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Entry  Wed Aug 4 18:55:58 2021, aaron, DailyProgress, Cryo vacuum chamber, loading cantilevers into megastat 6x
    Reply  Thu Aug 5 14:12:36 2021, Stephen, DailyProgress, Cryo vacuum chamber, loading cantilevers into megastat (and actions toward pumping down) 
Message ID: 2634     Entry time: Wed Aug 4 18:55:58 2021     Reply to this: 2638
Author: aaron 
Type: DailyProgress 
Category: Cryo vacuum chamber 
Subject: loading cantilevers into megastat 

This afternoon I met with Aidan and Stephen about near-term plans for the megastat. Aidan and I got familiar with the various viewports, and identified that if we want to set up another window for laser access we would need to move the existing window to the viewport 60 deg clockwise from its current location (at the SE corner of the chamber). We also noted that there is a single instrument RTD currently available (plus three others monitoring each heat shield and the cold head), so setting up two separate measurements each requiring temperature readout simultaneously would require opening up the electrical feedthrough and wiring up another RTD.

This week, I will be installing a clamped cantilever into the existing op lev setup in the cryostat. We will then pumpdown the chamber on Friday, and cool down over the weekend. At the beginning of next week, I will make some Q measurements of the clamped cantilever around 123K, then warm back up so Aidan can set up PD testing at the end of next week or early the following. 

Today, I pulled a moderately smooth cantilever from cryo, and brough it over to QIL to clamp it. I hadn't used this clamp before, and found that the cantilevers Zach was producing in 2018 are larger than the slot in the clamp that was in the megastat. Since the clamping screws are not centered around the cantilever itself, one end of the clamp is touching steel on steel and the other is slightly open. I found in the elog that Zach was using a spare, broken off cantilever piece to balance the clamp. Later, he updated the clamp design and used an alignment jig to set the cantilever in the clamp. I will bring these items from cryo lab and install them in the megastat tomorrow. 


  1. clamp before any changes
  2. View of the indium foil below the clamp
  3. Two cantilevers from cryo, I used the one on the left
  4. The uneven clamping job. Following my first attempt at clamping, I opened the clamp fully and noticed (and removed) Si particulate on the clamping surfaces. This uneven clamp is damaging the cantilever, and/or the cantilever's edges are shedding.
  5. Showing that the clamped cantilever is somewhat too high for the megastat window. The cantilevers Zach was using with this clamp were shorter, and we do have some remaining in the cryo lab. 
  6. Overview of the megastat before covering with foil

Additional photos are on the ligo.wbridge google drive, under Google Photos -> CantileverQ.

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