SLAC%20B-Factory%20BaBar%20Experiment%20WAN%20Requirements

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SLAC B-Factory BaBar Experiment WAN Requirements

• Les Cottrell, SLAC
• ltcottrell_at_slac.stanford.edugt
• http//www.slac.stanford.edu/grp/scs/net/talk/nton
  -jul97/
• Presentation for NTON Research Partner Meeting,
  LLNL 7/30/97

2
What is SLAC?

• Stanford Linear Accelerator Center
• Department of Stanford, funded by DOE
• Mission
• Basic experimental research in Elementary
  Particle Physics
• Accelerator Research design
• Synchrotron Radiation research

3
What is the B Factory?

• PEP-II B Factory
• Presidential initiative, started 1994
• SLAC, LBNL, LLNL collaboration
• Energies similar to those immediately after big
  bang
• Chosen to create particles (B mesons) made of
  bottom quarks
• Asymmetric Electron - Positron storage rings

4
What is BaBar?

• BaBar
• Large detector to surround collision point at B
  Factory
• Look at decays of B particles
• Investigate central prediction of Standard Model
  explanation of CP violation which results in the
  existence of large calculatable asymmetries in
  decays of B0s into CP eigenstates
• Start taking physics data in 1999
• gt 500 physicists collaborating from gt 70 sites in
  10 countries
• There are other requirements (e.g. SLD and
  GLAST), but not as large

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Computational Requirements

• Data
• 300 - 500 Tbytes / year
• HPSS Object Oriented Db
• Computing
• Expect 100,000 SpecInt92s
• Farms of pizza boxes for simulation (low I/O)
  data reconstruction
• Looking at SMPs for higher I/O
• compiling and linking
• interactive analysis, databases
• Unix today, but ...
• Significant analysis centers not at SLAC

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Requirements for High Speed Networking

• Copying of reconstructed data sets to other sites
  (e.g. LBNL)
• enable use of non-SLAC compute cycles for
  reconstruction
• backup, disaster recovery
• sustained rate 10-20 Mbytes/sec, double to
  allow catch-up

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Requirements

• Interactive event analyses by people at remote
  sites
• Needs several Mbytes/sec per user and expect
  several simultaneous users.
• Slower rates will mean use batch not interactive

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Requirements

• Large program builds between Institutions
• Requires copying of 200 Mbytes per user in 20-60
  seconds
• Expect 2 to 3 simultaneous users

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Requirements

• Enable high quality collaboratory work
• video and data conferencing (say 5-20
  simultaneous such conferences or about
  4Mbytes/sec for long periods)
• remote real-time data monitoring, experiment
  feedback
• remote presence at experiment (e.g. full motion
  video)
• evaluate effectiveness of virtual experiment /
  reality etc. for HEP (build on LBNL setup)

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Summary

• Peak needs several hundreds of Mbits/sec
• Want to start soon to understand how to use, to
  change mind-sets etc. and build to production use
  in late 1998-99.
• More Information
• http//www.slac.stanford.edu/
  SLAC
• http//www.slac.stanford.edu/welcome/pepii.html
  B Factory/PEPII
• http//www.slac.stanford.edu/welcome/babar.html
  BaBar