3,097 research outputs found
A survey of particle contamination in electronic devices
The experiences are given of a number of National Aeronautics and Space Administration (NASA) and Space and Missile System Organization (SAMSO) contractors with particle contamination, and the methods used for its prevention and detection, evaluates the bases for the different schemes, assesses their effectiveness, and identifies the problems associated with each. It recommends specific short-range tests or approaches appropriate to individual part-type categories and recommends that specific tasks be initiated to refine techniques and to resolve technical and application facets of promising solutions
Upgrade of the SPS extraction Kickers for LHC and CNGS Operation
The extraction kickers of the Super Proton Synchrotron (SPS) need to be upgraded to meet the Large Hadron Collider (LHC) and CERN Neutrino to Grand Sasso (CNGS) requirements. Commissioning of the extraction towards one of the LHC rings and the CNGS facility under construction is foreseen for 2003. The ferrites of the kicker magnets will be heated significantly by the circulating beam and need to be cooled to stay below the Curie temperature. A cost-effective solution to this problem is presented consisting of AlN water cooled plates on the top and bottom of the ferrites. Model predictions are compared with preliminary laboratory measurements and machine data from the SPS. Commissioning of the extraction towards the other LHC ring is planned for 2006. Beyond the heat load issues, this latter extraction needs a larger horizontal "kick" and thus a higher magnetic field and larger horizontal beam aperture. The rise and fall time requirements of these kickers are less strict, therefore a new system with lower impedance permitting a larger magnetic field can be used
Test of Chemical freeze-out at RHIC
We present the results of a systematic test applying statistical thermal
model fits in a consistent way for different particle ratios, and different
system sizes using the various particle yields measured in the STAR experiment.
Comparison between central and peripheral Au+Au and Cu+Cu collisions with data
from p+p collisions provides an interesting tool to verify the dependence with
the system size. We also present a study of the rapidity dependence of the
thermal fit parameters using available data from RHIC in the forward rapidity
regions and also using different parameterization for the rapidity distribution
of different particles.Comment: SQM2008 conference proceeding
System Size Dependence of Particle Production at the SPS
Recent results on the system size dependence of net-baryon and hyperon
production as measured at the CERN SPS are discussed. The observed Npart
dependences of yields, but also of dynamical properties, such as average
transverse momenta, can be described in the context of the core corona
approach. Other observables, such as antiproton yields and net-protons at
forward rapidities, do not follow the predictions of this model. Possible
implications for a search for a critical point in the QCD phase diagram are
discussed. Event-by-event fluctuations of the relative core to corona source
contributions might influence fluctuation observables (e.g. multiplicity
fluctuations). The magnitude of this effect is investigated.Comment: 10 pages, 4 figurs. Proceedings of the 6th International Workshop on
Critical Point and Onset of Deconfinement in Dubna, Aug. 201
Strange Particle Production at RHIC
We report STAR measurements of mid-rapidity yields for the ,
, , , , , and
particles in Cu+Cu and Au+Au GeV
collisions. We show that at a given number of participating nucleons, bulk
strangeness production is higher in Cu+Cu collisions compared to Au+Au
collisions at the same center of mass energy, counter to predictions from the
Canonical formalism. We compare both the Cu+Cu and Au+Au yields to AMPT and
EPOS predictions, and find they reproduce key qualitative aspects of the data.
Finally, we investigate other scaling parameters and find bulk strangeness
production for both the measured data and theoretical predictions, scales
better with the number participants that undergo more than one collision.Comment: Conference proceedings for Hot Quarks 2008, 5 pages and 4 figure
Overview of Strangeness Production at the STAR Experiment
We present an overview of recent STAR results on strangeness production in
p+p and heavy-ion collisions at RHIC. In both Cu+Cu and Au+Au collisions we
show the centrality dependencies of bulk yield and mid- spectrum
measurements with new comparisons to theory. The latest results for
strange particles are presented and prospects for strangeness production in the
low energy scan program will be outlined. Finally, we report new measurements
of strangeness fragmentation functions for jets in p+p collisions.Comment: 8 pages, 7 figures, proceedings for SQM 200
Fluctuation and flow probes of early-time correlations in relativistic heavy ion collisions
Fluctuation and correlation observables are often measured using
multi-particle correlation methods and therefore mutually probe the origins of
genuine correlations present in multi-particle distribution functions. We
investigate the common influence of correlations arising from the spatially
inhomogeneous initial state on multiplicity and momentum fluctuations as well
as flow fluctuations. Although these observables reflect different aspects of
the initial state, taken together, they can constrain a correlation scale set
at the earliest moments of the collision. We calculate both the correlation
scale in an initial stage Glasma flux tube picture and the modification to
these correlations from later stage hydrodynamic flow and find quantitative
agreement with experimental measurements over a range of collision systems and
energies.Comment: Proceedings of the 28th Winter Workshop on Nuclear Dynamics, Dorado
del Mar, Puerto Rico, April 7-14, 201
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Liquid membrane system for the removal and concentration of transuranic elements
The goal of this program is to develop an efficient, reliable, and radiation-resistant modified liquid membrane system (MLMS) for the selective removal and concentration of transuranic elements (TRUs) and strontium-90 from dissolved Hanford sludge wastes. The efforts are divided into three categories: (1) demonstration and optimization of the MLMS for the TRUEX and SREX processes using simulant waste solution; (2) development of a radiation-resistant microporous divider and membrane module for testing with actual waste solutions; and (3) demonstration of the MLMS for the TRUEX and SREX processes using actual Hanford waste. Successful completion of these development efforts will yield a compact, versatile, and reliable MLMS for implementation with the TRUEX and SREX processes. The MLMS is simple, stable, more efficient, and easier to control and operate than conventional solvent-extraction processes, such as those employing centrifugal contactors. In addition, the MLMS process offers operational cost savings over the conventional technology, by exhibiting at least a 10% reduction in the consumption of extractant chemicals
Jet reconstruction and underlying event studies in p+p and d+Au collisions from STAR
Description of parton interaction with the hot and dense nuclear matter
created in heavy-ion collisions at high energies is a complex task, which
requires a detailed knowledge of jet production in p+p and d+Au collisions.
Measurements in these collision systems are therefore essential to disentangle
initial state nuclear effects from cold nuclear matter effects, medium-induced
broadening and jet quenching. To obtain complete description of the p+p
(d+Au) collision it is also important to study particle production in the
underlying event. The measured properties of underlying event can be used to
tune the QCD based Monte-Carlo models.
In this paper some of the recent results on jet and underlying event
properties in p+p and d+Au collisions at = 200 GeV measured by
the STAR experiment are presented. In particular, the preliminary results on
charged and strange particle fragmentation functions in p+p collisions are
discussed and confronted with PYTHIA simulations. Next, the measurement of
inclusive jet spectrum and di-jet correlations in d+Au collisions is presented
and compared with the measurements in p+p collisions to estimate the size of
cold nuclear matter effects. Finally, the study of underlying event properties
in p+p collisions is shown and compared to PYTHIA simulation.Comment: 9 pages, 8 figures, proceedings of the 27th Winter Workshop on
Nuclear Dynamics, Winter Park, Colorado, US
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