Gianluca: Not actual mintues, I just summarize from top of my head. Please correct/add if something is missing.
Mike:
- From Geant4 simulation it shows that currently, a modification of Twin GEM-TPC not needed for first tests since improvement for MIXE only small
- He/CO2 (90/10) gas mixture would be necessary for good performance/resolution
- Francisco: Unsure if triple GEM will work with such mixture, not been tested. Will need to figure out if triple GEM were already operated with such gas
- For even better performance, underpressure GEM-TPC would be an option
- Francisco: Not possible with this prototype, but could be done with thick GEM
- Quite some scattering on muon counter scintillator, therefore having an idea of angle of track needed -> Twin GEM-TPC for now, later single GEM-TPC with timepix readout to reduce length
Francisco:
- Calibration setup based on scint. fibers needs to be build. Necessary to measure actual drift time depending on HV set (details in uploaded presentation)
- Mike: Will take care of 3D-printing structure and SiPM based readout
- Gianluca: Best to be ready by 10.05. with that, so it can be tested with muons at PSI before beamtime starts. Need to see how to share muon test beam with other experiments (DOLLY).
- Francisco: For test beam at CERN not needed, can use reference detectors.
- Will move prototype to CERN in March (mid-March). In principle everything ready. SRS and amount of VMM chips sufficient if only half of active area of GEM-TPC is used
- Mike: Okay with MIXE, since beam spot is small (~2cm sigma) compared to total active area of GEM-TPC (~20cm). Can also work with just 10cm.
- Paolo: A few chips and another SRS crate (no DVMM card though) could be available from NA64 for tests in case
General questions:
- Is there space for us in RD51 lab to make some first tests with the GEM-TPC (leak checks, radioactive source for checking signals & VMM)
- Mainly Mike & Benjamin (+Francisco, Gianluca), if needed also help from others of MIXE team
- Is it possible to use He/CO2 already in RD51 labs? If yes, what would need to be prepared beforehand (e.g. drawing new gas line from outside, ordering bottle, flowmeters?)
- Was He/CO2 90/10 already used with triple GEMs, are there any optimal/limits for voltages known?
- ...
Next meeting: around 10.03.2023
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