1. Proposal to modify the TEC control loop schema
03/11/2019
Nick Lumb

2. Outline Present situation Proposed changes Implications Feasibility
Conclusions
03/11/2019
Nick Lumb

3. Physical connections (1)
03/11/2019
Nick Lumb

4. Physical connections (2)
03/11/2019
Nick Lumb

5. Present situation Loss of one ctrl ring => Up to 3 hits lost
03/11/2019
Nick Lumb

6. Proposed scheme (FED mapping unchanged) Loss of one ctrl ring
=> Only 1 hit lost
03/11/2019
Nick Lumb

7. FED / FEC mapping Present mapping Proposed mapping
Control loop (FEC) 1 2 3 4 5 6 7
4/4* 8 9 10 11 12
FED
Control loop (FEC) 1 2 3 4
4/5 5
5/6 6
7/8 7
9/9* 8
1*/2* 9
2*/3* 10
4*/5* 11
5*/6* 12
7*/8*
Tables are for 1/8 of one TEC
In new proposal, each FED maps to 2 control loops in general
Two additional FEC channels needed in new scheme
Total ctrl loops = 7
Total ctrl loops=9
03/11/2019
Nick Lumb

8. Implications Mapping APVs -> FEDs unchanged
Recently agreed table of readout ribbon lengths still applies -> F. Vasey can proceed with production order
In general, FEDs no longer read out APVs controlled by unique FEC (present disk 9 exception becomes the rule)
Requires 16 additional control loops per TEC:
Extra DOH
Extra control ribbons (routing and lengths to be determined)
Extra FEC transceivers
Cost: CHF 2500 / loop => CHF 80,000 total (2 TECs)
03/11/2019
Nick Lumb

9. Can it be done? FED synchronization, etc. (G. Hall / A. Marchioro)
Technically possible
But some reservations:
More complex FEC / FED mapping -> easier to make software mistakes
Unforeseen problems?
Cable links / ICB (W. Karpinski)
Thorough analysis concluded:
Disk 9 cabling and connector scheme can be extended to other disks with only minor modifications
No re-design of ICB necessary
03/11/2019
Nick Lumb

10. Conclusion
There is a finite (unknown) probability that, despite the built-in redundancy, a control loop will fail.
The present scheme is badly optimised in terms of maximizing physics performance in the event of a control loop failure.
Changing to a better scheme is technically possible.
Readout cabling and FED allocation unchanged.
Commissioning of DAQ will be slightly more complicated and prone to error.
Some minor hardware changes and cost implications.
Strongly recommend changing the scheme.
03/11/2019
Nick Lumb