Progress with grounding and shielding

SCT system test

Contents

• Description of grounding scheme

• Noise injection technique

• Results - new option!!

Grounding Schemes

50μm

PPF1

PPF0

VME

Shunt shield

Cooling Block + Disk

DGND

VDD

30m

PPF2100μm

Choke

ModuleWiggly

Support frame

Cu Box

50μm

PPF1

PPF2

PPF0

VME

Cooling Block + Disk

DGND

VDD

30m100μm

Choke

ModuleWiggly

Support frame

Cu Box

Ned’s

Smithy’s

@ PPF1 - HV return line shorted to shield HV line AC coupled to shield via 10nF cap

10nF

@ PPF1 for both schemes

• VDD to DGND 4.7μF

• VCC to AGND 4.7μF

• VCC, VDD, AGND, DGND, all signal lines to shield 1μF ()

• HV to HV-return 10nF

On Disk

 

Support structurePPF0

Shield

DGND

Thermal

Shield

Radial andannular Alfoils

Coolingpipes +blocks

OR

GND

Disk

OR n/c

Noise injection technique• Single threshold scan with

2fC injected charge– reference scan– scan under different

conditions

• Assume gain = 55

• plot noise difference with respect to the reference

Front side master

Backsidemaster chip

Backsideend chip

Results noise injection into tapesbefore some modifications

Red- Smithy’sBlack - Ned’s

Best Scheme - New Option

• ADD DC connection at PPF0 from DGND to shield to Smithy’s scheme

• Noise reduced to order 300 electrons from 2500!

• BUT not been repeated since.– More measurement are on going