Setback

So, I kind of screwed up. When going over the final design for my gas delivery system to JJ today, he inquired about the accuracy of one of the flowmeters we were planning on buying. The accuracy is rated at +- 5% at the maximum flow rate, which you can pay extra to reduce to +-1%. That accuracy, however, only applies to the maximum flow rate. The further you get from the maximum rate, the worse your accuracy gets. When we calculated the uncertainty at the flow rate we'd be using we got 360% for the +-5% and 76% for the +-1%... both totally and completely unacceptable. Another reason this comes out so poorly is that the resolution of these flowmeters is given in minutes and we need good resolution down to seconds. At least we caught this error before we paid $400 something for the flowmeter. That's one more lesson learned in the world of experimental physics. It's not a huge setback, but it is going to take a few days to find another flowmeter. We're currently looking at electronically controlled ones since I can't find a manual one with the resolution and flow rate that we need.

I started the application process for graduate school on Monday. I sent in the main application (name, birthday, address, etc) and applied to be a Ph.D. student in Nuclear Engineering. I've got my transcripts being mailed to them and I've gotten all the people I need to write my recommendation letters. All I have to do now is wait... Aghhh!

Something interesting about nuclear structure that I read the other day. I'm sure most of you are familiar with the 4 forces that govern what happens in our world: gravity, electromagnetic, nuclear strong, and the nuclear weak forces. The nuclear strong and weak only manifest themselves inside the nucleus, but they are many orders of magnitude more powerful than gravity or the electromagnetic forces. Here's an interesting comparison between the gravitational and electromagnetic force. If the strength of gravity could be represented by the length of my forearm, the strength of the electromagnetic force would be represented as the length of the known universe. That' BIG. Back to the nuclear forces, though...

Here's something crazy I read the other day about nuclear structure. Protons and neutrons are both fermions, which means that in a given energy level no two particles can exist in the same quantum state. Also, within the nucleus, protons and neutrons are much closer together than electrons are which means that collisions between nucleons (protons and neutrons) is a fairly likely event. If a collision occurs, energy is transferred from one particle to the next. This energy transferal would be manifest in one of the nucleons moving up to an excited state (nuclear structure theory has a shell-like model, just like atomic theory and electrons). Now consider some nucleons in the ground state and further consider that there are many filled states above ground. Since all of the states above the ground are filled, if a nucleon were to transition to a higher state it would have to be given enough energy to transition to the very last energy level (like jumping from the bottom step in a staircase to the very top in one jump). What I find wild is that if a collision between two particles would not yield enough energy for such a jump, the particles are not allowed to collide! How #$%@ing wild is that?!

Something like this also happens with superfluids. I can't remember the specifics without looking at my book (which is in Georgia >_> ), but it involves particles being unable to move to excited states because collisions would not provide enough energy (below a critical velocity, in this case). I love physics.

Flat Tire amber ale is delicious.