I give up on science for tonight so let me tell you how much every single step can fail in experiments sometimes.

How my experiment failed 

So my problem is: I am measuring the absorption spectrum of some material, and I have an unidentified peak which where there should be none according to 60-years-old litterature.
But they also say that sometimes some forbidden modes become allowed under certains conditions that I didn't understand, because uh, symmetry and stuff.

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How my experiment failed 

It happens that my spectrometer has also a cryogenic chamber, so I'm thinking that if it's a phonon, it should evolve in some recognizable way with the temperature.

Still waiting from a confirmation from my professor about if that's a good idea, but that's only two days, he probably didn't read my email yet.

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How my experiment failed 

First problem, nobody used the spectrometer with the cryo chamber since a year, and I think I even told someone it was ok to move away the supports in which the chamber can be attached in the setup.
:oh_no:

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How my experiment failed 

The setup is in a box, with a small hole and a lid above where the sample goes, and if I stick the chamber in the hole, then I can't put my hands inside to attach the feet or change the height :oh_no:

Of course there is no reference or anything, not for the position of the chamber, not for the height of the feet.

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How my experiment failed 

And each time I move the (maybe 5kg) chamber in and out (within the limits of how far away the vacuum pipes let me move, and they kept making knots somehow), I was bumping into the optics inside the spectrometers and misaligning everything.

The lenses inside where supposed to be screwed tight but they were coming loose :oh_no:

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How my experiment failed 

It took a few hours to find a position and height about correct for the chamber, I had a lot of signal coming through, and then I realized: too much signal.

Well with all this turning upside-down and up and down and up and down and shaking, the crystal glued inside had fallen :oh_no:

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How my experiment failed 

Thankfully the crystal didn't get lost in inaccessible parts of the chamber and it didn't break, I just glued it back and waited for the night.

Comes today! I think everything is ready and I go fetch liquid nitrogen in another building.

Spoiler: everything was not ready.

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How my experiment failed 

I noticed I was missing the temperature monitor, which is somewhat important when I want to measure something with respect to the temperature.

I'm doing without vacuum monitor though, it disappeared since last time :flan_shrug:

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How my experiment failed 

Temperature monitor is easy, I have one, but I don't have the computer on which I have a python script to record what the temperature was at a certain time (my very first python script from before learning python). Found it, but then python is broken on it, and then matplotlib doesn't want to let itself be installed, and then somehow the script crashes.
Buuut I repair it by just removing the plot parts.

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How my experiment failed 

Everything good, time to measure the spectrum at room temperature!

Except that with the additional losses from going through the vacuum chamber, my signal-to-noise ratio was lower, and my magnon frequency was lost in the noise.

:oh_no:

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How my experiment failed 

So I redid the steps from yesterday, pulling to chamber out, pushing it in, adjusting the height of each of its 3 feets, until I have 8% more signal and I can see some signal above the noise at the frequency I'm interested in, if I average long enough.

I time the length of a measurement because a "100s integration" of course doesn't mean that the measurements takes 100s, so I can calculate what the average temperature was while it cools down during a measurement.

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How my experiment failed 

Also, I found the perfect position and I don't want to remove the chamber to attach the feet before putting it in and hope it goes back at the same place, so the chamber can move around if anything touches it. Or its vibrating vacuum pipes.

The temperature sensor shows an error, that's supposed to be normal when it's above tje temperature it can measure, and I think I remember it's normal.

So I slowly pour liquid nitrogen in the chamber and wait to see it go down…

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How my experiment failed 

And I'll keep a cliffhanger here because I arrived at my sports class :blobcatgiggle:

Such science much suspence!

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How my experiment failed 

So, the chamber cooling down!
I'm only pouring small quantities of liquid nitrogen at a time, so I have time to take 100s-long measurements without the temperature changing too much.
And I wait for a number instead of an error to appear on the readout. I'm not sure which sensor is inside, but I don't remember that the highest measurable temperature was particularly low.

Except nothing appears.

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How my experiment failed 

I end up filling the chamber and I'm pretty sure it arrived at the lowest possible temperature (77K or about -200Β°C, the nitrogen boiling temperature), but still nothing on the readout.

The cable between the sensor and the readout are always homemade because not every sensor works the same sobwe had to solder cables on the right pins, but I'm pretty sure the cable was the right one since it was just lying there. And it's the only one there.

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How my experiment failed 

For some reason the "temperature not in range" error on the readout also happens when there is no cable plugged in. And now that I think about it, I'm not sure I even saw a temperature sensor inside the chamber when I glued my sample in.

(My glue is nail polish, if you even wonder.)

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How my experiment failed 

And that's how I ended up figuring out how to put together a windows batch script to move the mouse over the "save" button and click every 20min.

I had recorded the temperature while another chamber was heating back up last year so I know approximately how the temperature will evolve overnight while everything warms up again. If I correlate that to the spectrum saved automatically, I could see if my phonon at least seems tenperature-dependant.

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How my experiment failed 

Now I'm halfway certain that by tomorrow, the unshielded electronics which is our humidity sensor in the spectrometer will catch some random electric field (inside a box with a THz laser running? How weird :thinking: ) and make the computer reboot as it does at least once per week, and I will come back to no data and be frustrated and maybe just wait for my professor to answer whether that will even help identifying the absorption peak or not.

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And this, dear brave people who didn't mute the thread yet, is another normal day in a laser lab :chick_cry_happy:

(Usually it's just months-long experiments so less funny to talk about.)

How's everyone day going, what is going all wrong when you try to do stuff? :blobcat:

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