Wednesday, June 30, 2010

I got to see a Ti:Sapphire beam!!

  I've spend the last two days almost completely in the laboratory, which is absolutely fine by me. Bianca and I found that the two pinholes which had been used to align our system were of slightly different heights, and also that the He-Ne we were using to align everything was a little unstable in its holder. The latter problem is not so easily fixed, but we realigned everything, and have 2 pinholes at the end of our system now which are definitely at the right height. Today, Lei and I got (for the very first time) the beam we're going to be performing experiments with, and aligned it with the system. We also got a photodiode and oscilloscope and found that the chopper is quick enough to pick off one pulse. Rod's going to help us measure our pulse duration tomorrow morning. We still need to insert the lenses and the CCD camera, and also to measure beam width, but it feels like progress is being made.

  In my spare time, I've been reading a paper by W. Lamb about a QM treatment of the photoelectric effect without the use of photons. Essentially he treated the electric field of the incident light classically and the metal in a quantum fashion, simplified to one dimension, applied perturbation theory, solved for the photoelectron density matrix elements, and re-derived Einstein's equation (E=hv-W). I understand his approach, although he skipped quite a few steps in the derivation, so his math was difficult to follow.  The paper can be found as the 8th footnote on the wiki page about the photoelectric effect.

  I played badminton last night. I played pretty poorly, which might be related to lack of sleep during the previous night (I have a hard time sleeping when it's hot and it has been hot and humid the last few days. Thankfully, last night and today are better). I need to get in better form before going back to school. My backhand is failing something awful. Everybody here plays with plastic birdies, which are much less responsive than feathered birdies. By less responsive, I mean that more force is needed for a similar change in momentum. The upshot is that shots I think should be going just over the net are hitting it halfway between the tape and bottom.

 I intended to renew my Navigo last night and forgot. I need to do it tonight or else tomorrow morning is going to be hellacious.

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