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 (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

• 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

MECHANICAL DESIGN (Paulo, Steve L.)

• 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)

POWER AND CABLING (Joe)

• 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

DAQ AND ELECTRONICS (Brad)

• 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

TRIGGER AND ELECTRONICS (Alex C.)

• 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

NPS PROTOTYPE (Alex S.)

• 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

CONTROLS AND MONITORING (Hovanes)