6,467 research outputs found
Measurement of prompt (2S) to J/ yield ratios in Pb-Pb and p-p collisions at = 2.76 TeV
The ratio between the prompt ψ(2S) and J/ψ yields, reconstructed via their decays into μ+μ-, is measured in Pb-Pb and p-p collisions at sNN=2.76  TeV. The analysis is based on Pb-Pb and p-p data samples collected by CMS at the Large Hadron Collider, corresponding to integrated luminosities of 150  μb-1 and 5.4  pb-1, respectively. The double ratio of measured yields (Nψ(2S)/NJ/ψ)Pb-Pb/(Nψ(2S)/NJ/ψ)p-p is computed in three Pb-Pb collision centrality bins and two kinematic ranges: one at midrapidity, |y|<1.6, covering the transverse momentum range 6.5<pT<30  GeV/c, and the other at forward rapidity, 1.6<|y|<2.4, extending to lower pT values, 3<pT<30  GeV/c. The centrality-integrated double ratio changes from 0.45±0.13(stat)±0.07(syst) in the first range to 1.67±0.34(stat)±0.27(syst) in the second. This difference is most pronounced in the most central collisions
Bone-Anchored Hearing Aids Fitted According to NAL and DSL Procedures in Adults with Mixed Hearing Loss
BACKGROUND: Bone-anchored hearing aids represent a valid alternative for patients with conductive/mixed hearing loss who cannot use hearing aids. To date, these devices have given good audiological results, thanks to various fitting prescription programs (i.e., National Acoustic Laboratories and Desired Sensation Level). The aim of this study is to compare 2 types of fitting algorithms (National Acoustic Laboratories and Desired Sensation Level) implemented for bone-anchored hearing devices. METHODS: We retrospectively enrolled 10 patients followed at our operative unit, suffering from bilateral symmetrical mixed hearing loss and who underwent bone-anchored hearing aid implantation. All patients experienced each prescriptive procedure, National Acoustic Laboratories and Desired Sensation Level, for 7 months (on average), and they were subjected to audiological tests and questionnaires to evaluate the best program. RESULTS: National Acoustic Laboratories and Desired Sensation Level prescriptions yielded similar results. Desired Sensation Level allowed less amplification of the low frequencies than the National Acoustic Laboratories prescription, and these differences were the only statistically significant. Desired Sensation Level allowed better disyllabic word and sentence recognition scores only in quiet and not in noisy conditions. The subjective questionnaires showed similar results. At the end of the trial sessions, more patients (60%) definitively chose the Desired Sensation Level program for their device. These patients were those with a worse hearing threshold. CONCLUSION: The 2 prescriptive programs allowed similar results although patients with a worse threshold seem to prefer the DSL program. This is the first evaluation of the 2 prescriptive programs, National Acoustic Laboratories versus Desired Sensation Level, for bone conduction devices available in the literature. Further studies are needed to confirm this initial finding
Development of FTK architecture: a fast hardware track trigger for the ATLAS detector
The Fast Tracker (FTK) is a proposed upgrade to the ATLAS trigger system that
will operate at full Level-1 output rates and provide high quality tracks
reconstructed over the entire detector by the start of processing in Level-2.
