General Meeting Summary 6/14/18

MAGNET ASSEMBLY PLAN (Bogdan)

• Discussion about details of assembly

• Largest parts assembled in test lab, total assembly may be done in another location and full magnet transported back to test lab
• Total weight is ~10t

• Need a ~1-page document specifying tests/mapping of the magnet - check in with Charles

HV BASES (Julie)

• Have received about half of the boards, ready to assemble

• Have 1000 sockets at OU, still need the remaining ones

• How many sockets are at JLab? Vladimir checked into this:

• 36 old type sockets (machined one) in C124 office
• 149 old type at Fernando`s laboratory F117 that sockets already mounted to HV divider circuit boards
• 15 have been sent to Julie

• So it is 200 total plus

• 120 new type sockets in NPS cleanroom with PMT`s

• In the end we got 320 sockets at Jlab

• 35 PMTs will come from OU to JLab

• Action Item: Send link to location where to store information on bases, data sheets etc. (Tanja)

CRYSTALS PROCUREMENT (Tanja, Rolf, all)

• Discussion about path forward - procure fewer crystals from Crytur (bid was higher pricing), procure 580 crystals from SICCAS (instead of Crytur), or a mix of 400 from SICCAS and 100 from Crytur

• Good to check quality of Crytur crystals over a large sample - so far have only checked in single digits for rectangular crystals
• Need to have all NPS/Hall D crystals over next few years
• Discussion about combining crystals from different vendors in calorimeter
• Crytur is not willing to provide crystals at less than $1900/piece at this time (original discussion was $1300/piece), Giessen U. negotiations unsuccessful
• SICCAS is willing to replace crystals and discuss procedure to meet specifications

• Decision to check if possible to procure 400 crystals from SICCAS and 100 crystals from Crytur. If not possible, will proceed with 580 crystals from SICCAS

NPS PROTOTYPE/COMCAL (Vladimir/Alexander)

• Ongoing main activities

• PMT testing - set of 200 Hamamatsu R4125 PMTs being analyzed
• Engineering drawings
• Assembly location details - 126, TEDF?
• Crystal wrapping and storage
• Monitoring system

• PMT tests suggest good performance overall, but see relatively large fluctuations in distribution of PMT amplitudes though all within 20%, in actual experiment will gain match

• Reflector to be used: ESR (same as VM2000 discussed in January 2018 NPS meeting by IPNO team)

• Need sheets 17"x17" to cover 140 crystals, thickness 5um
• Procedure for pre-shaping: anneal at about 100 degC
• Test wrapping with dummy bar made of either stainless steel (better thermal expansion coefficient) or aluminum (easier to work with). Note error of machining is ~100 um

• Next steps:

• Systematic checks of PMTs
• Update documentation of PMT tests - also link to NPS Wiki

• Current location is in Hall D Wiki (for those with access: https://halldweb.jlab.org/wiki-private/index.php/PMT_testing)

• Will present more details of test and assembly status in next meeting

NEXT MEETING: THURSDAY, JULY 12, AT 9:00 AM (EDT)