2,993 research outputs found
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
Near-threshold Lambda(1520) production by the gamma p -> K+Lambda(1520) reaction at forward K+ angles
Differential cross sections and photon-beam asymmetries for the gamma p -> K+
Lambda(1520) reaction have been measured with linearly polarized photon beams
at energies from the threshold to 2.4 GeV at 0.6<cos(theta)<1. A new bump
structure was found at W=2.11 GeV in the cross sections. The bump is not well
reproduced by theoretical calculations introducing a nucleon resonance with
J<=3/2. This result suggests that the bump might be produced by a nucleon
resonance possibly with J>=5/2 or by a new reaction process, for example an
interference effect with the phi photoproduction having a similar bump
structure in the cross sections.Comment: 5 pages, 4 figures, published in Phys. Rev. Let
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