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.