Maintenance for BNMR-Oxford Cryostat

Sept 19:

• Upgrade started, cryostat vented.

• Hole selector wheel disassembled and reassembled (we thought there was a thermometer in it. There is not. 

Sept 20:

• Cleaned some fine metallic dust under the RF coil. 

• Copper RF coax disconnected from RF coil, removed. Antenna also removed.

Sept 23: 

• Unmounted the sample thermometers. While bent, the right thermometer (as seen from the beam) survived. Verified with DVM. The left thermometer broke and is in need of replacement. 

• Thermometry labelling appears to be backwards on the cryostat. Rahim’s notes from 2002-2005 on muquip suggest that they are inverted. The broken one, based on Rahim’s notes, is GaAlAs 10540. 

• Silver braided coax (for backscatter plate?) removed. It was not connected to anything. 

• Confirmed that Rahim's notes from muquip are accurate: 

  • Connection Label: “Kapton Heater”: https://muquip.triumf.ca/sites/default/files//maintenance_files/12037169...

  • Connection Label: “Oxford Header”:
    https://muquip.triumf.ca/sites/default/files//maintenance_files/12037180...

  • Note that the heater on the Kapton heater side (connection i-j) is 156 Ohms, corroborated by BNQR logbook 12, page 40 (2014).

Sept 26:

• New flexible, kapton-shielded coax installed. Product info:
  Manufacturer: Accu-Glass Products, Inc.
  Kapton insulated TYP6, 26 AWG, 50 Ohm coaxial cable, male on both ends. 
  Part number: 110755
  Max. Operating Temperature: 250ºC
  Max. Vacuum Level: 1x10E-10 Torr
  Contact Material: Cu alloy, Au-plt
  Materials: PEEK, Kapton, Cu-Au-plt
  https://www.accuglassproducts.com/coaxial-sma/connector-cable-sma-male

• Coax connections to dirty side finger tight. Gaskets replaced, sealed. 

• Verified that thermometry circuit is unharmed with DVM. 

Sept 27 - 30:

• Coax ends stripped with scalpel. All center conductors intact, verified with microscope.

• About 1mm of braid trimmed from end of coax to expose kapton dielectric. 

• Made new copper antenna.