Technical Board Meeting July 10, 2023

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Technical Board Meeting June 12, 2023 << >> Technical Board Meeting Sept 11, 2023

Online: see email

Agenda

  • TM4 Production Coil (Mike Dion) [pptx]
  • Description of grounding scheme for Main Dectectors (Michael Gericke) (Using materials from docdb:1133 )

Minutes

Spare TM4 coil - Spares are included in the contract for the production of DST coils for TM1, 2 and 3, but not for 4. A plan for a Change Request for a space TM4 coil is under consideration.

  • Original contract with EMI for DST coils included 8 of each type. Later modified for 2 spares each of TM1-3, but no spares of TM4.
  • If one of the seven TM4 coils were to be damaged, this could create significant delay. The issue is primarily schedule risk vs budget risk.
  • Damage could occur during production (vendor responsibility but MOLLER still suffer the delay), shipping, or installation.
  • A prototype for TM4 exists, but it is not clear if it is a usable spare
    • This prototype may mitigate schedule risk, but may introduce technical risk.
    • A report on the TM4 Prototype is available (now posted here: docdb:1149 )
    • to the best recollection of anyone on the call, the TM4 prototype is geometrically identical to the production coils
    • There are some concerns with de-lamination, but unclear how important those are
    • Measurements show significantly more deviation of coil vs epoxy surface (that is, position variation of inner coil
    • Additional evaluation from physics side needed to evaluate technical risk using the coil.
    • Similarly, the spectrometer group should evaluate the technical risk including any concerns with mechanical stability or geometric compliance (de-lamination, bulging, etc.)
  • Cost vs schedule risk
    • cost to wind spare ~ 10k$. This would be 1.5-2x more expensive if performed later.
    • EMI is not only set up now, but they have learned from previous production - knowledge which may be lost if production of a spare is needed later.
    • cost for additional g10, about $10k. Potting also still required.
    • time to acquire g10: 10-12 wks (for jlab. vecdor has been working with a 20 wks leadtime on g10.)
    • winding a spare (to take advantage of existing expertise and tooling) but deferring additional g10 and potting until needed is thought to be a reasonable cost for risk reduction
  • Some discussion about how stable the coil condition is after winding, before potting
    • The coils are produced with a fiberglass wrapping.
    • Surface oxidation may present a problem. Some oxidation is unavoidable, but this group did not know whether this surface if passivated by the oxide or whether degradation continues
    • The conditions for storage are not known. At least dry and maybe low oxygen environment might be perferrable.
    • A fixture for maintaining the magnet geometry may also be needed for stored magnets.
    • N.B. this is a potential Q.A. consideration for all magnets, which are stored 10 weeksor more after winding before potting. Currently under investigation.
  • Spectrometer group and physics side need to evaluate technical concerns with prototype TM4, to balance technical risk for this option vs schedule risk.
  • After that evaluation, this subject can be revisited. There are at least several weeks before the vendor will complete TM4 winding, so there is still time to make this decision.
  • It will be determined at a future time whether further discussion in the TB is needed.

Detector Grounding The proposed grounding scheme for the main detectors (designed to control noise due to ground loops) is shown. Isolated low-voltage power supplies for the pre-amplifiers, based on this design, will soon be ordered.

  • Differential signal from detector pre-amp to ADC, with no ground reference.
  • ADC planned to recieve an isolated ground. It may be powered by a grounded power supply (Power-over-Ethernet is particularly convenient, and is not necessarily or not expected to be ground-isolated.)
  • Similar systems have worked for previous experiments, and for recent prototype tests, with low noise.
  • Safety grounds for enclosures are also employed.
  • Safety is evaluating now, but there aren't expected to be problems based on past usage. It is noted that isolated power supplies are used elsewhere (for example, in magnet power supplies).

Attendance

  • Kent Paschke, Chair (MOLLER Scientific Coordinator)
  • Krishna Kumar (MOLLER Spokesperson)
  • Jim Fast (DOE Project Manager)
  • Michael Gericke (MOLLER-CFI Project Coordinator)
  • Mark Jones (Hall A Leader)
  • Robin Wines (Project Engineer)
  • David Armstrong (Elected Executive Board Member)
  • Paul A Souder (Elected Executive Board Member)
  • Carl Zorn (L2 CAM: Detectors)
  • Mike Dion (L2 CAM: Spectrometer)
  • Ciprian Gal (L2 CAM: Infrastructure)
  • Robert Michaels (L2 CAM: DAQ)
  • Vladimir Berdnikov (L2 CAM: Installation)
  • Paul King (Working Group Convener: DAQ)
  • Dustin McNulty (Working Group Convener: Integrating Detectors)

Absent:

  • Mark Pitt (Deputy Spokesperson, MOLLER-NSF Project Coordinator)
  • Nilanga Liyanage (Working Group Convener: Tracking Detectors)
  • Juliette Mammei (Executive Board International Representative)
  • Dave Meekins (L2 CAM: Target)
  • Silviu Covrig (Working Group Convener: Target)
  • Caryn Palatchi (Working Group Convener: Polarized Beam)
  • Rakitha Beminiwattha (Working Group Convener: Simulations)
  • Jim Napolitano (Working Group Convener: Polarimetry)
  • Yury Kolomensky (Working Group Convener: Physics Extraction)
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