This paper introduces a Fast Bayesian Track Fit (FBTF) — a new algorithm for fitting tracks with Bremsstrahlung-induced energy losses. The FBTF algorithm combines a standard Kalman filter and a ...Bayesian estimator for fractional energy losses. The estimator uses computationally efficient approximations of the Bethe–Heitler distribution and measurement likelihood which allows analytical calculation of Bayesian integrals. The algorithm performance has been evaluated with simulated data using a simplified tracking scenario. The results regarding track parameter estimation quality and computing time are presented and compared with those obtained with a Gaussian-sum filter.
Results on the performance and viability of data-parallel algorithms on Graphics Processing Units (GPUs) in the ATLAS Level 2 trigger system are presented. We describe the existing trigger data ...preparation and track reconstruction algorithms, motivation for their optimization, GPU-parallelized versions of these algorithms, and a “client-server” solution for hybrid CPU/GPU event processing used for integration of the GPU-oriented algorithms into existing ATLAS trigger software. The resulting speed-up of event processing times obtained with high-luminosity simulated data is presented and discussed.
Triggering events with GPUs at ATLAS Kama, S; Soares, J Augusto; Baines, J ...
Journal of physics. Conference series,
01/2015, Letnik:
664, Številka:
9
Journal Article
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The growing complexity of events produced in LHC collisions demands increasing computing power both for the online selection and for the offline reconstruction of events. In recent years there have ...been significant advances in the performance of Graphics Processing Units (GPUs) both in terms of increased compute power and reduced power consumption that make GPUs extremely attractive for use in a complex particle physics experiments such as ATLAS. A small scale prototype of the full ATLAS High Level Trigger has been implemented that exploits reconstruction algorithms optimized for this new massively parallel paradigm. We discuss the integration procedure followed for this prototype and present the performance achieved and the prospects for the future.
This work describes a new guidance algorithm against maneuvering decelerating target based on the concept of information sets (IS). As an example of guidance problem, a model of defense scenario ...against reentering ballistic missile is considered. In this scenario, a maneuverable decelerating target is to be destroyed by a hit-to-kill interceptor outfitted with an infrared (IR) array seeker and lateral impulse thrusters. The key element of the proposed approach is a description of the "interceptor-target" system state by means of IS. The results of Monte Carlo (MC) tests of the developed algorithm are presented.
The ATLAS Level 2 Trigger algorithm for simultaneous pattern recognition and track fitting in the ATLAS Transition Radiation Tracker (TRT) is presented. The algorithm employs the Probabilistic Data ...Association Filter (PDAF) as a tool for “hit-to-track” association and track parameter estimation. An introduction to the PDAF technique and details of its implementation for tracking and electron identification in the TRT are given. The results of tests on simulated data with high track multiplicity are presented and discussed.
The new track reconstruction program CATS developed for the Vertex Detector System of the HERA-B experiment at DESY is presented. It employs a cellular automaton for track searching and the Kalman ...filter for track fitting. This results in a very fast algorithm that combines highly efficient track recognition with accurate and reliable track parameter estimation. To reduce the computational cost of the fit an optimized numerical implementation of the Kalman filter is used. Alternative approaches to the track reconstruction in the VDS are also discussed.
Since 1999, after extensive tests on simulated data, CATS has been employed to reconstruct experimental data collected in HERA-B. Results regarding tracking performance, the accuracy of track parameter estimates and CPU time consumption are presented.
The paper describes track reconstruction package OTR/ITR-CATS developed for the Pattern Tracker of the HERA-B experiment. This package employs a combined approach for track reconstruction based on ...the use of a cellular automaton for track searching and the Kalman filter techniques for track fitting. A similar reconstruction strategy is already successfully applied to the Vertex Detector System (VDS) (Nucl. Instr. and Meth. A 489 (2002) 389). However, hit efficiencies and resolutions of the Pattern Tracker lower than those of the VDS require much more delicate implementation of the method.
The package developed has been tested on simulated data. The results of the tests regarding reconstruction efficiency, accuracy of estimates and computing time are presented.
The unprecedented rate of beauty production at the LHC will yield high statistics for measurements such as CP violation and Ba oscillations and will provide the opportunity to search for and study ...very rare decays, such as B → μμ. The trigger is a vital component for this work and must select events containing the channels of interest from a huge background in order to reduce the 40 MHz bunch crossing rate down to 100-200 Hz for recording, of which only a part will be assigned to B-physics. Requiring a single or di-muon trigger provides the first stage of the B-trigger selection. Track reconstruction is then performed in the Inner Detector, either using the full detector, at initial luminosity, or within Regions of Interest identified by the first level trigger at higher luminosities. Based on invariant mass, combinations of tracks are selected as likely decay products of the channel of interest and secondary vertex fits are performed. Events are selected based on properties such as fit quality and invariant mass. We present fast vertex reconstruction algorithms suitable for use in the second level trigger and event filter (level three). We discuss the selection software and the flexible trigger strategies that will enable ATLAS to pursue a B-physics programme from the first running at a luminosity of about 1031cm-2s-1 through to the design luminosity running at 1034cm-2s-1.
ATLAS is a general purpose particle physics experiment located on the LHC collider at CERN. The ATLAS Trigger system consists of two levels, the first level (L1) implemented in hardware and the High ...Level Trigger (HLT) implemented in software running on a computing cluster of commodity CPUs. The HLT reduces the trigger rate from the 100 kHz L1 accept rate to 1 kHz for recording, requiring an average per-event processing time of ~300 ms for this task. The HLT selection is based on reconstructing tracks in the Inner Detector and Muon Spectrometer and clusters of energy deposited in the calorimeters (electromagnetic and hadronic). Performing this reconstruction within the available HLT computing cluster resources presents a significant challenge. Future HLT upgrades will result in higher detector occupancies and, consequently, will harden the reconstruction constraints. General purpose Graphics Processor Units (GPGPU) are being evaluated for possible future inclusion in an upgraded HLT computing cluster. We report on a demonstrator that has been developed consisting of GPGPU implementations of the calorimeters clustering and Inner Detector and Muon tracking algorithms integrated within the HLT software framework. We give a brief overview of the algorithm implementation and present preliminary measurements comparing the performance of the GPGPU algorithms with the current CPU versions.
Consideration was given to a new approach to constructing the algorithms intended to track moving objects (true targets) in the environment of false targets. The approach relies on a combination of ...the Reid multiple-hypotheses method and the information-set filtration. It was illustrated by the example of tracking “heavy” true and “light” false targets moving in air along ballistic trajectories.
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