Speaker
M. Richter
(Department of Physics and Technology, University of Bergen, Norway)
Description
The ALICE experiment at LHC will implement a High Level Trigger
System, where the information from all major detectors are combined,
including the TPC, TRD, DIMUON, ITS etc. The largest computing
challenge is imposed by the TPC, requiring realtime pattern
recognition. The main task is to reconstruct the tracks in the TPC,
and in a final stage combine the tracking information from all
detectors. Based on the physics observables selective readout is done
by generation of a software trigger (High Level Trigger), capable of
selecting interesting (sub)events from the input data stream.
Depending on the physics program various prosessing options are
currently being developed, including region of interest processing,
rejecting events based on software trigger and data compression
schemes. Examples of such triggers are verification of candidates for
high-pt dielectron heavy-quarkonium decays, momentum filter to enhance
the open-charm signal, high-pt jets selection etc.
Technically the HLT system entails a very large scale processing farm
with about 1000 active processors. The input data stream is designed
for 25 GB/sec. The system nodes will be interfaced to the local data
concentrators of the DAQ system via optical fibers receiving a copy of
the raw data.
The optical fibers will be connected to the PCI-bus of HLT nodes using
a custom PCI card. These cards provide a co-processor functionality
for the first steps of the pattern recognition.
The talk will give an overview of the HLT project and will focus on
the latest results regarding efficient data compression and trigger
performance.
Primary authors
A. Vestbo
(Department of Physics and Technology, University of Bergen, Norway)
A. Wiebalck
(Kirchhoff Institute for Physics, University of Heidelberg, Germany)
B. Skaali
(Department of Physics, University of Oslo, Norway)
C. Loizides
(Institute for Nuclear Physics, University of Frankfurt, Germany)
D. Rohrich
(Department of Physics and Technology, University of Bergen, Norway)
H. Helstrup
(Faculty of Engineering, Bergen University College, Norway)
H. Tilsner
(Kirchhoff Institute for Physics, University of Heidelberg, Germany)
K. Ullaland
(Department of Physics and Technology, University of Bergen, Norway)
M. Richter
(Department of Physics and Technology, University of Bergen, Norway)
R. Stock
(Institute for Nuclear Physics, University of Frankfurt, Germany)
T. Alt
(Kirchhoff Institute for Physics, University of Heidelberg, Germany)
T. Vik
(Department of Physics, University of Oslo, Norway)
T.M. Steinbeck
(Kirchhoff Institute for Physics, University of Heidelberg, Germany)
V. Lindenstruth
(Kirchhoff Institute for Physics, University of Heidelberg, Germany)
