1. Collimator Control Issue @P1 (SEUs & R2E Outlook)
M. Brugger on behalf of the R2E Project

2. Collimator Control Issue (SEEs?)
1st event:
5th Oct. 2010
MDC lost communication during SB or after dump
MDC remotely reset then failed and replaced
No interlock, no beam dump
After 14h of SB at 200x200b
At that time: SEE possible, judged unlikely
2nd event
27th Apr. 2011
MDC lost communication during SB at 480 vs 480 bunches.
No interlock, no beam dump
Remotely reset.
Access required: exchanged for precaution
Identified as SEE
3rd event:
1st May 2011
PRS rebooted during SB with 768 bunches.
Interlock, beam dump
Remotely reset.
Radiation levels in UJ14 during last week as high as the total until week before.
A few 106 HEH (> 20 MeV)
Clear signature of SEU
UJ14
MDC drives the motors (not interlocked)
PRS monitors the position (interlocked)
MDC
PRS

3. Collimator Control Operation
No safety issue on collimation control system observed during LHC operation
Detailed CNRAD analysis showed that there are possible (rare) failure modes which could affect the collimation control safety (loss of supervision)
Work-Around available and respective technical possibility already implemented in current design (software & hardware)
Activation of this procedure impacts operation:
Dump probability due to SEEs would increase
More false dumps (not radiation related) likely to occur
Detailed failure analysis required to draw final conclusion

4. Radiation Tests @CNRAD
Collimator control rack was tested at CNRAD in (qualitatively in order to identify failure mode and approximate failure probability)
Several failure modes detected:
MDC blocked into ARMED state
Communication loss with MDC
Resolvers steps lost.
MDC driver reading timeout
PXI rebooted itself
PRS power supply failure
Network communication temporarily lost
Permanent failure of motor driver
MDC CPU stuck error
MDC FPGA is stuck
First Soft Errors appeared with a high-energy hadron fluence of few 106cm-2 -> remote reset possible, dump depends on interlock
Hard Errors appeared with a high-energy hadron fluence of few 108cm-2 -> hardware exchange required
Event 1 & 2
Event 3

5. High-E Hadron Fluence [cm-2]
Radiation Levels UJ14/16
UJ14
UJ16
“Maze” Location
“Maze” Location
“Back” Location
“Back” Location
1RM01S
Measurements
High-E Hadron Fluence [cm-2]
Location
2010
Week 16
Week 17
Total
UJ14 Maze
~2x106
~4x106
~5x106
~1x107
UJ14 Back
few 105
few 106
UJ16 Maze
~1x106
~3x106
~6x106
UJ16 Back
RadMon
Voltage
2010
Week 16
Week 17
UJ13.1LM03S 5
821
1191
1655
UJ14.1LM01S 3 4 7
UJ14.1LM02S 60
111
130
UJ16.1RM01S 6 8
UJ16.1RM02S 39 65 99
UJ17.1RM03S
258
1624
2091

6. Other Equipment in UJ14/16
Power-Interlock (PIC),
Quench-Protection (QPS),
Cryogenics (Cryo),
Beam-Instrumentation (BI),
Power-Converters (PC),
Electrical Distribution (EL),
Current Lead Heaters,
Collimation (Collim.)
-> Equipment Inventory Available (EDMS: )
Other ‘weak links’ identified during CNRAD tests (not all equipment tested!)
Power-Converter Tests foreseen at H4IRRAD this year
UJ16
© A.L. Perrot, G. Spiezia

7. Other Areas
Weekly R2E radiation reports (

8. Mitigation Options Relocation & Shielding
Y. Muttoni, 05/04/2011
Courtesy M. Lazzaroni
LHC tunnel
IP1
Relocation
& Shielding
© A.L. Perrot, Y. Muttoni, M. Lazzaroni et. al.
Integration Study almost completed (ICL), ECR in preparation
Full relocation (Chamonix): 7months, 10 groups involved
Relocation of collimation-racks only?
First time estimate provided (dominated by cabling): about 2x2weeks (if high-priority and larger resources: feasible to do it faster?)
Remaining equipment, sensitivity mostly unknown
Other points: P8 ready (ECR), P5 frozen, P7 studied, few open issues (safe-room proposal in discussion/preparation)
© J.C. Guillaume

9. Summary SEE failures confirmed, limited impact on LHC operation
Rare failure modes might have a possible impact on control safety
Radiation levels consistent with FLUKA estimates
Mitigation options studied and prepared
Mitigation Measures:
Full implementation during long shut-down (complex work)
Preparation (anticipate activities) during xMasBreak
Most sensitive equipment could possibly be already relocated during xMasBreak
Technical stop periods (so far) considered too short to advance efficiently (preparation times are too important)
Open Points:
Safe-Rooms (P5 & P7)
Power-Converter and other equipment
EN/EL proposals to be iterated with safety
!!! Issue with North-Area: H4IRRAD MOST AFFECTED !!!

10. Conclusion Impact on 2011 operation likely to be acceptable
Mitigation solution studied and ready to be deployed
Experience during coming operation will show whether earlier relocation of collimation control needs to be anticipated
Other systems possibly affected (reasonable statistics for remaining 2011/12 operation requires at least 10x more cumulative luminosity)
Detailed failure analysis required to conclude on possible rare events as observed in CNRAD, destructive failures?
Solution prepared and ready to be applied (possible impact on operation efficiency)
High-priority to Power-Converter and other equipment tests in H4IRRAD should be given non-withstanding the delay in the start-up of the North Area

11. Backup