Building a working cloud chamber, part 4.

Sigh...the end of the semester cannot come soon enough for me.

Homework piles upon presentation upon paper...great undulating waves of responsibility threatening to swamp me. Thankfully, I gave my presentation for Partial Differential Equations today, and it went off fine (pretty good, considering I finished assembling it an hour before and practiced not at all). Now only a few assignments remain before a breather next weekend in preparation for the four finals I have the week after that.

One of those assignments is the presenting of our cloud chamber experiment on Tuesday for our last Modern Physics class. Today we ran our cloud chamber experiment for the 4th time, with, unfortunately, depressingly null results. We we quite confident of seeing something this time, especially since one of the professors graciously loaned us a sample of uranium to use as a particle source (I've never gotten to hold real uranium before!). We got a cloud just fine, but were unable to register more than a few, questionable, tracks. We decided to flip the assembly upside down again, in order to get a less turbulent cloud, which worked, somewhat. We were able to get a cloud....it was just very thin, and didn't really show trails.  So...I think the fact that we have the setup right means we'll do fine as far as grading goes (this experiment is 15% of our grade, if I remember correctly), but it's slightly disappointing not to have been able to get irrefutable particle tracks.

Anyway, yesterday I discovered by accident that Google has finally updated the satellite imagery of my home in California (after only, what, 5 or 6 years?). In fact, I was able to see the very hut I built for my ducks a year ago. It was slightly surreal, and left me dumbfounded that something I built with my own hands could be visible FROM SPACE (to be fair, I didn't build it by myself [Dad deserves a fair share of credit], but it was my idea and pet project).

Thankfully I remain in good health overall, just harried by assignments nipping at my heels as the semester draws to a close. I don't know how much I'll be able to write in the next two weeks, but I'll try to post a short something or other to keep you all informed of how I'm doing.

Building a working cloud chamber, part 3.

Once again, things are never dull around here. Yesterday Joe, our new housemate, went to the Wailuku river and found a Jackson's Chameleon in the back of a riverside cave where it had no reason to be. He brought it back, and I got some really cool pictures. Those things are amazing. 

Samuel L. the Jackson's Chameleon

Where to begin with this incredible little animal? The eyes that swivel independently? The tongue mechanism so excellently designed for catching insects? The remarkable color-changing ability? The prehensile tail and powerful gripping claws? It's just absolutely astonishing to see one up close (for the record, Jackson's Chameleons, like all chameleons, are native to Africa, not Hawai`i). And Sam is a rather large specimen, probably a good 7-8 inches from horn tip to tail. He reminds me a lot of a dinosaur from the Triceratops genus.

We also ran our cloud chamber experiment again yesterday, and finally, some results! With an old slide projector to provide a powerful light source and a modified bicycle pump to provide a vacuum, we managed to produce a thick cloud almost as soon as we had the setup complete. Now, the experiment was not 100% successful because of one fact: we were unable to catch a particle trail on camera. The reason for this is because our radiation source seems to be a dud. We did see several streaks that we believe to be cosmic ray tracks (high-speed particles from outer space that shower the earth), but nary a track did we see coming from our americium. This happening left us fairly puzzled, as americium is supposed to put out copious amounts of alpha particles (helium nuclei). Scratching the surface of the americium to remove any possible coating had no effect, so we were left scratching our heads and had to conclude that our radiation source was either a fraud, or else that we really don't know what to look for. I'd like to get ahold of a Geiger-counter and independently verify its radioactivity, but in the meantime we'll see if we can borrow a radioactive sample from the school (one of the professors has a lump of uranium he offered to lend us).
Still, seeing cosmic ray tracks (if that is indeed what they were) is pretty cool. These are high-speed (~99% of the speed of light) protons and electrons that travel through space, and constantly shower down on the earth. We saw one every couple of minutes, on average.

I should log off and get some sleep soon, but I thought I'd mention the interesting coincidences surrounding our house at the moment. I've already related my computer troubles, but I neglected to mention that Jonathan's laptop suddenly refused to turn on about a day after mine started having trouble, and the fact that John's laptop's power cord actually caught fire two days ago, leaving him without a computer as well. Thankfully, I can still use my new computer well enough if it manages to avoid locking up while starting up, and I have my old computer as well, so between me and Josh we've been able to provide internet access for them so far. So, coincidence? Or some electro-magnetic anomaly plaguing our house? As the saying goes, once is chance, twice is coincidence, but three times...three times makes you wonder...

Building a working cloud chamber, part 2.

