New Instrument Development at Oak Ridge National Lab

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UPDATE (1/9/2013): The SNAP Instrument team also did a synopsis of UT’s week working on the CCR! Read about it on their blog.

This last week I was up at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) working at the Spallation Neutrons and Pressure Diffractometer (SNAP)… that’s a lot of acronyms. Basically, the goal of the week was to test a new piece of equipment for doing low temperature, high pressure neutron research. This is the beamline:


The neutrons come in from the lower left, hit the sample, and then the ones that diffract at ~90˚ (±5˚) hit the detectors (the big square things to the left and right), and the rest keep going through the sample to be stopped in that big beam-stop/collimator in the back.

So why are we working on a new instrument? Why hasn’t high pressure neutron diffraction been done at low temperatures before?

Well, when we say “high pressure” what we’re trying to do is get to 15+ GPa range. Which basically means the pressures of the Earth’s mantle. Currently there are cells available for neutron diffraction at cold temperatures that can do up to about ~10 GPa, and it is possible to use a Diamond Anvil Cell (DAC) to do the pressures/temperatures in the range we’re interested in using synchrotron x-rays. But using the DAC system with neutrons is tricky: it’s a lot harder to “see” only your sample as opposed to the diamond.


In the middle there (in the shadow) are two diamonds. Basically is works like this: imagine the diamond on an engagement ring… now flip it upside down so the pointy end is up, now polish the tip down so you get a little flat platform that’s ~200-1200µm in diameter. Now still a sample on that tip, and cover with another diamond you did the same thing to. Now press them both together using a lot of force. That’s how a DAC works.

Now, with x-rays it’s easy to shoot the photons through the diamond, hitting the sample, and then coming out through the diamond on the other side without too much interference. It’s also easier to make teeny-tiny x-ray beams so that you can aim the beam at only what you want to see. With neutrons, the beam can’t get as small as easily and it “sees” more of the DAC, causing a lot of interference.

Another problem is you have to cool the whole thing down. And the more material you’re cooling, the harder it is to control and the longer it takes to cool. In order to press on the DAC, we have to stick it in this:


That’s a lot of steal to cool down.

When it’s all in place, the sample and DAC are connected to a chilling element that goes down to 4˚K (liquid Helium temperature), but the rest of the contraption is connected to a chilling element that only goes down to 77˚K (liquid Nitrogen temperature). And it looks like this:

Malcolm and Afu discussing possible future improvements of the design.

Installing the device into the vacuum pressure can (we have to cool it down in high vacuum or the water in the air will freeze onto all the electronic equipment and make things go haywire):


There are many improvements to be made (the temperatures for this first try were higher than we would have liked, and the pressures lower than we would have liked), but this is a great first stab at opening up this area of science. It helps to have a great team:

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From left-to-right that’s me, Malcolm Guthrie of Carnegie Institute of Washington, Junjie Wu from Geophysics at the University of Texas (UT). Junjie’s supervisor, Jung-Fu “Afu” Lin, was also there:

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Afu recently received tenure here at UT, so congrats to him!

We also worked with the SNAP beamline team who were amazing and incredibly hospitable. So many thanks to Chris Tulk, Jaimie Molaison and Antonio Moreira de Santo!


Austin Marathon: T-9 Weeks Recap

So, last week was a little off for the training. That’ll happen when six days are on the road. Would have been nice to get at least north of 20 miles on the week, but that just didn’t work out.

Two runs on the treadmill:

And this one.

And then I got a great little 7ish miler in actually around the Oak Ridge National Lab campus:

This week has also started off slow… need to get back at it before and during the Christmas break!

Update: Oh! I really like my new shoes:


Austin Marathon: T-10 Weeks Recap

Back to it! Had a great week of running. Almost 40 miles on the week and ending with the Decker Challenge.

I started with two shorter runs on Monday and Tuesday evening. I should have made at least one of them a 6+ miler, but I was just trying to make sure I got myself in a good groove for the week so I didn’t want to push it:

I almost didn’t go on Wednesday. But I got some late evening inspiration and went out for more than 8:

Rounded out the week with a nice Friday evening run before taking Saturday off before Decker:

Race day was pretty awesome. I went into it expecting nothing: just planning on treating it like a training run. That’s because it’s notoriously hilly, the weather was supposed to be (and was!) really humid and muggy, and I had been training all week (as opposed to tapering for the race). I was really pleasantly surprised with the outcome:

Nothing like setting a Half Marathon PR on a tough course on a less-than-ideal weather day. I felt great all day and ran negative splits (faster second half–7:15 min/miles–than first half–7:37 min/miles).

