MALTA & BGV Discussion #2

Name: MALTA & BGV Discussion #2
Start: 2020-09-15T09:00:00+02:00
End: 2020-09-15T10:30:00+02:00
Location: No location set

Tuesday 15 Sept 2020, 09:00 → 10:30 Europe/Zurich

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Present: Heinz, Carlos, Valerio, Petra, Bernadette, James, Helene

Agenda: https://indico.cern.ch/event/954087/

Comments from module drawings:

Sensors:
- Total size: 21.3 × 23 mm² which includes 18.3 × 18.3 mm²sensitive area
- On one side: 3 mm for electronic connection; opposite side has the smallest dead area (50 µm distance at dicing) -> to place at inner radius on the beam pipe side,
- Left and right sides: 1 mm dead area
High density of chips => big amount of electronic connections => daisy chain the sensors 4 by 4 would help reducing a lot the required connections (necessity to check if the hit rate can allow it)
Better start with square sensor since MALTA v2 hasn't been tested yet (square shape with larger sensitive area is anyway better for us)
Final application: MALTA v3, that we can optimise for our needs
General interest in the 8+8 square chips configuration

Module design:

First tracking module: 1 or two concentric rings of sensors, the inner in 8+8 configuration
The sensors can't be placed corner to corner (place needed for wire bonds on sensor sides; to be seen if part of them can be removed): the more space the better
Divide rings into half moons to clamp around the beam pipe
Carbon Fiber structure to hold the sensors: ~100 µm at inner radius, more material on outer side
At sensor locations: square hole in CF structure under active area (continuous surface)
Possibility to place sensors from A and B layers back to back on the same CF support, but risky if a sensor fails; modularity is important but alignment will also be challenging

Simulations:

Start with 8+8 configuration and determine if we need 1 or 2 sensor rings on first tracking module (amount of tracks caught)
Determine how many tracking planes are required
Determine hit rate in the sensitive area of 4 chips on inner ring for compatibility with sensor daisy chain

Data transfer and routing considerations:

Front-end electronics location: depends on desired detector compactness; considering radiations, 10 cm away should be sufficient
Chain 4 sensors together (drive 4 sensors to 1 bus) would make sense:
- Development needed but should be feasible
- Denser configuration possible: bump bonding between chips
- Works for a curved arrangement
- /!\ hit rate must me compatible -> cf. simulations
  - 200 MHz allowed in sensor (provided the electronic can cope with this rate);
  - 1 MHz should be good for the daisy chain; depends also on trigger frequency
  - JS: Beam-gas collision rate shouldn't exceed this amount anyway to protect downstream elements (magnets or other BI equipment)
- Would allow 1 readout and only 4 FPGAs / module (in case 1 ring is sufficient coverage)
Possibility to build a test module on a PCB to test the module design on test beam
Cooling should already be considered for such a module:
- Thermal conduction at inner radius (sensitive area)
- Most of power consumption at outer radius: CO₂circulating in 2 mm diameter stainless steel or titanium pipes placed along outer radius of the ring

Summary and plans:

Module design will probably be challenging
BGV team will perform the actions listed in "Simulation" and give news when some results will be ready
MALTA team can then estimate if the sensors can be daisy chained and we can brainstorm on module design details

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