR and the depth of maximum development of
the EAS ( Extensive Air Shower) are measured with an accuracy better than 30\%
primary energy and 120 depth of maximum development for EAS occurring
either in clear sky or with the EAS depth of maximum development above
optically thick cloud layers. Moreover a very novel radiometric retrieval
technique considering the LIDAR shots as calibration points, that seems to be
the most promising retrieval algorithm is under development to infer the Cloud
Top Height (CTH) of all kind of clouds, thick and thin clouds in the FoV of the
JEM-EUSO space telescope
Few-body decay and recombination in nuclear astrophysics
Three-body continuum problems are investigated for light nuclei of
astrophysical relevance. We focus on three-body decays of resonances or
recombination via resonances or the continuum background. The concepts of
widths, decay mechanisms and dynamic evolution are discussed. We also discuss
results for the triple decay in connection with resonances and
density and temperature dependence rates of recombination into light nuclei
from -particles and neutrons.Comment: 9 pages, 8 figures. Proceedings of the 21st European Few Body
Conference held in Salamanca (Spain) in August-September 201
Evidence of defect-induced ferromagnetism in ZnFeO thin films
X-ray absorption near-edge and grazing incidence X-ray fluorescence
spectroscopy are employed to investigate the electronic structure of
ZnFeO thin films. The spectroscopy techniques are used to determine
the non-equilibrium cation site occupancy as a function of depth and oxygen
pressure during deposition and its effects on the magnetic properties. It is
found that low deposition pressures below 10 mbar cause iron
superoccupation of tetrahedral sites without Zn inversion, resulting in
an ordered magnetic phase with high room temperature magnetic moment.Comment: Accepted for publication in Phys. Rev.
Maximum Entropy and Bayesian Data Analysis: Entropic Priors
The problem of assigning probability distributions which objectively reflect
the prior information available about experiments is one of the major stumbling
blocks in the use of Bayesian methods of data analysis. In this paper the
method of Maximum (relative) Entropy (ME) is used to translate the information
contained in the known form of the likelihood into a prior distribution for
Bayesian inference. The argument is inspired and guided by intuition gained
from the successful use of ME methods in statistical mechanics. For experiments
that cannot be repeated the resulting "entropic prior" is formally identical
with the Einstein fluctuation formula. For repeatable experiments, however, the
expected value of the entropy of the likelihood turns out to be relevant
information that must be included in the analysis. The important case of a
Gaussian likelihood is treated in detail.Comment: 23 pages, 2 figure
Analysis of self--averaging properties in the transport of particles through random media
We investigate self-averaging properties in the transport of particles
through random media. We show rigorously that in the subdiffusive anomalous
regime transport coefficients are not self--averaging quantities. These
quantities are exactly calculated in the case of directed random walks. In the
case of general symmetric random walks a perturbative analysis around the
Effective Medium Approximation (EMA) is performed.Comment: 4 pages, RevTeX , No figures, submitted to Physical Review E (Rapid
Communication
Limits on the Electromagnetic and Weak Dipole Moments of the Tau-Lepton in E_6 Superstring Models
We obtain limits on the electromagnetic and weak dipole moments of the
tau-lepton in the framework of a Left-Right symmetric model (LRSM) and a class
of inspired models with an additional neutral vector boson .
Using as an input the data obtained by the L3 and OPAL Collaborations for the
reaction , we get a stringent limit on the LRSM
mixing angle , , which in
turn induces bounds on the tau weak dipole moments which are consistent with
the bounds obtained recently by the DELPHI and ALEPH Collaborations from the
reaction . We also get similar bounds for the weak
dipole moments of the tau lepton in the framework of superstring models.Comment: 18 pages, 5 figure
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