Summary 2/3/20

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  • No significant changes in design since ERR
  • Action item: steps towards assembly and commissioning:
  • Check and document interference for all kinematics again including those for the DVCS experiment from Hall A
  • dDocument time estimates for configuration changes, e.g. moving the NPS from one side to the other, rotating the magnet
  • Identify and document items that can be done in advance of installation, e.g. welding the plates on the SHMS (requires finishing the drawings)


  • Magnet was energized to 25% (250A) of the max current
  • Simulations have shown that for DVCS/pi0 it would be sufficient to energize the magnet to 2/3 of the max current - this allows to relax the requirements for a full current test. However, note that for RCS need the full field to deflect electrons
  • Running at lower current also has an impact on the HMS optics design
  • Action Items:
  • Check measurements vs 3D calculations
  • Make table of fringe fields vs. current and check simulations for physics impact
  • Decide on what fraction of maximum current to run the magnet for first run group – will also impact HMS optics


  • Final design
  • support structure has been built
  • new shielding design was adapted
  • no change in cooling strategy
  • PMT assembly concept ready (see a prototype here)
  • attachment PMT-crystal through optical grease - some rotation is possible, note that it is important to check alignment from the front during installation
  • Parts manufacturing
  • Large fraction has been received or is expected to arrive in mid-February; some delay in parts related to new shielding strategy, but still expect delivery of frame by August 2020
  • Optical fibers: 28mm diameter quartz fiber
  • Cut and polishing will be done in Orsay
  • Check uniformity of transmittance
  • Carbon holders
  • radiation hardness was tested in Hall C

Additional Notes by Charles Hyde

•Summarize full to-do list in hall, and estimated time to completion
•Estimate time for configuration changes during beam running
•Document interferences between NPS, BeamLine, HMS
•Kinematic configurations are dynamic (addition of beam time from E12-06-114, uncertain beam energy in 2022)
• How is the Calorimeter, Cabling, etc assembled
•Do we run Sweep Magnet at full power or ~30%?
•DVCS, pi0 maybe OK at 30% power
•Future RCS will require full power (with NPS on outer side of SHMS)
• Do we mix-and-match Crytur and SICCAS crystals?
•Order ~200 more crystals from Crytur and wait ~1year for full delivery?