I started with the 1:40:00 pace group, figuring I’d drop off the back after a while (my previous PR was 1:41:17, so I wasn’t expecting to hang with them the whole time). But since I was feeling good, I decided to move in front of them to avoid the tight clustering in the pack… I ended up dropping them and getting a 4 minute PR: 1:37:17 official chip time.

Makes me feel much more confident for the marathon!

Here are the results highlights: 54th of 1032 Overall, 6th of 47 in Age Group (M 25-29), 52nd of 501 in Gender. Not a bad day.

So You’re Thinking About Grad School, Part 2: Tips for Writing a Proposal

Pro Tip 1: Do not start your NSF proposal a week and a half before it’s due… especially when that week and a half includes needing to work with the administrative departments at three large organizations… and especially when that week and a half includes Thanksgiving break when all those administrative departments like to be home, you know, eating turkey… and especially when that week and a half includes your Fiancé flying into town for four days.

Pro Tip 2: When you ignore “Pro Tip 1,” be working with amazing people on said proposal.

Pro Tip 3: Invest in coffee.

You may have been wondering where all the updates on this blog have been. And then you used your keen eye and highly trained critical reasoning skills to read between the lines of my Pro Tip 1 and deduced: Luke has been busy.

In my defense for doing the unthinkable of pulling together an NSF Proposal in just over a week (Pro Tip 4: Allow yourself a couple months for this under normal circumstances), I was unaware of this Fellowship until about two weeks before its due date when I got the heads up from the professor I’ll end up working with on this project (if we get it). Luckily, I followed my Pro Tip 2, because between her and my other potential mentor for this project I was fortunate to be working with incredibly generous and motivated people who put in a lot of hours to make things happen for me… because the week involved a lot of this:

So what was my proposal for? Here’s the one paragraph summary:

Magnetic materials are present in many advanced devices and motors that are indispensible to modern life. Permanent magnets have the ability to enable the conversion between electrical and mechanical energy, the transmission and distribution of electrical power, and provide for the basis of our data storage systems. So-called rare-earth (RE) “supermagnets” are highly desirable because they combine the high magnetization of the transition-metal components with the very large magnetocrystalline anisotropy of the RE components. This magnetocrystalline anisotropy, which donates the high resistance to demagnetization, needs to be replaced in any magnet design that does not include REs. In this work, novel approaches to the synthesis of RE-free nanoscale magnetic materials with significant magnetocrystalline anisotropy and high magnetic energy products will be undertaken. In this manner, results from the laboratory will be more effectively transitioned into technological applications. Two RE-free systems will be created in nanoscale form using rapid solidification processing (melt-spinning, thermal plasma synthesis), thoroughly characterized, and then densified into compacts for mechanical and thermal evaluation. The two materials systems include L10-FeNi and Fe-Fe3O4 in nanocomposite form. Non-equilibrium processing of these two systems is expected to alter the defect density in the L10-FeNi material and alter the oxide cation occupancy trends in the Fe-Fe3O4 nanocomposite; both effects are anticipated to allow tailoring of the materials to achieve high energy products. This research is distinguished in its goal to attain fundamental information concerning high energy product magnetic nanomaterials and to extend these results to pilot-scale production of promising magnetic nanomaterials.

If I get it (a long shot, considering the… you know… one week timeframe of throwing this together), I’d be working with an amazing professor up at Northeastern University, as well as a great partner from the research lab of General Motors. So: hopefully it’ll work out. Without their help, and the help of many many administrators at UT, Northeastern and GM, during this process there is no way I could have got this done. We literally got the last thing uploaded three minutes before deadline! (Pro Tip 5: Don’t do that.)

Anyway, it’s an amazing opportunity, so fingers crossed! In the meantime, this research isn’t going to finish itself…

Austin Marathon: T-11 Weeks Recap

Better week than before… getting back into the swing of things.

Two solid mid week runs:

And a solid 10 miler with Chris on Saturday:

One week until the Decker Challenge (Half Marathon)! Going to continue rebuilding my weekly mileage. 26.2 miles for the last week is good for getting back at it. My goal for this week is 40+. Lace ’em up!