Speaker
Sebastien Prince
(McGill University (CA))
Description
After the current shutdown, the LHC is about to resume operation for a
new data-taking period, when it will operate with increased
luminosity, event rate and centre of mass energy. The new conditions
will impose more demanding constraints on the ATLAS online trigger
reconstruction and selection system. To cope with such increased
constraints, the ATLAS High Level Trigger, placed after a first
hardware-based Level-1 trigger, has been redesigned by merging two
previously separated software-based processing levels. In the new
joint processing level, the algorithms run in the same computing nodes,
thus sharing resources, minimizing the data transfer from the detector buffers
and increasing the algorithm flexibility.
The Jet trigger software selects events containing high transverse
momentum hadronic jets. It needs optimal jet energy resolution to help
rejecting an overwhelming background while retaining good efficiency for
interesting jets. In particular, this requires the CPU-intensive
reconstruction of tridimensional energy deposits in the ATLAS
calorimeter to be used as the basic input to the jet finding
algorithms. To allow this costly reconstruction step, a partial
detector readout scheme was developed, that effectively suppresses the
low activity regions of the calorimeter and significantly reduces the
needed resources. In this paper we describe the overall jet trigger
software and its physics performance. We then focus on detailed
studies of the algorithm timing and the performance impact of the full
and partial calorimeter readout schemes. We conclude with an outlook
of the jet trigger plans for the next LHC data-taking period.
| Oral or Poster Presentation | Oral |
|---|
Primary author
Sebastien Prince
(McGill University (CA))
