Minutes BWS Upgrade: Electro-Mechanical Design Meeting #12 -- 13th July 2016 --

Participants: Raymond Veness, Bernd Dehning, Federico Roncarolo, Jonathan Emery, Patrik Andersson, Jose Luis Sirvent

Agenda ( https://indico.cern.ch/event/543918/)

1. Communications (R.Veness)

  • PSB ECR already launched and progressing on the aproval
  • Forks 2-3 units are out of tolerances. The work has to be redone, which would delay the pieces availability to end of August.
  • For mounting test (on august) 1 of these fork will be modiffied to fix the tolerances with some bricolage.
  • The error comes from a perpendicularity deviation Shaft-Fork.
  • The assembly test will be performed in August and the device plans to be available for functional testing on September.

2. Alxion Standard and Special Motor testing (J. Emery)

  • Tested Alxion Standard and Special version with modiffied airgap (300V)
  • Back-EMF normal version: Show nice results and 1% deviation respect to specs
  • Back-EMF special version: Show also nice reults with 4% deviation respect to "estimated" specs.
  • Not clear if special version was tested by Alxion before procuring specifications or they approximated by calculations
  • Speed and profiles tests with Special Alxion show satisfactory results with Dspace, calculated torke ~ real required torke
  • Problem found after motor testing:
    • Appeared after the week-end (test finished Friday, problem appeared Monday)
    • Motor generates a extrange noise even when not moving and holding position
    • Effect is not symetrical, appears in In & Out Scans but seems stronger in Out scans.
    • Currently trying to work out the reason:
      • During movement the currents are showing a extrange behaviour
      • Motor dismounted, visual inspection (Dmitry) show no frictions
      • Isolation on phases seems not to be the problem, tests show that they're ok.
      • Cross-Check wiht Parker motor--> No problem seen
      • Test with older compiled code --> Problem still seen
      • Generator Mode --> the output voltages are Ok
    • Next steps:
      • Try standar Alxion
      • Try another Alxion stator 300v
      • try standar rotor.
    • For the moment the reason still unclear.

3. PSB Acquisition system: Intallation proposal (J.L. Sirvent)

  • Installation requirements: 1 Functional system (PSB standard) + 1 Test flexible test platform (Independent systems)
  • Base line is acquisition on surface , both options send their analog signals to surface
    • In PSB short cables & long bunches --> Fine for BW point of view (bunch pile-up)
    • Gain in noise reduction << Risk of failure of acquisition Front-End for radiation exposure
    • In any case allow installation of a Front-End for testing pourposes
  • The idea is to procure a operational (PSB) system 100% available for functional validation
  • Allow space & cabling flexibility to test different scintillator + photo-detector configurations
    • Standard Cylindrical 30x30mm
    • New Rectangular 100x100x10mm
    • MaPMT, HPD, Filterweels
    • Space reservation for 1 Front-End
  • 3 Set-up Configuratoins show using the same cabling requirements.
  • High dynamic range acquisition system (no required filter / pmt gain tuning)
    • Strategy 1. HPD + QIE10/12 (1e5)
    • Stregety 2. MaPMT + ICECAL (1e5)
    • Stragety 3. MaPMT + 2 x QIE10/12 (1e7?)
  • New mechanics required to procure for both assembies:
    • FilterWeels
    • PMT/MaPMT/HPD shielding
    • Scintillator/Waveghides holder
    • Supports
    • All these details are not included on ECR
  • Studies on PSB needed to:
    • Estimate required dynamic range on PSB
    • Adjust acquisition systems working point
    • Cross-Check PSB simulations
    • Check possible improvements by changing Scintillator Geometry
    • Check Light yields on scintillator per impacting proton on wire (for different energies/intensities)
  • Proposed ways to proceed:
    • Trust on simulations ? Check with Roberto Rocca.
    • Estimate light yield trough measurements stored on measurements DB
    • Prepare measurement campaign new systems when installed.

4. Comments from Dundee Visit (R.Veness)

  • Some issues were identiffied thanks to the visit
  • Residual material observed on measurements:
    • It reduced the reflectivity on some disk areas
    • Comes from some abrasive liquid used for finishing the laser slits.
  • Smooth transition Reflective/Non Reflective
    • Such smotth transition did not allow enought "flat" reflective area between slits
    • Sample and laser are in a fix position, Laser scans the disk by angular movements
    • Laser loses focal point, which produces wider slits
  • For Dundee Equipment, 20 um width slits was already on the limit (we asked for 10um slits)
  • The fabrication of full size disk would produce worst slits due to equipment configuration
  • Dundee required XY Stage + Controller system (and maybe new laser) to produce high quality slits.
    • Estimated Cost > 10KCHF
    • In collaboration with other sections and other uses foreseen, if required cost may be splitted by 3.
    • Jose's remarks:
      • With commercial company we reach the results required for the slits.
      • Does it worth it? we'd need a guarantee that this new equipment would produce better slits than commercial.
      • In any case, the sensor weak point is the surface quality (roughness, defects, reflectivity)
      • Instead of spending time/money in building very spensive disk it may worth it to improve the sensor robustness with some minor mofifications for metallic disks usage (more scaning dots / different configuration).
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