Summary 2/1/19

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  • Admin:
  • Make a draft agenda including action items
  • Draft COO
  • Draft prelim rad form
  • OSP magnet and detector
  • Check in with Chris Cuevas on NPS ERR
  • Schedule a date for ERR



  • 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...


  • 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 (5 probes) attached to corners, front and back of detector
  • 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
  • Action Item: send 10 crystals to IPN for irradiation test
  • 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)
  • Discussion about overall plan for crystals
  • important factor is if SICCAS can sign for 400 crystals with NPS quality - also determines is take back 145 SICCAS crystals from Hall D
  • plan to purchase more Crytur crystals - in principle could have ~600 CRYTUR by end of 2020
  • different crystal array configurations depending on how many CRYTUR crystals - in general, place SICCAS at edges where only have to catch the shower, and CRYTYUR in regions of higher radiation and where physics is (in center) - as example see Vardan/Hamlet's drawing


  • Discussion about structure tasks and completion status
  • Sweeping magnet support positions: now need to move magnet laterally, originally not - engineering design 30-40% complete
  • Beam line concept design stage
  • Cable routing - need detector design details (see talk by Emmanuel and 11/13/18 meeting and 1/31/19 meeting notes)
  • Movement of and mounting of detector
  • to move detector from right to left: crane pick up on rail piece with detector bolted to the rail
  • overall responsibility of JLab
  • information from IPNO on center of gravity and weight would be helpful
  • Action item: reinforcements to make detector as stable as possible during movement would be helpful
  • Action item: check on angle 22.5 degree requirement that now determines if NPS left of right of SHMS
  • what is the limitation?
  • previously had 30 degrees - with the smaller angle might need configuration changes within one experiment
  • Discussion about what is needed from NPS collaboration?
  • nothing yet except information about cables, i.e. cable lengths
  • First experiments will have NPS on the right side of SHMS (smaller angles, closer to the beamline)


  • Discussion about where power supply could go in the hall, e.g. where SOS one was?
  • Discussion about number and location of penetrations into SHMS for HV and signal cables
  • number of penetrations sufficient (checked in 2016), but locations may not be idea
  • make bore hole into top of SHMS?
  • Discussion about timeline, plan, decisions for cables


  • Discussion timing - NPS experiments get timing from fADC directly
  • Available number of fADCs seems ok for NPS experiments
  • Action item: need info on fADC threshold - should be >= 5mV
  • Need to decide on: 1) read everything out (this seems best) or 2) Trigger
  • Trigger on NPS and read out wave forms - coincidence rates seem manageable (presently can handle 4.5 kHz)
  • Plan for VTP readout - need to converge, tasks to be done include:
  • hardware
  • firmware and DAQ development
  • require 5 VTPs ($45k)
  • Rack space in SHMS - all can fit, but need to figure out how to get the cables in
  • HV/Slow controls
  • Action item: add temperature - need info from IPN on how many temperature sensors, channel count
  • discussion about anode current - perhaps best to estimate from fADC (done that way for prototype, good to factor 2)
  • Data rates - 20 MB/s is ok, beyond 200 MB/s requires a lot more work


  • VTP readout good option as less rate limited
  • Suggest clustered readout like done for HPS
  • coincidence data rates seem reasonable
  • Test setup plan to install in hall


  • Discussion about experience gained
  • documentation and procedures available in Wiki
  • slow controls developed: HV and environment, e.g. temperature - all information is archived
  • Ongoing studies to understand observed nonlinearity - divider performance?
  • Action item: check stability of temperature monitoring and how long it takes to stabilize
  • Plans to data additional data in spring - e.g. with fADC dynamic range set to 2 V
  • Action item: submit ideas for additional tests


  • Used EPICS 1527
  • Time required to write controls depends on which type - detector support group responsibility
  • can be very fast if build on something existing, and in particular if have hardware/motors etc.
  • HV controls took ~ 1week
  • motion controls took longer (~month)
  • environment required engineering support for sensors


  • More than half assembled - need to clarify saturation observed with prototype for path forward
  • anode current limit is 100uA
  • Action items:
  • check dividers for lower voltage range (600-700 V) - Alex S. and student might be able to help
  • check into bypassing amplifier - Fernando has a way to do that and it affects the easy to modify part of the board


  • Basic NPS geometry is ready for any simulation
  • checked background, magnetic field, dose rates
  • Next: offline software - can be based on Hall A DVCS software


  • Discussion about best options for NPS
  • A7030 HV with 36 or 48 channels - 36 might be beneficial due to grouping in frame


  • New project to produce material with luminescence properties comparable or better than crystals at much reduced cost and easier and faster to manufacture
  • Initial tests very promising
  • Prototype test planned for fall in Hall D
Action item: provide details on what is needed


  • Develop agenda based on charge - some items can be grouped
  • Design and installation plan is mandatory, also any equipment test plans as needed
  • Equipment talks - could be three if group
magnet should also include implications for beam line commissioning
  • Early radiation levels - complete a prelim radiation form and submit through Hall contact (likely Doug H.)
  • Draft charge items 2(d-f) and 7, 8, and 9 require some work
  • Action items:
  • Make a draft agenda including action items
  • Draft COO
  • Draft prelim rad form
  • OSP magnet and detector
  • Check in with Chris Cuevas on NPS ERR
  • Schedule a date for ERR