1. SLAC B-Factory BaBar Experiment WAN Requirements
Les Cottrell, SLAC
Presentation for NTON Research Partner Meeting, LLNL 7/30/97
2/19/2019
NTONC Research Partner Meeting, LLNL 7/30/97

2. NTONC Research Partner Meeting, LLNL 7/30/97
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
2/19/2019
NTONC Research Partner Meeting, LLNL 7/30/97

3. NTONC Research Partner Meeting, LLNL 7/30/97
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
“Factory” for large numbers of collisions (high intensity, high luminosity), high reliability, smooth operation
Asymmetric energies allow picking apart of the secondary decays of B mesons from the initial collision point
2/19/2019
NTONC Research Partner Meeting, LLNL 7/30/97

4. NTONC Research Partner Meeting, LLNL 7/30/97
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
> 500 physicists collaborating from > 70 sites in 10 countries
There are other requirements (e.g. SLD and GLAST), but not as large
2/19/2019
NTONC Research Partner Meeting, LLNL 7/30/97

5. Computational Requirements
Data
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
One STK Silo full of Redwood 40 Gbyte tapes = 300 Tbytes
Data is logged directly to OO Db (very aggressive)
CPU requirements are currently being actively evaluated, general feeling (based on previous experiments) is that 100,000 SpecInt92s is a big underestimate
Other analysis centers in France (IN2P3), UK (RAL), Italy.
2/19/2019
NTONC Research Partner Meeting, LLNL 7/30/97

6. 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 ~ Mbytes/sec, double to allow catch-up
Reconstruction turns raw (pulse heights etc.) into useful data (4 vectors etc.)
2/19/2019
NTONC Research Partner Meeting, LLNL 7/30/97

7. NTONC Research Partner Meeting, LLNL 7/30/97
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
Still need to understand how to parse the interactive analysis (bandwidth versus central capacity)
Previous experiments has demonstrated that loss of interaction badly impairs physics productivity
2/19/2019
NTONC Research Partner Meeting, LLNL 7/30/97

8. NTONC Research Partner Meeting, LLNL 7/30/97
Requirements
Large program builds between Institutions
Requires copying of 200 Mbytes per user in seconds
Expect 2 to 3 simultaneous users
2/19/2019
NTONC Research Partner Meeting, LLNL 7/30/97

9. NTONC Research Partner Meeting, LLNL 7/30/97
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)
Need higher quality video conferencing than available with standard MBONE, talking heads. Fall back to video conference rooms, audio (phone) & FAX. Have two (will be three soon) video conference rooms (circuit switched), but pretty much booked solid. Equipping BaBar group at S:LAC with VC capable desktops. Shows importance. Need to deploy more widely.
2/19/2019
NTONC Research Partner Meeting, LLNL 7/30/97

10. NTONC Research Partner Meeting, LLNL 7/30/97
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
More Information
SLAC
B Factory/PEPII
BaBar
Given the current state of the Internet, by necessity we have to limit our vision and use. It is hard to plan unless there is something to suggest it can be dramatically improved. The NTONC could provide important input and incentive to broaden our vision and get out of the chicken and egg problem.
2/19/2019
NTONC Research Partner Meeting, LLNL 7/30/97