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[personal profile] lymanalpha
Hi friendslist! How are you? You've been kind of awesome. Thank you for the books and the random conversations and the WIP-viewing and just everything.

I don't have anything really exciting for you in return, but this is what I've been giggling over all week. Maybe you'll find it amusing too.



The scene: undergraduate experimental-physics course, a few years ago. We were trying to observe superconducting behavior in materials. Most things need really low temperatures to go superconducting, so part of the experiment involved making things really cold. In this case we dunked them into a dewar of liquid helium.

Helium condenses at about 4K, aka really damn cold. To keep it liquid, you need a pretty hardcore dewar, but the stuff boils off anyway. So at the start of each lab session, we'd have to check the level of helium in the dewar. We used a long tube with a membrane on the top. The membrane would kind of flutter when it hit the liquid. Then we'd just measure the tube and know how much helium was left. Boring and straightforward.

Here's a page from my lab notebook, to show you the setup:

Photobucket

The probe can go up and down, into and out of the big dewar.

OKAY BUT THEN! We had this lab manual. And the lab manual had detailed instructions on how to measure helium levels. And clearly, whoever wrote this lab manual was either the least pervy person in the history of ever, or A MOST SUBTLY AWESOME PHYSICS PERV. Witness:

The long tube was called the dipstick. Or sometimes the probe. These are direct quotes from lab manual:

"Straighten the dipstick before and after insertion. It is easily bent, so take care."

"If you feel any resistance while the probe is being inserted, remove the probe immediately. The penalty for not doing this may be sticking of delicate probe components to the neck surface."

"During insertion, jiggle the tube up and down slightly."

"A small back-and-forth twisting motion during the process eases the motion. Never apply excessive force in sliding the probe tube along the flange."

"Vertical jiggling of the dipstick may help to initiate the excitation. "

"When the probe is in the liquid, the throbbing is of low frequency and constant amplitude. "

"Once the dipstick has been lowered to the bottom, you may have trouble exciting further throbbing."

"The insert probes are delicate and must be handled with care. This means that they should not be bumped against other objects....When inserting or withdrawing the probes, keep them strictly vertical, no bending please!"

And finally:

"Always have the neck plug inserted when the dewar is not in use."

AND THEN, on the same page of the manual, there was this picture:

Photobucket

...Yeah. There was a lot of snickering that term.



Also, I was going through my old lab books and found this drawing of a radio telescope. That experiment had some long calibration procedure we had to sit through, which is why I was drawing it, I guess. Anyway. It needed more Spock.



Photobucket
The "aww, so cute" was actually written in the notebook. Spock was not.
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lymanalpha

August 2010

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