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

Agenda: https://indico.cern.ch/event/949529/

BGV project presentation (BK):

Cf. slides
Early stage of the design, the distance gas target - first detector plane is not fixed yet (as close as possible, few cm)
NIEL dose calculation ongoing with FLUKA; (HP) should be around 1×10¹⁵ n_eq/cm²
(HP) a G4 simulation of MALTA is available

MALTA sensor details:

Time resolution: between 2 to 5 ns
No trigger system in the chip (events collected continuously, asynchronously), but possibility to correlate events using time stamps in FPGA system, where hit can be associated to bunches
Price: 4 to 5 times cheaper than hybrid detectors
Material budget: Sensor can be thinned down to 50 µm
Pixel size 36 × 36 µm²
Sensitive area 18.3 × 18.3 mm²

Detectors positioning possibilities, modules design:

As close as possible to the beam pipe, which should be around 45 mm diameter
Round beam pipe/square detectors => need for sensor overlapping
BGV detector modules outer radius to be determined, trade off between amount of tracks caught and sensitive area (cost)
Draw from ATLAS inner ring pixel detector modules design (single chip modules, similar inner radius)
Or similar design than LHCb VELO:
- 2 half-rings clamped around the beam pipe, containing as many modules as the cables allow;
- Possibility to place sensors on both sides of the module with 20-30% surface overlap;
- 3 ring layers separated by 20 to 30 cm: 3 to 6 hit points per track.
Possibility to tilt the modules to minimise the particles' path into detectors material -> might not be needed with 50 µm thick sensors.
Could also try with 2 concentric layers of chips

MALTA chip presentation (HP):

MALTA-Cz:
- Tested with 100 Hz/cm²and 10¹⁵n_eq/cm²
- Wafers available and also some sensors assembled
MALTA V2:
- Should be submitted by September
- Incorporates improvements made in the past years
- Current design 10 × 20 mm²; could re-run with 20 × 20 mm² (6-9 months)
MALTA V3:
- Supported by EP department
- MALTA V2 with larger matrix
- Part of FPGA synchronisation system will be transferred to the chip
- Serial powering (limit cabling mess)
- Should be available ~ early 2022
Substrate material choice => cluster size: hit interpolation possible
Modules:
- Part of Petra's WP
- Possibility of merging adjacent chips data: achieved with 2 chips already, possible also with 4 chips in a row
- PhD student to start in October on a multi-MALTA module
- (PR) Try existing modules and profit from existing designs
- 1 year scale to produce a module
Cooling:
- Possibility to etch cooling channels on MALTA sensor directly: works well (Alesandro M., EPFL); maybe not necessary for us
Readout:
- Control via an FPGA
- MALTA chip <-> Digital back-end ASIC (data aggregator, application/experiment specific)
- PicoTDC could be interesting for us (EP-ESE) <-> VC707 <-> GBT <-> VC709

Other applications:

Readout rate:

Sensor -> periphery max of 100-200 MHz/cm²(chamber available for testing if needed)
/!\ current back-end (VC707 / PicoTDC) can't handle this; need to find a back-end system able to cope with this rate

Data processing:

2 applications for the BGV instrument:
- Offline: detailed emittance growth studies during LHC ramp
- Online: real time beam profile monitoring => part of the reconstruction will have to be done in the FPGA (at least cluster reconstruction) to have enough zero suppression

Summary and plans:

The sensor specifications seem to be a good fit for the BGV instrument; no showstopper identified. // The BGV would be an interesting beam monitoring application for the chip.
BGV team: implement a simulation with a 2 × 2 cm²tile arrangement
Possibility to get hands on experience in build. 301 lab to try out the sensor, or take back to Prevessin
Meet up again in mid-September (Helene will send the invitation, inviting Carlos, Valerio, Heinz, Andreas + BGV team)