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The pulse tubes are really loud. We've wrapped the helium lines in sound absorbing foam, and we have a cage around the top of the cryostat also lined with foam, but it's still pretty loud.

To make this an interesting physics question I ask: how is the sound getting from the mechanism to my ears? Does the sound travel through the support frame? Through the helium lines?

Given the transduction channel, is there an effective way to reduce the noise?

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    $\begingroup$ I am curious if any of the close voters know anything about experimental cryogenic systems? The usual set of meta posts apply: meta.physics.stackexchange.com/q/5553 meta.physics.stackexchange.com/q/2948 and meta.physics.stackexchange.com/a/4146/520. $\endgroup$ – dmckee Sep 13 '14 at 20:37
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    $\begingroup$ To be sure the question makes no particular reference to an experimental context, which may have something to do with people's decisions. I would just plead for a little more time taken on such decisions. $\endgroup$ – dmckee Sep 13 '14 at 21:23
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    $\begingroup$ @innisfree: Yes, it is about soundproofing a particular specialized type of equipment used only by experimental physicists. Suppose I were to ask about how to stabilize a laser; would that be accepted here? Given the links provided above by dmckee, I think closing this question doesn't make sense. $\endgroup$ – DanielSank Sep 13 '14 at 21:30
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    $\begingroup$ @innisfree: I tried an Area 51 proposal for a dedicated low temperature physics site, but several folks are complaining that the types of questions proposed for it really should be asked here. I think a lot of people agree with this as evidenced by the existence of the experimental-technology tag! "Physics" does not mean "parts of physics which don't actually involve building things." The implied definition of "physics" expressed by voting to close this and similarly oriented questions is a constant source of displeasure for experimentalists. That should be enough of a reason to not close it. $\endgroup$ – DanielSank Sep 13 '14 at 21:41
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    $\begingroup$ I think this should not be closed, since it is pretty clearly about experimental physics - but I don't feel it would be appropriate for me to unilaterally reopen it. If a few other people did so first, I would definitely vote to reopen. In the meantime I wonder if another meta post would help matters... $\endgroup$ – David Z Sep 13 '14 at 23:32
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I'm afraid we've found no real solution to this problem. I think the noise propagates through the support frame, and sound proofing doesn't help very much. I think your best bet is either noise cancelling headphones or remote desktop as much as possible. But neither solution will help other people who may be in the same lab.

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  • $\begingroup$ Did you guys try anything to isolate compressor hardware from the fridge itself? $\endgroup$ – DanielSank Sep 26 '14 at 22:15
  • $\begingroup$ The compressor can be a long way from the fridge (up to 100 ft on a BlueFors fridge, I believe) and the still pump can likewise be fairly distant. They can be electrically and mechanically isolated in the same way you would isolate any pump. But I remember asking OI about the pulse tubes and they gave the impression there was nothing to be done. $\endgroup$ – NLambert Sep 26 '14 at 22:38
  • $\begingroup$ What I meant was that you can mount the remote head so that it's not mechanically connected to the stand holding up the cryostat. We did that by attaching it to the ceiling near the fridge. $\endgroup$ – DanielSank Sep 26 '14 at 22:47
  • $\begingroup$ I just had a look at our fridge and I see what you mean. We haven't tried that, but we have no more room above the frame to do so. Interesting suggestion though. $\endgroup$ – NLambert Sep 28 '14 at 12:32

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