Conference Paper

Design and performance of the level 1 calorimeter trigger for the BABAR detector

Dept. of Phys., Imperial Coll. of Sci., Technol. & Med., London
DOI: 10.1109/NSSMIC.2000.949930 Conference: Nuclear Science Symposium Conference Record, 2000 IEEE, Volume: 2
Source: IEEE Xplore

ABSTRACT Since May 1999 the BABAR detector has been taking data at the
PEP-II asymmetric electron-positron collider at the Stanford Linear
Accelerator Center, California. This experiment requires a very large
data sample and the PEP-II accelerator uses intense beams to deliver the
high collision rates needed. This poses a severe challenge to the BABAR
trigger system, which must reject the large rate of background signals
resulting from the high beam currents whilst accepting the collisions of
interest with very high efficiency. One of the systems that performs
this task is the Level 1 Calorimeter Trigger, which identifies energy
deposits left by particles in the BABAR calorimeter. It is a digital,
custom, fixed latency system which makes heavy use of high-speed FPGA
devices to allow flexibility in the choice of data filtering algorithms.
Results from several intermediate processing stages are read out,
allowing the selection algorithm to be fully analysed and optimized
offline. In addition, the trigger is monitored in real time by sampling
these data and cross-checking each stage of the trigger calculation
against a software model. The design, implementation, construction and
performance of the Level 1 Calorimeter Trigger during the first year of
BABAR operation are presented

8 Reads
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The BABAR detector, situated at the SLAC PEP-II asymmetric e{sup +}e⁻ collider, has been recording data at energies on and around the Υ(4S) resonance since May 1999. In this paper, we briefly describe the PEP-II B Factory and the BABAR detector. The performance presently achieved by the experiment in the areas of tracking, vertexing, calorimetry and particle identification is reviewed. Analysis concepts that are used in the various papers submitted to this conference are also discussed.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The environment of the high-luminosity PEP-II machine poses unique design challenges for the trigger system of the BABAR detector. These led to the adoption of a real-time parallel pipelined architecture for the trigger electronics which departs significantly from previous implementations at conventional e/sup +/e/sup -/ experiments. One challenge for the trigger designer lies in detecting low multiplicity physics events with high efficiency while keeping the background rate within the data acquisition limits. To achieve this difficult task, creative and innovative high-speed trigger algorithms were designed, simulated and implemented in Field Programmable Gate Arrays, using advanced CAD/CAE tools. The simulation results indicate that these algorithms will be able to perform all required tasks quickly and efficiently. This paper describes the design of the Level 1 Drift Chamber Trigger System of the BABAR detector, including the trigger algorithms, design and test methodology of the implementation, as well as test and simulation results.
    IEEE Transactions on Nuclear Science 01/2000; DOI:10.1109/23.819272 · 1.28 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The BABAR experiment at the Stanford Linear Accelerator Center is designed to perform a search for CP violation by analyzing the decays of a very large sample of B and B¯ mesons produced at the high luminosity PEP-II accelerator. The data acquisition system must cope with a sustained high event rate, while supporting real time feature extraction and data compression with minimal dead time. The BABAR data acquisition system is based around a common VME interface to the electronics read-out of the separate detector subsystems. Data from the front end electronics is read into commercial VME processors via a custom “Personality Card” and PCI interface. The commercial CPUs run the Tornado operating system to provide a platform for detector subsystem code to perform the necessary data processing. The data is read out via a non-blocking network switch to a farm of commercial UNIX processors. The current implementation of the BABAR data acquisition system has been shown to sustain a level 1 trigger rate of 1.3 kHz at an event size of 25 kbytes and with negligible deadtime. Upgrades currently in development will permit the system to support the design Level 1 rate of 2 kHz with negligible deadtime
    Real Time Conference, 1999. Santa Fe 1999. 11th IEEE NPSS; 02/1999


8 Reads
Available from