1. DT & RPC Grounding STATUS
M. PEGORARO
INFN PD

2. DT Power & Grounding Layout for One Sector
BALCONY GND
Analog
P.S.
Digital
P.S.
Analog
P.S.
SECTOR
collector
Digital
P.S.
Analog
P.S.
Digital
P.S.
Analog
P.S.
Digital
P.S.
20m LV cables
15m LV cables
Split
board
Split
board
AC coupled LVDS links SL
cover
LVDS
MINI
CRATE SL
cover
LVDS
MINI
CRATE
HC & Al frame
HC & Al frame
LVDS SL
cover SL
cover
LVDS SL
cover
LVDS
MB1
MB4
Floating Power Supply and AC coupled LVDS links allow common mode freedom

3. Muon Chamber: LV & GND F Covers Q Superlayer Minicrate LV cables
Q Cover
From P.S.
GND
braids
LVDS
signals
LV conn.
Splitter
board
GND
braids
Honeycomb
& Al frame
The Al frame lodging the MINICRATE can be a very massive and low inductance GND joining FE covers
Splitter Board can be moved along F covers (for example on MB4 to reduce length of LV cables)
Signal currents from FE to MINICRATE are negligible (LVDS compatible signals differential termination).
If power return of MINICRATE and splitter board are connected in the same point then no current due to
internal signals flows out of this point and the chamber can be thought as an independent system.

4. Example MINICRATE lodgement
These 2 photos show an example of the GND connection between SLs and frame made with braid at each corner of one chamber.
Note also the copper connecting the external Al plates of each SuperLayer for hermeticity and the thickness of frame extrusions.
Totale chamber height is about 30cm.
The whole assembly will be insulated from magnet iron.

5. RPC Grounding Scheme

6. RPC Power & Grounding Layout for One Sector

7. Status
_ DT and RPC are glued together and surfaces can touch each other; also little gap and wide area
lead to a large capacitance between the 2 detectors. Ground coupling is then more than probable.
Connecting DT ground to balcony and RPC ground to iron would cause large loops.
_ RPC need to ground refer output from detector with link board located just outside iron sector.
_ DT should not need such reference; also their ground structure should be rather strong.
_ It's better perhaps to connect together their central ground points in a stable way and close to each
station in order to reduce loop area.
_ RPC also have large surface with little distance from magnet iron so large capacitance inbetween.
To avoid effects probably it's better to connect DT and RPC to iron at each station; the reference
to link boards can be brought with copper braids in tree configuration if really needed
(if the iron of one sector is not assuring contact).

8. Grounding DT & RPC SL F SL Q (MB3 only) MB3/4 SL F
Cu braid to link box
RB3/4
RB3/4
IRON
Connection
RB1/2_OUT
SL F
SL Q
IRON
IRON
MB1/2
SL F
RB1/2_IN

9. Proposal with Tree Connection