As the LHC luminosity is ramped up to 3 × 10 34 cm 2 s 1 and beyond, the high rates, multiplicities, and energies of particles seen by the detectors will pose a unique challenge. Only a tiny fraction ...of the produced collisions can be stored offline and immense real-time data reduction is needed. An effective trigger system must maintain high trigger efficiencies for the physics we are most interested in while suppressing the enormous QCD backgrounds. This requires massive computing power to minimize the online execution time of complex algorithms. A multi-level trigger is an effective solution to meet this challenge. The Fast Tracker (FTK) is an upgrade to the current ATLAS trigger system that will operate at full Level-1 output rates and provide high-quality tracks reconstructed over the entire inner detector by the start of processing in the Level-2 Trigger. FTK solves the combinatorial challenge inherent to tracking by exploiting the massive parallelism of associative memories 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 relying on fast DSPs in modern commercial FPGAs. Overall, FTK is able to compute the helix parameters for all tracks in an event and apply quality cuts in less than 100 μs. The system design is defined and the performance presented with respect to high transverse momentum (high-p T ) Level-2 objects: b jets, tau jets, and isolated leptons. We test FTK algorithms using the full ATLAS simulation with WH events up to 3 × 10 34 cm 2 s 1 luminosity and compare the FTK results with the offline tracking capability. We present the architecture and the reconstruction performance for the mentioned high-p T Level-2 objects.
Beam tests of directly coupled scintillator tiles with MPPC readout Abu-Ajamieh, F.; Blazey, G.; Cole, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2011, Letnik:
659, Številka:
1
Journal Article
Recenzirano
We report on the response to a proton beam of scintillator tiles directly coupled at the face of the tile to multi-pixel photon counters. Detailed measurements with protons show that flat tiles have ...high response near the photon counters while concave tiles have uniform response suggesting that tiles with this versatile configuration can be tailored to a desired uniformity. The beam response is in qualitative agreement with the response to a non-triggered radioactive source and reveals additional spatial features.
A fast hardware tracker for the ATLAS trigger system Anderson, J.; Andreani, A.; Andreazza, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2013, Letnik:
718
Journal Article
Recenzirano
Odprti dostop
The Fast Tracker (FTK) processor is an approved ATLAS upgrade that will reconstruct tracks using the full silicon tracker at Level-1 rate (up to 100KHz). FTK uses a completely parallel approach to ...read the silicon tracker information, execute the pattern matching and reconstruct the tracks. This approach, according to detailed simulation results, allows full tracking with nearly offline resolution within an execution time of 100μs. A central component of the system is the associative memories (AM); these special devices reduce the pattern matching combinatoric problem, providing identification of coarse resolution track candidates. The system consists of a pipeline of several components with the goal to organize and filter the data for the AM, then to reconstruct and filter the final tracks. This document presents an overview of the system and reports the status of the different elements of the system.
The experimental results on the performance of the Metal/Resistor/Semiconductor (MRS) photodiode in the strong magnetic field of 4.4
T, and the possible impact of the quench of the magnet at 4.5
T on ...sensor's operation are reported. In addition, the experimental results on the performance of the extruded scintillator and WLS fiber, and various LEDs in the magnetic fields of 1.8 and 2.3
T, respectively, are detailed. The measurement method used is being described. The results of the work agree with the expectations that the LED, MRS and scintillator are not exhibiting sensitivity to the magnetic field presence. This result is essential for the design of the future electron–positron linear collider detector.
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