Minutes BWS Upgrade: Electro-Mechanical Design Meeting #29 -- 14th May 2018 --

Participants: R. Veness, F. Roncarolo, J. Emery, P. Andersson, D. Gudkov, W. Andreazza, J.L. Sirvent

Agenda (https://indico.cern.ch/event/729280/)

1. Mechanics Production (W.Andreazza)

  • Missing some viewports and metallic discs, but ready to start assembly this week.
  • Viewport status: 25 ordered, for 6 instruments. Should be at CERN. Backup in case of problem: Install 2 instead of 4 viewports. Jose says this is a backup option.
  • No decision now, but watch the delivery schedule.
  • William: Series calibration of instruments should be ready to start in October.
  • What wire to use? Ray reports briefly on the work of Alex. Alex will present this when he comes back.
  • We will baseline the 34 um strand for installation. Will work on the other alternatives in the mean time. The fatigue testing was done with this single strand, so it has done 60k+ cycles.
  • Stepped chamber: Meeting with vacuum on cleaning the stepped chamber. Issue probably comes from the EB welding of the viewport stubs. Think there is a solution

2. Electronics:

2.1 Resolver (J.Emery)

  • Issue with the larger resolver (PSB and PS type), phase shift, more dramatic in the PS due to longer cables. Filter and also change phase with passive components. Could be implemented in the TS or before. Additional issue that electronics are in a more sensitive mode due to phase shift - this has been compensated in the new electronics. This would mean there is a parameter that would change the phase depending on the location or instrument to be added to the software.
  • We could operate it now, but would prefer to wait until June. However, this will not allow us to find other problems, such as the caption wire problem.
  • Agreed to order the final quantity of the rotors (Jonathan). He confirms that they are interchangeable. In principle, we don’t need to change the rotor in the PS proto.
  • Put a PSB-type resolver in the PS to look for difference in noise. Could not see significant difference between the two, so it looks like the cable length.
  • No significant difference due to 2D and 3D forged material (slide with tests).
  • New TTE Jose Maria. He will soon start to order components for storage. This is the milestone for May.
  • Talk about storage space for components - there is a solution.
  • Design validation on the calibration bench delayed from April to June. Missing some VFCs. When will they come? Jonathan will come back in 2 weeks with the design status.
  • Status - Technical student started 2 months ago working on the firmware to connect parts together for the test in September.
1.2 Charger (P.Andersson)
  • Charging time, initially 20s, went down to 13s, now to 8.8s with more powerful chargers. This is the time before the first scan, not between scans. Will need to test with long cables. Can put 2 inside the same box. Cost ~1 kCHF per instrument. Will look when we do tests in 867 to see what is needed..
  • Federico says would need 1.2s cycle time for the PS. For the SPS, may want to do 5 scans in 5 seconds.
  • Existing commercial system for protos is slightly more powerful but no longer produced.
  • Installed systems are not used every 1.2s.
  • Inverter production starting next week for a series of 10.
1.3 Acquisition Electronics (J.L. Sirvent)

  • PMT PSBs sent for production - in progress.
  • Mechanical housing in production (Dmitry)
  • Would like to run the acquisition as ‘scope-like’ so it can run on any machine.
  • Looking to compress the data transfer and aim for 6~7s for a scan.
  • Need a board for signal conditioning and to protect the VFC board. This would be in the VME crate, before VFC board.
  • Only have 2xVFCs available, need 3 for the full acquisition system, in principle just for the pre-series tests. Federico reports on discussed with Rhodri about using 3 VFCs for the series.
  • Need to discuss with Steven Jackson about the software implementation

3. Metallic disk

3.1 Update from J.L. Sirvent

  • VDL-6061. Good after machining, but damaged with craters after engraving and cleaning twice with iso-alcohol. Holes 2-5 um.
  • Was the disc in the PSB also damaged? Seems some sign of more counts from calibration to use in the tunnel.
  • LT-ultra 905 not seen any sign of degradation, even after cleaning. After 2 weeks in air and 9 days storage in dry N2, no sign of degradation.
3.2 Update from D.Gudkov

  • Cheapest offer was from LT-ultra, but not yet had a full-size engraved disc.
  • 2 suggested corrosion paths, condensation or cleaning. CERN cleaning uses 9.4 pH, which is too aggressive. RSA905 material is also more corrosion resistant than 6061.
  • SEM analysis of the slits from LaserTec. Some visible defects in the 6061 raw material.
  • Suggest making same pieces that would be tested in different environments to look for corrosion.
  • Suggests storing the assembled WS under N2 until we have further info on the instrument.
  • LaserTec engraving is scheduled for next week.
  • 12-14 weeks delivery. This is governed by the raw material and semi-product process.
  • Then we would need to make the engraving with lasertec, so another 2 weeks.
  • Agreed we will unblock the order, but Dmitry will make a hold point with the contract so they will not machine until we give the green light.
  • Will test the piece from LaserTec.

4. AOB

  • Cables (Jonathan). There may be an additional cost for removal of cables for the operational instruments. Linear scanners will be moved, but there will be a DEC for LSS4. Jonathan will not use the LIU code.
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