FTK solves the combinatorial challenge inherent to tracking by exploiting the
massive parallelism of Associative Memories (AM) that can compare inner
detector hits to millions of pre-calculated patterns simultaneously. The
tracking problem within matched patterns is further simplified by using
pre-computed linearized fitting constants and leveraging fast DSP's in modern
commercial FPGA's. Overall, FTK is able to compute the helix parameters for all
tracks in an event and apply quality cuts in approximately one millisecond. By
employing a pipelined architecture, FTK is able to continuously operate at
Level-1 rates without deadtime. The system design is defined and studied using
ATLAS full simulation. Reconstruction quality is evaluated for single muon
events with zero pileup, as well as WH events at the LHC design luminosity. FTK
results are compared with the tracking capability of an offline algorithm.Comment: To be published in the proceedings of DPF-2009, Detroit, MI, July
2009, eConf C09072
The Evolution of FTK, a Real-Time Tracker for Hadron Collider Experiments
We describe the architecture evolution of the highly-parallel dedicated
processor FTK, which is driven by the simulation of LHC events at high
luminosity (1034 cm-2 s-1). FTK is able to provide precise on-line track
reconstruction for future hadronic collider experiments. The processor,
organized in a two-tiered pipelined architecture, execute very fast algorithms
based on the use of a large bank of pre-stored patterns of trajectory points
(first tier) in combination with full resolution track fitting to refine
pattern recognition and to determine off-line quality track parameters. We
describe here how the high luminosity simulation results have produced a new
organization of the hardware inside the FTK processor core.Comment: 11th ICATPP conferenc
Characterization of irradiated RD53A pixel modules with passive CMOS sensors
We are investigating the feasibility of using CMOS foundries to fabricate
silicon detectors, both for pixels and for large-area strip sensors. The
availability of multi-layer routing will provide the freedom to optimize the
sensor geometry and the performance, with biasing structures in poly-silicon
layers and MIM-capacitors allowing for AC coupling. A prototyping production of
strip test-structures and RD53A compatible pixel sensors was recently completed
at LFoundry in a 150nm CMOS process. This paper will focus on the
characterization of irradiated and non-irradiated pixel modules, composed by a
CMOS passive sensor interconnected to a RD53A chip. The sensors are designed
with a pixel cell of in case of DC coupled
devices and for the AC coupled ones. Their
performance in terms of charge collection, position resolution, and hit
efficiency was studied with measurements performed in the laboratory and with
beam tests. The RD53A modules with LFoundry silicon sensors were irradiated to
fluences up to
Measurement of the inclusive leptonic asymmetry in top-quark pairs that decay to two charged leptons at CDF
We measure the inclusive forward-backward asymmetry of the charged-lepton pseudorapidities from top-quark pairs produced in proton-antiproton collisions, and decaying to final states that contain two charged leptons (electrons or muons), using data collected with the Collider Detector at Fermilab. With an integrated luminosity of 9.1 , the leptonic forward-backward asymmetry, , is measured to be and the leptonic pair forward-backward asymmetry, , is measured to be , compared with the standard model predictions of and , respectively. Additionally, we combine the result with a previous determination from a final state with a single lepton and hadronic jets and obtain
Present Limits on the Precision of SM Predictions for Jet Energies
We investigate the impact of theoretical uncertainties on the accuracy of
measurements involving hadronic jets. The analysis is performed using events
with a Z boson and a single jet observed in collisions at
= 1.96 TeV in 4.6 of data from the Collider Detector at
Fermilab (CDF). The transverse momenta (\pt) of the jet and the boson should
balance each other due to momentum conservation in the plane transverse to the
direction of the and beams. We evaluate the dependence of the
measured \pt-balance on theoretical uncertainties associated with initial and
final state radiation, choice of renormalization and factorization scales,
parton distribution functions, jet-parton matching, calculations of matrix
elements, and parton showering. We find that the uncertainty caused by parton
showering at large angles is the largest amongst the listed uncertainties. The
proposed method can be re-applied at the LHC experiments to investigate and
evaluate the uncertainties on the predicted jet energies. The distributions
produced at the CDF environment are intended for comparison to those from
modern event generators and new tunes of parton showering.Comment: Submitted to Nucl. Instr. and Meth.
Determination of the Jet Energy Scale at the Collider Detector at Fermilab
A precise determination of the energy scale of jets at the Collider Detector
at Fermilab at the Tevatron collider is described. Jets are used in
many analyses to estimate the energies of partons resulting from the underlying
physics process. Several correction factors are developed to estimate the
original parton energy from the observed jet energy in the calorimeter. The jet
energy response is compared between data and Monte Carlo simulation for various
physics processes, and systematic uncertainties on the jet energy scale are
determined. For jets with transverse momenta above 50 GeV the jet energy scale
is determined with a 3% systematic uncertainty
Cosmic ray tests of the D0 preshower detector
The D0 preshower detector consists of scintillator strips with embedded
wavelength-shifting fibers, and a readout using Visible Light Photon Counters.
The response to minimum ionizing particles has been tested with cosmic ray
muons. We report results on the gain calibration and light-yield distributions.
The spatial resolution is investigated taking into account the light sharing
between strips, the effects of multiple scattering and various systematic
uncertainties. The detection efficiency and noise contamination are also
investigated.Comment: 27 pages, 24 figures, submitted to NIM
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