Minutes BWS Upgrade: Electro-Mechanical Design Meeting #15 -- 10th October 2016 --

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

Agenda( https://indico.cern.ch/event/569140/)

1. Progress on preparation and test of PSB prototypes:

1.1 Mechanics (D.Gudkov)
  • Prototype Test program aims to schedule tests for:
    • 3 Prototypes: 1x PSB, 1x Laboratory + Tank, 1 x Test-Bench with no tank
    • PSB prototype ready for vacuum qualification
  • PSB Installation procedure tested on laboratory
    • Successful installation in <5min
    • Requires the usage of a crate + 2 people
  • Optical Disk status
    • Glass disk + Glass sample ordered
    • Holder for glass disk ready for production
    • New metal samples to study with electrochemical polishing (25 samples AW-2219 + 25 samples AW-6082)
    • Electrochemical polishing tests with SS under preparation.
  • Scintillator + Filter Box + PMT Assembly:
    • Design ready 97%
    • Drawings are in CCD: PS_BWSA_0067 .. PS_BWSA_092
    • Filter wheel designed by CERN and fabricated by Thorlabs
    • 10 Units confirmed (2 with higher priority)
1.2 Acquisition (J.L. Sirvent)
  • Filter wheel design:
    • Updated design with Thorlabs standard filter holders & Opto-Sigma ND filters
    • 8 holes with SM30.5 thread
    • Components for 3 filter wheels have been ordered
  • Optical encoder glass disk design:
    • Selba is able to fabricate the disk with our required diameters (internal 70.2mm & external 192mm)
    • Design has 2 tracks 20 & 40 um pitch (50% Cr. 50% Glass), and alignment references.
    • 20um pitch: 32.0 +- 1.6 um resolution
    • 40um pitch: 66.7 -+ 1.7um resolution
    • 5 Disk ordered with 3-4 weeks delivery
    • Available 7-11 Nov 2016.
  • Optical sensors potential design improvement shown:
    • Requires 2 new optical components in vacuum: 1 concave lens & 1 index grating 20um pitch
    • Robustness to disk imperfections (Scratches, planarity...)
    • Scan point ~ 500um-1mm diameter.
    • Trade-off --> Quite sensitive to alignment
    • W. Andrezza: Not possible to get the required tolerances mounting components on viewport.
    • If metal disk is base-line this could be a potential help, If we continue with glass we can still rely on system as it is.
  • Photo Multiplier tests:
    • Optical bench prepared for testing: Dark box, ND Filters, Led & pulsed Laser, iris, holders...
    • Tests: Linearity, Saturation, Dynamic range
    • Systems to test: PMT R9880-U, MaPMT R7600U -01-M4, HPD PP0475C
    • Different strategies for high dynamic range coverage under study.
  • PSB YETS installation:
    • Base line is only Standard PMT assembly + Custom MaPMT assembly
    • If MaPMT is tested with ICECALV3, we may install digital electronics (unlikely on YETS).

1.3 Control tests of the PSB Prototypes (J.Emery)
  • Discussion prior to presentation:
    • Tests done on prototype: was it possible to move and reach nominal scans?
      • It was checked if the ball bearings load changes with scans speed (tests performed at different constant speeds).
      • Motor showed to behave as specifications.
    • Many concerns regarding pre-loaded ceramics ball bearings :
      • The load of the ball bearing is much bigger than the break nominal design.
      • This type of bearings are used for maintaining high precision.
      • Required to know what precision we're getting and also to know tolerance (Standard & pre-loaded Ceramics)
      • Bigger clearance = easier to move but more mechanical play...
      • Standard clearance ball bearings already bought for being installed.
      • Proposed to check difference between these two types by testing with the calibration bench.
      • 1 BWS with Standard + 1 BWS with Ceramics will be prepared for testing.
  • From presentation:
    • Unstable scan profiles because of issue with resolver.
      • Trying to decouple feedback loops to regulate correctly
      • Not nice profiles in terms of speed.
    • Issue with the new resolver type:
      • Signal shown is much weaker than previous type.
      • Comparison done with PSB Proto (RO5032-452 SN:9026) VS Unmounted Rotasyn (RO5032-452 SN:9027)--> PSB proto shows 1/2 weaker signal (unknown reason: bigger gap?)
      • Same effect when compared with SPS proto
      • Better signal digitalization provided by electronics developed ("intelligent drive") than Dspace system.
    • Ball Bearings tests:
      • Scanner rotating at different constant speeds
      • Torque has not linear behaviour with speed (3Nm @ nominal speed introduced by bearings)
      • Clear behaviour difference respect motor TB
      • Break design done for 0.5 Nm at top maximum force.
      • Break would need to be re-designed and re-scaled for these ball bearings in order to provide it's functionality
        • Material would need to be changed
        • Break re-scaled (much longer).
    • Current stabilization requires more study

2. Plan for series production: Milestones for mechanics (W.Andreazza)

  • Design completed at end 2016 (including PSB,PS & SPS integration studies)
  • Same kinematic unit for all instruments except fork (different lengths)
  • Each machine needs its specific tank (for integration reasons).
  • Some feedback missing from TE/VSC and BE/RF for design finalization.
  • Design status (Smart design to minimise the # of variants):
    • PS 90%
    • PSB Pre-study based & design start in October (V. mounting).
    • SPS Information and location known Integration study will start Oct/Nov.
    • BI Goal: Manufacturing drawings ready for procurement Jan 2017.
  • Procurement and fabrication:
    • Critical material procurement done by BE/BI
    • Order needs to be placed Easter 2017 for delivery in 12 months (2nd Q 2018).
  • BWS ready for installation 1rst Q 2019

3. AOB

  • In PSB the existing scanners will be kept once the new ones are installed.
  • The most accurate scanners are the slow linear LHC and SPS scanners.
  • Is it possible to use the SPS rotary at lower speeds? (performance needs to be checked in this cases)
  • Need to get information from calibration bench (end 2016)
    • Try to get measurements of repeatability + accuracy
    • Also needed to check wire stress at nominal speeds PSB.
  • Concerns about # of calibration benches:
    • Proposed to have 2 or 3 benches for parallel commissioning/testing.
    • Possible always to provide holders for BWS (no tanks) in order to simplify installation.
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