Mechanical Precision Test

1
Mechanical Precision Test

• 2 mechanical measuring jigs (Al body, steel
  rails, double ball-bearings)
• tests mounts (dowel and threaded holes) to 0.05mm
• tests cylindricity and verticality at height of
  kovar ring of window to 0.1mm
• white LEDs to aid visual test procedure (0.1mm
  gap non-touching!!)

measuring edge
screws
dowels
2
Precision Test Example

• HPD size
• 83.0mm (0.0mm, -0.1mm)
• Jig size
• 83.4mm
• Teflon tape
• 0.1mm thick

point of first possible contact
gap 0.1mm
any contact failure
3
Mechanical Tests - Results

• Mechanical precision test (36 HPD tested batch
  1-3)
• 35x passed without problem
• 1x slightly misaligned dowel hole (H518006)
• fit on test jig only with some force
• just about fits into wall mount (less precision)
• no problem to fit on cup (least precision)
• (1x slightly leaning, i.e. just within tolerance)
• Socket (36 HPD tested batch 1-3)
• 4x pins bent in operation by different people
• (H441001, H516009, H524002, H524005) ? fixed

4
Visual Inspection Results I

• Threaded holes (36 HPD tested batch 1-3)
• all have holes for ?-metal 3 anodised ?
  preferred NOT anodised
• mounting holes 3 anodised (H516018, H525002,
  H539001)
• Quartz windows (36 HPD tested batch 1-3)
• all edge chamfers in Scotland optically polished
  ? as required
• at CERN
• 2x no chamfer
• (H407008, H428001)
• 6x frosted chamfer
• (H516007, H516008,
• H519001, H516010,
• H516015, H521006)

bad!!
bad!
good
5
Visual Inspection Results II

• Scratches
• 4x 1-2cm scratches found (H516020, H518003,
  H524004 (2x), H539007)
• 3x surface damage found (H518001, H518006,
  H518007)

0.5cm
2cm
H516020
H518007
6
Visual inspection Results III

• 2cm gap in Silicon
• H530001, H527007
• hole at cathode cable
• H539003, H542001
• gap in indium seal
• H530010
• side hole
• H518003