SVT Improvement (Track counting in GhostBuster board)

1
SVT Improvement (Track counting in GhostBuster
board)

• Motivation
• Processing time of L2 can be significantly
  reduced (2-3us level?) using of good tracks
  counted by SVT GhostBuster(GB) board. (good
  track Ptgt2GeV/c, chisqlt15, d0gt100um)
• studied by Kristian Hahn, idea Bill
  Ashmanskas
• 
  Jonathan Lewis
• Number of good track(s) gt 0 and gt1 (2 bit
  assignment) in SVT End of Event (EoE) could be
  useful for the fast decision of L2 alpha program.

2
Track counting in SVT GB board (cont)

• Changing GB firmware is not so hard, takes 2
  weeks including test.
• Therefore, only discussion for 2 bit assignment
  of EoE is needed

24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
HD DS 1 1 L2B L2B L1T L1T Error Flags Error Flags Error Flags Error Flags Error Flags Error Flags Error Flags Error Flags PA Event Tag (BC) Event Tag (BC) Event Tag (BC) Event Tag (BC) Event Tag (BC) Event Tag (BC) Event Tag (BC) Event Tag (BC)
Essential for SVT and/or L2
Note bit 9 Parity error bit 10
Lost sync bit 11 FIFO overflow
bit 12 Invalid data bit 13 Internal
overflow bit 14 Truncated Output
bit 15 G-link lost lock bit 16
Parity error to L2?
Relatively low priority
(1) There are almost no resources without
overriding error bit. (Bit 16 is not used yet,
but useful in future tracklist overrides ) (2)
bit 17, 18 are useful to check the data.
(bit 17 may be used in diff Pt cut) (3) I
proposed the overriding the bit 13(Ngt0) and
14(Ngt1). Bit 13 and 14 is not a real error
condition.
3
Current situation for error bit

• bit 13 and 14 error is naturally occurred in SVT
  and indeed happened in almost every events. They
  are set so often and carries almost no
  information.
• bit 15 is never set (if this happens, SVT stopped
  processing). So, this bit is also OK to use.
• These can be checked by SPYMON until the GB
  though SVTD information for overridden error bits
  will be lost. (since SVTD readout is after the EE
  modification)

GB timing SPY SVTD
L2 track list
GB track Proc.
Candidate for EE modification
4
Summary

• Counting the number of good tracks inside GB
  could improve the L2 processing time
  significantly. (worth while trying)
• Firmware changing is not so hard. It takes a
  couple of weeks including the test,
  optimistically.
• I propose bit 13 and 14 overridden. (If there is
  no strong objections, this is the simplest and
  safest for current SVT configuration).