Speaker
Dr
Christopher Pinkenburg
(BROOKHAVEN NATIONAL LABORATORY)
Description
The PHENIX experiment took 2*10^9 CuCu events and more than 7*10^9 pp events during
Run5 of RHIC. The total stored raw data volume was close to 500 TB.
Since our DAQ bandwidth allowed us to store all events selected by the low level
triggers, we did not filter events with an online processor farm which we refer to as
level 2 trigger. Instead we ran the level 2 triggers offline in the PHENIX counting
house on a local Linux cluster to select events for a priority reconstruction. These
events were transferred to an offsite computing facility for fast reconstruction and
analysis - which also provided important fast feedback in terms of achievable physics
goals. In addition a subset of the minimum bias data was reconstructed immediately in
the PHENIX counting house for other physics analysis and estimation of the level 2
trigger bias.
This approach requires a fast availability of the calibrations which are necessary
for the reconstruction. These calibrations are performed in parallel to the level 2
filtering effort under a common framework which provides access to events, database
connectivity and keeps track of successes and failures. The resulting calibration
constants are stored on a run by run basis in a PostgreSQL data base which is
distributed to the offsite computing facilities.
We will present the experiences of the PHENIX online computing for Run5 and the
future developments and improvements for the upcoming Runs.
Author
Dr
Christopher Pinkenburg
(BROOKHAVEN NATIONAL LABORATORY)