Speaker
A. Di Mattia
(INFN)
Description
The Atlas Level-2 trigger provides a software-based event selection
after the initial Level-1 hardware trigger. For the muon events, the
selection is decomposed in a number of broad steps: first, the Muon
Spectrometer data are processed to give physics quantities
associated to the muon track (standalone features extraction) then,
other detector data are used to refine the extracted features.
The "muFast" algorithm performs the standalone feature extraction,
providing a first reduction of the muon event rate from Level-1. It
confirms muon track candidates with a precise measurement of the
muon momentum. The algorithm is designed to be both conceptually
simple and fast so as to be readily implemented in the demanding
online environment in which the Level-2 selection code will run.
Never-the-less its physics performance approaches, in some cases,
those of the offline reconstruction algorithms. This paper describes
the implemented algorithm together with the software techniques
employed to increase its timing performance.
Primary author
A. Di Mattia
(INFN)
