321 research outputs found
Luminosity Measurement at COMPASS
The measurement of absolutely normalized cross sections for high-energy
scattering processes is an important reference for theoretical models. This
paper discusses the first determination of the luminosity for data of the
COMPASS experiment, which is the basis for such measurements. The resulting
normalization is validated via the determination of the structure function
from COMPASS data, which is compared to literature.Comment: Invited contribution to the conference on Symmetries and Spin
SPIN-Praha-2010, to be published in European Physical Journal Special Topic
A Novel Generic Framework for Track Fitting in Complex Detector Systems
This paper presents a novel framework for track fitting which is usable in a
wide range of experiments, independent of the specific event topology, detector
setup, or magnetic field arrangement. This goal is achieved through a
completely modular design. Fitting algorithms are implemented as
interchangeable modules. At present, the framework contains a validated Kalman
filter. Track parameterizations and the routines required to extrapolate the
track parameters and their covariance matrices through the experiment are also
implemented as interchangeable modules. Different track parameterizations and
extrapolation routines can be used simultaneously for fitting of the same
physical track. Representations of detector hits are the third modular
ingredient to the framework. The hit dimensionality and orientation of planar
tracking detectors are not restricted. Tracking information from detectors
which do not measure the passage of particles in a fixed physical detector
plane, e.g. drift chambers or TPCs, is used without any simplifications. The
concept is implemented in a light-weight C++ library called GENFIT, which is
available as free software
Spontaneous symmetry breaking as a resource for noncritically squeezed light
In the last years we have proposed the use of the mechanism of spontaneous
symmetry breaking with the purpose of generating perfect quadrature squeezing.
Here we review previous work dealing with spatial (translational and
rotational) symmetries, both on optical parametric oscillators and four-wave
mixing cavities, as well as present new results. We then extend the phenomenon
to the polarization state of the signal field, hence introducing spontaneous
polarization symmetry breaking. Finally we propose a Jaynes-Cummings model in
which the phenomenon can be investigated at the single-photon-pair level in a
non-dissipative case, with the purpose of understanding it from a most
fundamental point of view.Comment: Review for the proceedings of SPIE Photonics Europe. 11 pages, 5
figures
Autonomous clustering using rough set theory
This paper proposes a clustering technique that minimises the need for subjective
human intervention and is based on elements of rough set theory. The proposed algorithm is
unified in its approach to clustering and makes use of both local and global data properties to
obtain clustering solutions. It handles single-type and mixed attribute data sets with ease and
results from three data sets of single and mixed attribute types are used to illustrate the
technique and establish its efficiency
Propagation of High-Energy Cosmic Rays through the Galaxy: Discussion and In- terpretation of TRACER Results
Abstract: The long-duration balloon flights of TRACER provide new measurements of the intensities and energy spectra of the arriving cosmic-ray nuclei with 5 ≤ Z ≤ 26 at high energies. In order to determine the particle composition and energy spectra at the cosmic-ray sources, changes occurring during the interstellar propagation of cosmic rays must be known. We use a simple propagation model with energydependent pathlength and derive constraints on the propagation parameters from a self-consistent fit to the measured energy spectra. We use the model to obtain the relative abundances of the cosmic ray nuclei at the acceleration site
The PANDA GEM-based TPC Prototype
We report on the development of a GEM-based TPC prototype for the PANDA
experiment. The design and requirements of this device will be illustrated,
with particular emphasis on the properties of the recently tested GEM-detector,
the characterization of the read-out electronics and the development of the
tracking software that allows to evaluate the GEM-TPC data.Comment: submitted to NIMA 4 pages, 6 picture
Cosmic Ray Energy Spectra of Primary Nuclei from Oxygen to Iron: Results from the TRACER 2003 LDB Flight
Abstract: The first long-duration balloon flight of TRACER in 2003 provided high-quality measurements of the primary cosmic-ray nuclei over the range oxygen (Z = 8) to iron (Z = 26). The analysis of these measurements is now complete, and we will present the individual energy spectra and absolute intensities of the nuclei O, Ne, Mg, Si, S, Ca, Ar, and Fe. The spectra cover the energy range from 1 GeV/nucleon to more than 10 TeV/nucleon, or in terms of total energy, to several 10 14 eV per particle. We compare our results with those of other recent observations in space and on balloons and notice, in general, good agreement with these data for those regions where overlap exists. We also compare our data with information that has recently been inferred from air shower observations
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