Mar 20, 2018

Link to all previous meetings: Weekly GMn GEM Commissioning Meeting

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 Bogdan, Evaristo, Kondo, Leo, Nilanga, Roberto, Siyu

Status of the INFN GEM Cosmic Stand

Roberto gave a detailed update on the setup of the cosmic stand for the INFN GEM layers

• 3 chambers fully instrumented on the cosmic stand (Jo, J1 and J2), all 12 modules are holding HV very well, (nominal 4 kV with Ar-CO2 75/25). One of J2 module that previously had issues (See Evaristo's talk at SBS Coll Meeting Feb. 2018) with HV was also fixed (basically the modules had to be cured over time to burn dusts etc ...)

• FE cards: Mostly all APV25 cards and back planes on the 3 layers (12 modules) have been tested and are working properly except for a few (3 or 4) cards that for now are been masked. One back plane is also not responding properly, at the moment is also masked
• DAQ: Main issue is with the DAQ / MPD modules / VME crate. A lot of problems running the system in a stable way even at a very low trigger rate. Roberto and Leo experience full buffer issue when taking data. Seems like some slots in the VME crates are causing the problem. 5 out of 12 of these slots with MPDs had been identified as the source of the problem. There seems to be a pattern with the every two consecutive slots of the crate are OK while the following two are instable. The team is investigating the problem with the help of Alexandre who also works on the CODA codes to try to debug and fixes some related problems
• Leo and Roberto are trying to identify 8 stables VME slots to be able to operate 8MPDs to fully read out 2 out 3 GEM layers and start taking cosmic data. They would probably have a clear idea of the situation later today. The priority is to be able to start taking cosmic data in a stable fashion so that we can start characterizing the INFN GEM modules. The DAQ issue should be handle in parallel and would require more experts to take a look at (Alexandre, Danning, Paolo etc ... depending of their availability)
• Gas bottle: Currently one Ar-CO2 75/25 gas bottle in use, we should always have one spare bottle available during the cosmic data taking (see with Bogdan / Mark how to proceed with this). Also we need have N2 gas bottle available
• Trigger: Setup is operational, currently less than 1 Hz trigger rate, can be optimized, we should expect a few hertz not a priority for this week. In addition, one of the scintillator bar of the bottom trigger layer is not operational. We will replace it (discuss wit Bogdan this afternoon about this).

Status of the UVa GEM Cosmic Stand

• They receive the new longer screws, will prepare them (cleaning etc ...) for assembly.
• Will put the mock chamber together once more this week to check if gas leak issue is fixed with the longer screws