Speaker
Dr
gokhan unel
(UNIVERSITY OF CALIFORNIA AT IRVINE AND CERN)
Description
The ATLAS experiment at LHC will start taking data in 2007. As preparative work, a
full vertical slice of the final higher level trigger and data acquisition (TDAQ)
chain, "the pre-series", has been installed in the ATLAS experimental zone. In the
pre-series setup, detector data are received by the readout system and next
partially analyzed by the second level trigger (LVL2). On acceptance by LVL2 all
data are passed through the event building (EB) and the event filter (EF) farms;
selected events are written to mass storage.
The pre-series setup was used to validate the technology and implementation choices
by comparing the final ATLAS readout requirements, to the results of performance,
functionality and stability studies. These results were also used to validate the
simulations of the components and subsequently to model the full size ATLAS system.
The model was used to further confirm the ability of the final system to meet the
requirements and to obtain indications on event building rate, latencies of the
various stages, buffer occupancies of the network switches, etc. This note summarizes
these studies together with other optimization investigations such as number of
application instances per CPU and choice of network protocols. For the first time,
realistic LVL2 and EF algorithms were utilized in such a large and realistic
test-bed. Continuous deployment and test will take place during the assembly of the
full ATLAS TDAQ system. The interfacing of the pre-series with one of the
sub-detectors has also been successfully tested in ATLAS experimental zone.
We show that all the components which are not running reconstruction algorithms match
the final ATLAS requirements. For the others, we calculate the amount of time per
event that could be allocated to run these not yet finalized algorithms. Based on the
calculations, we estimate the computing power necessary for using the present
implementation of the ATLAS reconstruction software.
Primary author
Dr
gokhan unel
(UNIVERSITY OF CALIFORNIA AT IRVINE AND CERN)
Co-author
TDAQ ATLAS
(many)
