508 research outputs found
Online Pattern Recognition for the ALICE High Level Trigger
The ALICE High Level Trigger has to process data online, in order to select
interesting (sub)events, or to compress data efficiently by modeling
techniques.Focusing on the main data source, the Time Projection Chamber (TPC),
we present two pattern recognition methods under investigation: a sequential
approach "cluster finder" and "track follower") and an iterative approach
("track candidate finder" and "cluster deconvoluter"). We show, that the former
is suited for pp and low multiplicity PbPb collisions, whereas the latter might
be applicable for high multiplicity PbPb collisions, if it turns out, that more
than 8000 charged particles would have to be reconstructed inside the TPC.
Based on the developed tracking schemes we show, that using modeling techniques
a compression factor of around 10 might be achievableComment: Realtime Conference 2003, Montreal, Canada to be published in IEEE
Transactions on Nuclear Science (TNS), 6 pages, 8 figure
Development of Wireless Techniques in Data and Power Transmission - Application for Particle Physics Detectors
Wireless techniques have developed extremely fast over the last decade and
using them for data and power transmission in particle physics detectors is not
science- fiction any more. During the last years several research groups have
independently thought of making it a reality. Wireless techniques became a
mature field for research and new developments might have impact on future
particle physics experiments. The Instrumentation Frontier was set up as a part
of the SnowMass 2013 Community Summer Study [1] to examine the instrumentation
R&D for the particle physics research over the coming decades: {\guillemotleft}
To succeed we need to make technical and scientific innovation a priority in
the field {\guillemotright}. Wireless data transmission was identified as one
of the innovations that could revolutionize the transmission of data out of the
detector. Power delivery was another challenge mentioned in the same report. We
propose a collaboration to identify the specific needs of different projects
that might benefit from wireless techniques. The objective is to provide a
common platform for research and development in order to optimize effectiveness
and cost, with the aim of designing and testing wireless demonstrators for
large instrumentation systems
Recent results on strangeness production from NA49
We present a summary of measurements of strange particles performed by the
experiment NA49 in inelastic p+p interactions, as well as semi-central C+C and
Si+Si, central Pb+Pb, and minimum bias Pb+Pb collisions in the energy range
= 6.3 - 17.3 GeV. New results on , and
production in minimum bias Pb+Pb collisions at = 8.7 and 17.3
are shown. Furthermore the strangeness enhancement factor at =
17.3 GeV is presented and compared to the results from NA57 and STAR. Energy
dependence of strange particle yields normalized to pion yields is presented.
New data on production are shown at = 17.3
GeV. Furthermore we present the energy dependence of and
fluctuations. The data are compared with model predictions.Comment: 9 pages, 7 figures, Submitted to J. Phys. G (Proceedings of the
International Conference on Strangeness in Quark Matter, Buzios, Rio de
Janeiro, Brazil, September 27 - October 2, 2009
Source Dimensions in Ultrarelativistic Heavy Ion Collisions
Recent experiments on pion correlations, interpreted as interferometric
measurements of the collision zone, are compared with models that distinguish a
prehadronic phase and a hadronic phase. The models include prehadronic
longitudinal expansion, conversion to hadrons in local kinetic equilibrium, and
rescattering of the produced hadrons. We find that the longitudinal and outward
radii are surprisingly sensitive to the algorithm used for two-body collisions.
The longitudinal radius measured in collisions of 200 GeV/u sulfur nuclei on a
heavy target requires the existence of a prehadronic phase which converts to
the hadronic phase at densities around 0.8-1.0 GeV/fm. The transverse radii
cannot be reproduced without introducing more complex dynamics into the
transverse expansion.Comment: RevTeX 3.0, 28 pages, 6 figures, not included, revised version, major
change is an additional discussion of the classical two-body collision
algorithm, a (compressed) postscript file of the complete paper including
figures can be obtained from Authors or via anonymous ftp at
ftp://ftp_int.phys.washington.edu/pub/herrmann/pisource.ps.
Over 65% sunlight absorption in a 1 mu m Si slab with hyperuniform texture
Thin, flexible, and invisible solar cells will be a ubiquitous technology in the near future. Ultrathin crystalline silicon (c-Si) cells capitalize on the success of bulk silicon cells while being lightweight and mechanically flexible, but suffer from poor absorption and efficiency. Here we present a new family of surface texturing, based on correlated disordered hyperuniform patterns, capable of efficiently coupling the incident spectrum into the silicon slab optical modes. We experimentally demonstrate 66.5% solar light absorption in free-standing 1 μm c-Si layers by hyperuniform nanostructuring for the spectral range of 400 to 1050 nm. The absorption equivalent photocurrent derived from our measurements is 26.3 mA/cm2, which is far above the highest found in literature for Si of similar thickness. Considering state-of-the-art Si PV technologies, we estimate that the enhanced light trapping can result in a cell efficiency above 15%. The light absorption can potentially be increased up to 33.8 mA/cm2 by incorporating a back-reflector and improved antireflection, for which we estimate a photovoltaic efficiency above 21% for 1 μm thick Si cells
Signatures of Quark-Gluon-Plasma formation in high energy heavy-ion collisions: A critical review
A critical review on signatures of Quark-Gluon-Plasma formation is given and
the current (1998) experimental status is discussed. After giving an
introduction to the properties of QCD matter in both, equilibrium- and
non-equilibrium theories, we focus on observables which may yield experimental
evidence for QGP formation. For each individual observable the discussion is
divided into three sections: first the connection between the respective
observable and QGP formation in terms of the underlying theoretical concepts is
given, then the relevant experimental results are reviewed and finally the
current status concerning the interpretation of both, theory and experiment, is
discussed. A comprehensive summary including an outlook towards RHIC is given
in the final section.Comment: Topical review, submitted to Journal of Physics G: 68 pages,
including 39 figures (revised version: only minor modifications, some
references added
NA61/SHINE facility at the CERN SPS: beams and detector system
NA61/SHINE (SPS Heavy Ion and Neutrino Experiment) is a multi-purpose
experimental facility to study hadron production in hadron-proton,
hadron-nucleus and nucleus-nucleus collisions at the CERN Super Proton
Synchrotron. It recorded the first physics data with hadron beams in 2009 and
with ion beams (secondary 7Be beams) in 2011.
NA61/SHINE has greatly profited from the long development of the CERN proton
and ion sources and the accelerator chain as well as the H2 beamline of the
CERN North Area. The latter has recently been modified to also serve as a
fragment separator as needed to produce the Be beams for NA61/SHINE. Numerous
components of the NA61/SHINE set-up were inherited from its predecessors, in
particular, the last one, the NA49 experiment. Important new detectors and
upgrades of the legacy equipment were introduced by the NA61/SHINE
Collaboration.
This paper describes the state of the NA61/SHINE facility - the beams and the
detector system - before the CERN Long Shutdown I, which started in March 2013
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