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v3.3.2-pre
Minutes POLAR-2 Bi-Weekly meeting December 16th 2019
Attendance:
Geneva: Nicolas P, Nicolas dA, Merlin
NCBJ: Dominik
IHEP: Jianchao, Hancheng
MPE: J. Michael, (Jochen for post meeting)
Merlin: Update Geneva on scintillator simulations:
- Updated the POLAR-2 simulations software + first data analysis programs, will be placed on Github this week
- Performed simulations of the signal + background using POLAR-2 and POLAR software to optimize scintillator length
- Optimum length found now is short: 75 mm, however, the minimum was not found yet (only went down to 75 mm)
- Needs some double checked, especially if changing the background incoming distributions have a large effect on this
- Taking M100 into account (or "figure of merit" as suggested by Jianchao) will likely push for shorter bars as well
- Nicolas: we should find the minimum first, if it is clearly very short we should go down to ~100 mm
- Merlin will continue the studies this week also checking for further off-axis angles
Nicolas dA: Update on SiPMs + scintillator design
- Preforming calibration of the SiPMs (from MPE) to find the IV curve at different temperatures
- Tested almost all, curves look good and values correspond to those given by Hamamatsu
- Went from -40 to +40 C, all SiPMs behave well
- Produit: we see from these plots that power supply for the SiPMs should be able to give ~1 mA (a few microA per channel).
- Figured we can use fully rectangular bars, requires optimization of the plastic grid
- First design done, will be send to cern in the coming days for production
- CERN can print things with a thickness below 100 micron, so with the current design we can use rectangular bars with a thickness of 5.9 mm (significantly better than the 5.4 used in POLAR)
Dominik: Update from Poland
- Was busy over the last weeks, will now work on the TDR, is using the template from svn
- For irradiation tests we have to discus with the group at NCBJ, they will have heavy ion tests in first half of next year, not sure about protons
- Merlin will send an email to start planning
- Produit + Dominik: need to produce some simple firmware specifically for irradiation tests of the GOWIN FPGA, will check in the coming weeks
J. Michael:
- Did not have time to look into the requirements for the Wok, will check in the coming days
- Jcohen did find some old BGO from GBM which can be used to play with
Jianchao:
- Will finish a funding application from IHEP on wednesday to apply for spectrometer production + data centre at IHEP
- Merlin clarifies that it is not planned to have the main data centre at IHEP, ideally data comes from CSU directly to Europe
- Jianchao clarifies that money for some computing facilities is needed anyway, no matter if IHEP takes the data directly from CSU or gets it from Europe.
- No official news yet about funding application with Yoni Granot, but quite clear they will receive the money for POLAR analayis, POLAR-2 studies + eXTP
(connection with Jianchao broke)
Post meeting Jochen + Merlin:
- Some money now exists to build some prototypes of the scintillators
- Ideally Jochen buys crystals with some SiPMs already mounted, Merlin will check for a BabyMIND board which we can lend to MPE
- Plan would that Merlin + Nicolas dA come for a week to help startup the readout of the crystal to check if the FEE of the polarimeter is suitable for spectrometer