LHC Has Collided Protons at 7 TeV!!!

Read the posting here.

If you're wondering how colliders work, ArsTechnica put up a great article this week on how they work.

As a freshman at Michigan State University, my family and I had the pleasure of being able to take one of their periodic public tours of the Cyclotron facilities. One of my favorite parts was how they curved the acceleration path at one point to separate particles by mass, so they could then sort of collect particles in Faraday Cups at the end of the path. That a machine so complex and powerful replies on the fundamental principle of inertia to sort the subjects of its studies by mass is somehow poetic.

Turns out we use that exact principle for isotope detection, except that it's on a far smaller scale. My research group makes frequent use of a multicollector induced-coupled plasma mass spectrometer (MC-ICP-MS), which allows us to measure with a high degree of precision (when the machine's behaving; I swear it's sentient sometimes) isotopic ratios. In particular, I'm looking at stable (or non-radioactive) iron isotopes. In the future, I'll be looking at stable magnesium isotopes, (obviously unstable) uranium isotopes, and possibly stable silicon isotopes. Silicon's difficult because of its low solubility in most solutions and its tendency to fractionate.

Fractionation occurs when some mechanism allows the preferential movement of one isotope over another. I'm being vague on that definition for a reason; there are multiple ways in which this can happen. One example is heating the sample to a level where silicon melts and could possibly vaporize. Heavier isotopes require more energy to lift, just as lifting a car requires more energy than lifting a bicycle. If there is only enough energy in a system to vaporize a few silicon atoms at a time, it's much more probable that the lighter silicon atoms will vaporize.

It doesn't exclude the possibility of vaporizing the heavy silicon atoms at this time - it's just less probable. However, if more energy is introduced to the system, the probability of heavier silicon isotopes being vaporized increases greatly. Were I to analyze collected silicon vapor collected from each of the energy levels, I'd find that the lower energy vapor has a "lighter" signature, whereas the higher energy vapor has a "heavier" signature.

Recall, though, that this is only one way to fractionate stable isotopes. It's by far the most common process, but there is also chemical fractionation. I won't go into as much detail about this process as I'm less familiar with it, but it's definitely a fascinating study and I'm hoping we go into great detail about it in my isotopes class next fall.

Why silicon is being problematic isn't clear yet. Part of our chemical procedure to prepare samples for analysis hasn't been perfected yet, and we know that for sure. One particular chemical added in extremely small amounts is intended to "anchor" the silicon in solution so it doesn't form a colloid or precipitate out, trapped in telltale wispy flakes that settle at the bottom of the sample tube. Too much of this chemical and it will occupy all available site on the silicon atoms in solution and turn into a gas, which means it will fractionate out an eventually escape. Dilution of the sample beyond the theoretical minimum volume required to dissolve the amount of silicon present hasn't entirely helped, either.

But the best part by far is that mass spectrometry and photospectrometry of the samples have provided results exactly the opposite of each other (there should be at least a rough direct correlation between the two). Hard to say. We're still working on the method.

And on that note, I should head into work fairly soon. My first class of the day was delayed by half an hour, but I have an array of small tasks I should plow through in some capacity before then.

Smoke Rings!!

Hello from Champaign!

. . . Disregarding the fact that I've had a place to live here since June, I AM making my first post from the U of I.

This place is REALLY nice. The style of the campus is reminiscent of (a better-tied-together-architecturally) MSU, with a slightly smaller campus surrounding a series of quads. The building I'm already busy at work in backs up to the main quad, which means it's REALLY easy to find a place to hang out on breaks (and honestly, I haven't spent much time sitting still there . . . I've mostly walked or jogged through it).

I've been working in my building since mid-July and have already ventured into the field once. I have a sample set to prep already (which I'm REALLY happy about!), and though I may well find myself back in one of the calderas, sampling more of the particular ignimbrites (material erupted out of a caldera) I'm interested in before too much longer. However we DO have enough at the moment to get some preliminary results to look off of. I'm ambitious enough to attempt analysis of a minimum two isotope systems in the near future. Before any of that happens, I do have more work ahead of me:

1. Currently, I've been placed in the lab with one of the undergrads who's been working here for a while. He's helping develop analysis methods for a certain isotope system that is present in nearly every rock (in fact, not aware of a rock that does not contain the element with said isotopes of interest) - mostly grunt work, which I'm more than happy to have a hand in, especially given it's been invaluable while learning my way around the labs I'll soon be living in.

2. Prepping SEM (Scanning Electron Microscope) mounts happens tomorrow. I've refrained from this part of my project till now to ensure that I can have someone in lab with me so I can make sure I'm familiar with the proper care and handling of the U of I Rock Saws, let alone what sort of cut is needed for a good SEM mount. I'd rather not have an accident like the one I had at MSU. While there were only superficial injuries (and not to me) as a result of that incident, it scared several people and new safety measures were taken as a direct result. I've also been slightly skittish of rock saws since. Didn't help that the substitute saw we used in lieu of the broken saw (took somewhere near a month to fix) had a failing motor and rougher blade, which resulted in jagged slices and a few slammed thumbs. (And no, I definitely do not hold anyone responsible for this. Accidents happen in labs and that's just something an empirical scientist has to accept and in turn know how to mitigate as needed.)

3. Learning my way around the mass spectrometer is a big one. I know the principles upon which several incarnations of mass spec operate, but that's entirely different than knowing how to actually RUN one. I can at least test samples for voltage ranges and adjust them accordingly. I've also been shown how to calibrate the machine to get proper isotope readings - this is significantly more involved than a simple voltage test and it will definitely be a while before I know this procedure well enough to run solo.

4. Next week's TA training and classes starting soon after. Not sure if I'm more nervous for some of the training activities or teaching my first real class. Yipe. Why are they so willing to trust dozens of people's college educations to ME?!?!

(I'll get over it. The worst part and sometimes the best is the anticipation. Sort of like the 30 seconds right before the call to attention and Kickstep sequence in the tunnel of Spartan Stadium.)

Then, of course, the rock wall and I made friends before dinner this evening. Totally worth it and totally hoping that I can stop by enough to become a regular. The collaboration between climber and belayer, obvious end goal, and variables such as palm sweat (HAVE to find a solution for that) and forearm fatigue combines for some interesting resistance training that I'd like to exploit. That combined with the cardio (if I can ever get my lazy arse back onto a regular running schedule) would have some great physical results. I only did about 2.5 climbs over the course of about an hour and a half and I feel really good.

The social aspect is important. I feel like I sort of failed that part of my undergrad, because I spent my time with only two groups and one or two other people whom I've known for a long time. While I'm hanging out with mostly folks I knew last summer from field camp, I've felt more at ease meeting people here. The mentality's a bit different from SE and Mid-Michigan and I like it.

And on that note, it's probably well past shower-time. I still smell like I've been rock climbing. : )