PREX/CREX Apr 9, 2019 10:00am

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Logistic information

 BlueJeans calling instructions:
 Toll-Free Number (U.S.&  Canada):  888-240-2560
 International toll number:         408-740-7256
 Bluejeans CODE:                  628 981 532
 Bluejeans link:
 Offline room:   CEBAF Center F326-327


  1. Installation progress: Ciprian docDB363
    • SAMs:
      • KP: have we looked at the SAMs? DM: we just installed them for now with good preAmps and PMTs. We just checked that they are functional. We still have the cable problem that we are following up with Jack. We will double check the light tightness.
      • KP: can we summarize what is installed? DA: we already made a haplog entry 3705.
      • DM: we will install the shutters for the SAMs in a month or so.
  2. Optics: Ryan Optics Ryan
    • RR: we have a zero day position and plan to do a scan for commissioning.
    • RR: we have a set of optimized Quad pol tip values. It is not exactly perfect but it is getting closer.
    • RR: we are investigating a proper way to implement fringe fields.
    • RR: working on a unified CAD model as a high priority for the installation
    • SR: the CAD model for the left arm is going to be on an analogous rail, but it will be much tighter
  3. Optics: Seamus
    • SR: met with Kando and Siyu and they will get things ready to for Jack and installation.
    • SR: we have the inventory for the cabling and mounting.
    • SR: we have everything shipped;
    • SR: the optics and software: have everything from prex1 and old GEM code. We’ll start with the SBS offline that was modified for the SLAC test. I’ll coordinate with Bob and put everything on a repository in GitHub. There is a bit of coding that would be new for using both VDCs and GEMs, but it should not be a large amount of work.
    • SR: started drafting optics run procedures.
    • SR: will get in touch with APEX folks for the latest VDC calibrations.
  4. GEMs: Chandan slides
    • ChG: we had a problem with the GEM4 board. Fixed by connecting to the neighboring channel.
    • SR: we don’t need to run at 600Hz with 6 samples. We will run with Gigabit ethernet and 1 crate so we need to adjust.
    • SR: depending on how we implement 0-supression there could be efficiency problems that could pop out. The 3 samples should be sufficient two handle the multiplicity in the GEMs.
  5. Discussion for next week:
    • SAM installation: Devi
    • Adam: Compton polarimeter


In F326

Sanghwa P, Dave G, Ciprian G, Caryn P, Jay B, Tao Y, Ye T, Eric K,


Adam Z, Cameron C, Chandan G, Devi A, Guido U, Jinlong Z, Juan Carlos C, Paul K, Paul S, Rich H, Robert R, Ryan R, Seamus R, Victoria O, Dustin M, Kent P, KK, Siyy J,

Cannot make it

Bob M,