1. Hall D Trigger and Data Rates
Elliott Wolin
Hall D Electronics Review
Jefferson Lab
23-Jul-2003

2. Outline Rates from Design Report Comparison with LHC,CLAS…
Additional Considerations
DAQ Challenges

3. 1. Rates from Design Report
High trigger rate – 200 KHz
Deadtimeless, pipelined front ends
Small event size – 5 KB
Small Level 1 rejection rate – factor of 2
Modest rate off detector – 1 GB/sec
Modest Level 3 rejection – factor of 10
Modest cpu needed in Level 3 – 0.1 SPECint
High rate to tape – 100 MB/sec

4. 1. Rates, con’t

5. 2. Comparison with LHC, CLAS…
Compared to LHC, Hall D has:
Similar (LHCb, BTev) or higher trigger rate
Much smaller events
Much smaller rate off detector
Much smaller total trigger rejection
Similar rate to tape
Less cpu/evt needed in Level 3

6. 2. Comparison with LHC, CLAS…
Compared to CLAS, Hall D has:
Much higher trigger rate
200 KHz vs 3 KHz
Same size events
Approximately the same number channels
Much higher rate off detector
1 GB/s vs 25 MB/s
Factor 10 Level 3 rejection
CLAS has no Level 3
Factor 4 higher rate to tape
100 MB/s vs 25 MB/s

7. Hall D
KTev
KTeV
CLAS

8. Atlas
BTev
Hall D
CMS
KTev, CDF, DO, BaBar, CLAS

9. 3. Additional Considerations
Can not interrupt ROC every event (200 KHz)
Event blocking in front end cpu’s
Timing and trigger distribution
Note that CLAS has:
25 crates
1 Trigger supervisor
1 Event Builder and 1 Event Recorder
No Level 3 farm

10. Hall D DAQ Baseline Architecture
50-100
front-end crates
Gigabit switch
200 KHz
8 event builders
4 Gigabit switches
200 Level 3 Filter Nodes
4 event recorders
Network connection
to silo 20 KHz
4 tape drives

11. 3. Additonal Considerations, con’t
Crates vs networked front end boards?
If crates used, VME vs CPCI vs ?
(RT)Linux vs VXWorks in front end cpu’s?
Need low-latency interrupt in front end cpu’s?
Location of electronics, crates?
Grounding design?

12. 4. DAQ Challenges All problems solved somewhere, many in CLAS
But new to JLab/CODA:
Timing distribution
Event blocking
Many more front end crates
Multiple event builders/recorders
Large Level 3 farm
Multiple, simultaneous DAQ systems
Need for fault tolerance
Integration with control system
How are we going to do it?
See next talk…

13. Backup slides

14. 3. Comparison, con’t Event Size L1 Input Rate L1 output L2 output
KTev
8 KB
100 KHz
800 MB/s
20 KHz
160 MB/s
2 KHz
7 MB/s
CDF
270 KB
50 KHz
13 GB/s
300Hz
80 MB/s
80 Hz
23 MB/s D0
250 KB
10 KHz
2.5 GB/s
1 KHz
250 MB/s
70 Hz
13 MB/s
BaBar
33 KB
(1200 L1)
2.4 GB/s
None
(65 MB/s)
100 Hz
4 MB/s
BTev
50-80 KB
800 GB/s
80 KHz
8 GB/s
4 KHz
200 MB/s

15. 3. Comparison, con’t Event Size L1 Input Rate L1 output L2 output
Atlas
1-2 MB
75 KHz
100 GB/s
3 KHz
5 GB/s
200 Hz
300 MB/s
CMS
1 MB
100 KHz
100 Hz
100 MB/s
CLAS
6 KB
4 KHz
4KHz
25 MB/s
Hall D
5 KB
400 KHz
200 KHz
1 GB/s
none
20 KHz