Minutes of the bi-weekly POLAR-2 meeting of December 2nd 2019

Agenda:
- News from discussion with CSU
- Technical design report update Geneva
- Technical design report update Poland
- Irradiation test plan
- Spectrometer discussion (Jianchao)

Attendance:
- Geneva: Nicolas dA, Nicolas P, Xin, Merlin
- IHEP: Jianchao
- MPE: J. Michael, Jochen
- NCBJ: Agnieszka

News from discussion with CSU:
- Merlin: We got answers about 5 questions, they are given on slack. These are preliminary answers (through wechat), we will have to wait for the proper answers through email
- Jianchao: For the data download commanding we need to provide CSU with a proper document explaining what we need
- Merlin: We should at some point (not a priority now) also plan a simulation of this procedure with them
- Nicolas: Agrees we need a proper discussion on this, not a priority now
- Nicolas: 28V reply does not make sense
- Merlin: We can wait a bit more for the proper replies from them, if not by the end of this week I will push for this
- Xin: Did we get the CAD files from them?
- Merlin: Not yet, but also Franck has not yet sent ours to them, Franck will do that this week, these drawings contain the maximum size that fits through the door


TDR discussions:
- Dominik not here today, will provide his part of the TDR in the coming days
- WP1 and WP2 have been added to the old "TDR" started by Nicolas and Merlin, Merlin just added these two structured parts to the document will do more clean-up of the rest in the coming days
- Document is on svn
- Nicolas will put instructions on slack for those who do not yet have access to svn on how to get this

Optical simulations for scintillator design:
- Merlin presents slides on scintillator design optimization for POLAR-2
- Tapering on both sides will be changed, used to be down to 5 mm, now will be 5.4 mm. The # optical photons / keV is expected to be 4.4, in POLAR this was 2.2. Gives an expected threshold of 2 keV.
- Merlin and Jianchao will check if there is vikuiti at the top of the bars
- Xin suggests to check if the top of the bar can be coated to improve things, Merlin will check (this can be done with real bars instead of with simulations)
- Final step for the design is to get the optimum length of the bars, requires simulations with the full POLAR-2 setup, Merlin will try to do those this week
- Grid design can now be finalized by Franck

Irradiation test plan:
- Dominik sent an idea to collaborate with a group in Poland to do irradiation tests of SiPMs
- Agnieszka suggests to wait for Dominik to be there for further discussions, however, it is clear that this group has experience and it would help to do this together instead of doing this alone at for example Bern.
- All components need to be tested during next year, so we should start planning

Spectrometer discussion:
- Not much to discus now, we wait for answers from CSU and from Franck
- J. Michael will give some numbers to check if the 'wok' is feasible within the mass budget.

AOB:
- Dates for the meeting in Munich are now fixed