1. CERN – 7 Oct 04 1 LHCb Muon Grounding Anatoli Katchouk CERN Alessandro Balla, Paolo Ciambrone, Maurizio Carletti, Giovanni Corradi, Giulietto Felici, Rosario Lenci INFN - Laboratori Nazionali di Frascati Maurizio Gatta INFN - RomaII

2. CERN – 7 Oct 04 2 Grounding components Grounding HV connections Front End Off-chamber connections Safety connections LVPS connections Front End On-chamber connections

3. CERN – 7 Oct 04 3 Reference ground Safety ground Signal ground Grounding, shielding and power distribution must be handled together to avoid EMI pickup and preserve signal integrity Signal ground : on-detector electronics ground reference Reference ground : off-detector electronics ground reference Safety ground : connection to earth How many grounds ?

4. CERN – 7 Oct 04 4 Grounding components Grounding HV connections Front End Off-chamber connections Safety connections LVPS connections Front End On-chamber connections

5. CERN – 7 Oct 04 5 Z1 Safety connections Detector must be connected to earth for safety reasons Chamb 1Chamb 2 Chamb 3 Chamb … Copper braid (sitting on the edge of the wall) Z2 Z3 Z4 Zstrip

6. CERN – 7 Oct 04 6 Grounding components Grounding HV connections Front End Off-chamber connections Safety connections LVPS connections Front End On-chamber connections

7. CERN – 7 Oct 04 7 HV supply voltage is distributed using shielded cables Shield can not be connected to ground to both sides to avoid ground loops A resistor (~ 1-10 k) is used on the detector side to break the loop Some current will flow through the low resistance safety earth network (unavoidable) HV connections HV PS Load 1-10 k

8. CERN – 7 Oct 04 8 Grounding components Grounding HV connections Front End Off-chamber connections Safety connections LVPS connections Front End On-chamber connections

9. CERN – 7 Oct 04 9 Front end on-chamber connections (I) SPBCARDIACOPB LVPS regulator board Safety ground must be connected to FC through a low impedance path (copper braid) Faraday cage is the chamber signal ground Ground connection LVPS connector CARDIAC connector Faraday cage

10. CERN – 7 Oct 04 10 Front end on-chamber connections (II)

11. CERN – 7 Oct 04 11 Grounding components Grounding HV connections Front End Off-chamber connections Safety connections LVPS connections Front End On-chamber connections

12. CERN – 7 Oct 04 12 Data transmission between front end electronics and DAQ system is implemented via differential electrical connections (LVDS)  good immunity to common mode noise As we will use shielded cables one end is connected directly to ground while the other end could be connected to ground through a capacitor to avoid low frequency loops Front End Off-chamber connections Shielded Twisted cable Exceeding the common mode range can damage LVDS driver/receiver circuits |V A -V B | must be less than the LVDS common mode range A B

13. CERN – 7 Oct 04 13 Grounding components Grounding HV connections Front End Off-chamber connections Safety connections LVPS connections Front End On-chamber connections

14. CERN – 7 Oct 04 14 LVPS connections (I) Number of Chambers FEE boards x Chamber Icc x Chamber (A) Icc (A) x Station Total (A) Current M1 R419231,38264,96 927,36 R348125,52264,96 R224 11,04264,96 R1122411,04132,48 M2/M3 R41923 1,38264,96 850,08 R34812 5,52264,96 R22422 10,12242,88 R11214 6,4477,28 M4/M5 R4192 31,38264,96 529,92 R348 62,76132,48 R224 62,7666,24 R112 5,5266,24 Total4217,28 Front end current requirements ( LHCb 2004-006 internal note) CARIOCA135 mA @ 2.5 V DIALOG160 mA @ 2.5 V

15. CERN – 7 Oct 04 15 LVPS connections (II) 40 A Module N 8 Chambers @ 4.8 A M1R3 M2/M3-R3 M4/M5-R1 N 16 Chambers @ 2.4 A M4/M5-R3 N 32 Chambers @ 1.2 A M1R4 M2/M3-R4 M4/M5-R4 LVPS Patch panel & fuses Chamber 1 Chamber 2 Chamber n

16. CERN – 7 Oct 04 16 Conclusions The on-chamber shielding and grounding scheme has been studied and successfully tested in several TB The proposed grounding scheme requires : FC as detector signal ground reference Floating low voltage power supply Chamber connected only to the safety ground High voltage ground broken by resistor The maximum ground voltage difference between on- detector and off-detector electronics must be less than LVDS allowed common voltage