Today was a rather busy day for me. I and my partners in Modern Physics met again today to try and get our cloud chamber project working. It was a rather mixed session. Initially, we had high hopes, as we had corrected several of the problems that plagued our first generation attempts. However, despite doing everything right that we could think of, we were still unable to see even the faintest wisp of cloud. After repeated attempts, we were about to give up in frustration and think about finding another project altogether, when I suggested for lack of any better idea that we invert the setup to have the heat source on the bottom and the dry ice on top, to create conditions more in line with the earth's hydrological cycle. Lo and behold, almost immediately after flipping everything over and applying a slight vacuum we observed some extremely faint clouds. However, this success was tempered by the fact that the clouds were too faint to actually observe any particle tracks, even after repeated attempts fiddling with various parameters.
We finally stopped again after a while, with several more ideas for improvements and the fact that we had managed to observe something. I'm attaching a humorous picture of our setup below; let me stress that the vapor in the picture is not the cloud we saw, it's from some dry ice I put in the container to create a nice visual effect. We never saw anywhere near that much cloud from the alcohol.

It's the intrepid radiation-carrying Lego man of science!

Yes, that's our radiation source that he's carrying on his head. It fits perfectly into Lego-sized openings, so we used a Lego man to hold it up and keep us from losing it. What you actually see is just the aluminum casing, the americium is only exposed in a tiny portion on the very top.

My classmate whose apartment we were running the experiment at lives right on the beach, and I actually saw a whale breaching while I was there. It was out in the ocean a couple hundred meters offshore, just expelling a huge cloud of water vapor (a lot more cloud than we ever saw in our experiment!).

Doing my latest round of complex analysis homework today, I had some really mixed feelings. Now that I've reached this point in the semester, I know enough theorems and propositions to actually accomplish some impressive things. I'm struck by how often a really complicated looking integral can be evaluated very simply, and turn out to be quite easy in the end. It's taken two months to get to this point, two months of building the scaffolding theorem by theorem, problem by problem, with little (up to this point) to show for it, so it's nice to finally be able to really do stuff.

Trying to build a working cloud chamber, first try.

As promised, here is a report of the rest of my day yesterday. After classes were done, I got together with two of my classmates to try to build a working cloud chamber for our project for Modern Physics.
If you're interested in how to do it, here's the setup we used: We took a Styrofoam cooler and cut off the bottom so that it would fit nested inside the top. We then filled the bottom with dry ice, and stuck a customized aluminum baseplate with a rim on top of that (aluminum makes the awfullest noise when placed in direct contact with dry ice as it cools to the −109.3 °F temperature of the ice. Sort of a screechy metallic shriek). On top of the aluminum, we placed our radiation source, an americium pellet from a cannibalized smoke detector. [Side note: I just did a little research on americium, and wow, I knew americium was highly radioactive, but I didn't know it was 3.5 times as active as radium. Or that it emitted gamma rays. I thought it was mostly relatively benign alpha particles (helium nuclei). I will keep that in mind when we run the experiment again...]
Anyway, after that, we placed a plastic container to be the actual cloud chamber upside-down on top of the aluminum plate. The container had strips of felt that had been wetted with 99% pure isopropl alcohol stuck to its bottom, which became the top of the chamber when it was inverted. On top of that, we placed a hot water bottle.
Since a picture is worth a thousand words, here you go:

 In this picture you can see our setup: Styrofoam cooler, aluminum plate (with handles), plastic container, hot water bottle, and americium pellet in the very middle (actually, it wasn't a pure americium pellet, it's really an aluminum casing with only a tiny spot of americium showing). The light was there for illumination.

I should probably explain the principle behind a cloud chamber, for those of you who aren't familiar with it. In theory, the hot water bottle pressed against the felt-soaked isopropl alcohol would cause it to evaporate, whereupon it would cool and sink towards the bottom of the chamber. At the bottom, it would be much cooler because of the dry ice just beneath the chamber floor. The alcohol would enter a supersaturated state, forming a cloud such that the slightest nudge from equilibrium would trigger condensation into tiny droplets. The alpha particles emitted by the americium, which are really just doubly-ionized helium nuclei, would provide such a trigger, allowing us to watch where individual atomic nuclei are going. Which is pretty amazing when you stop to think about it.

Now, after having told you all this, I hate to break it to you that our experiment didn't work because we were unable to initiate the formation of a cloud. We have several theories, which I won't bore you with, as to why it didn't work, but the upshot is that we just don't know. Apart from that, we discovered a few other hurdles with our setup, all of which simply gives us more to tweak and tinker with as we try to get it going. When we do, rest assured you shall have pictures.

On the lighthearted side, we had a little dry ice left over after the experiment, so to amuse myself I had fun dropping little bits into any standing water I could find around the house. Doing so made me thirsty, so I indulged in some of the official drink of mad scientists everywhere:

  (Pellets of dry ice in blue Mountain Dew makes a most refreshing cold beverage)