Summary 2/1/19

ACTION ITEMS

List of Action Items for ERR

SUMMARY NOTES

INTRODUCTION - ACTION ITEMS AND ERR (Tanja)

• For ERR in general need a list of outstanding scope and how/who will address it

• Discussion based on action item 2018 list in slides:

• page 1 items:

• Need an installation plan (Walter, Steve L. and team...)
• demonstrate that design complete and floor layout plan exists
• show what scope of work remains and who will do it
• show that fringe fields under control

• page 2 items:

• cabling - show that there is a plan how cables go on carriage

• page 3 items:

• what to show for software, DAQ, and electronics...

MAGNET UPDATE (Charles)

• Assembly done, ready for power and cooling - in test lab will get to 20% of power due to cooling limitations

• no need to power up before ERR
• plan to power up in summer

• June might be good time as tech teams should have more time then
• need to have estimate of fringe fields for magnet test area

• might want to check modeling magnet with and without base plate (concern is additional magnetic material) - might be ok with 20% energizing

• Mapper is ready for magnet tests

• need to start on safety documentation - J. Beaufait, E. Folts can help
• mapping plan is expected to be developed in first half of February - idea is to run without field and devise plan based on that

• Fringe fields

• show that no impact on beamline magnets - earlier studies showed that no impact, but might want to check again
• for ERR mainly need to show that have a plan

FRAME (Emmanuel)

• Design mostly ready - main question is who will do assembly

• Impact of cross talk in neighboring modules

• Ho-San measured 0.5% of light (from regular showers) goes from one to next crystal - expect same for LED

• Check on vertical clearance for PCB interface box - there may be interference with SHMS water lines

• For PMTs and electronics interface, need to know smallest signal size that still needs to be digitized

• Discussion crystal-PMT attachment and crystal array design

• Assume that silicone cookie will stick to either crystal or PMT when removing PMT
• Crystal array assembly is new - using aveoles (material only at first ~2cm along block, everywhere else along block 0.3mm air between crystals). Just put crystal inside, no compression.

• NOTE: to quantify shower leakage could run simulation and make shower profile with and without gaps

• Survey requirements

• standard is survey to 1mm on fiducial block on outside of frame
• For Hall A DVCS surveyed all block locations. Note that calorimeter was at 1m from target, so mm offset results in 1mrad
• calibration with e-p elastics possible? Need to check if can adjust calorimeter (in x, y, z) for these kinematics - in principle can do that with screw adjustments or shims

CRYSTALS (Vladimir)

• Discussion on crystal quality and tests

• Measured 2%/sqrtE with 3x3 prototype as expected given limitations of instrument - essentially have 8 edge crystals
• For NPS 12x12 prototype tests used temperature sensors on front and back of crystals

• Action Item: Make a spectrum of photon energy for crystals next to the one hit - should address question about smallest signal digitization - estimate is 2-3% of energy of hit crystal

• Saturation fADC - nominal voltage for linear range is 1100 V for HV divider, but this saturates. In Hall D tests ran with 650 V

• Rates comparable to NPS (250 kHz/channel)
• threshold >2 GeV overall (10-15mV/channel)