Speaker
D. Winter
(COLUMBIA UNIVERSITY)
Description
The PHENIX detector consists of 14 detector subsystems. It is designed such
that individual subsystems can be read out independently in parallel as well
as a single unit. The DAQ used to read the detector is a highly-pipelined
parallel system. Because PHENIX is interested in rare physics events, the DAQ
is required to have a fast trigger, deep buffering, and very high bandwidth.
The PHENIX Event Builder is a critical part of the back-end of the PHENIX DAQ.
It is reponsible for assembling event fragments from each subsystem into
complete events ready for archiving. It allows subsystems to be read out
either in parallel or simultaneously and supports a high rate of archiving.
In addition, it implements an environment where Level-2 trigger algorithms may
be optionally executed, providing the ability to tag and/or filter rare
physics events.
The Event Builder is a set of three Windows NT/2000 multithreaded executables
that run on a farm of over 100 dual-cpu 1U servers. All control and data
messaging is transported over a Foundry Layer2/3 Gigabit switch. Capable of
recording a wide range of event sizes from central Au-Au to p-p interactions,
data archiving rates of over 400 MB/s at 2 KHz event rates have been achieved
in the recent Run 4 at RHIC. Further improvements in performance are expected
from migrating to Linux for Run 5.
The PHENIX Event Builder design and implementation, as well as performance and
plans for future development, will be discussed.
Primary author
D. Winter
(COLUMBIA UNIVERSITY)
