A large part of the last several weeks has been spent ordering equipment (and making sure it’s the right thing before ordering!). I have become very familiar with our purchase request form, as well as our support staff responsible for placing the orders. I am not above bribing her with espresso so that not all of our interaction is based around me making more work for her.

This period of time involves lots of planning, both short and long term.

For instance, I’m going to build an x-ray hutch. And this isn’t your father’s Oldsmobile style table top x-ray enclosure/hutch. No, no... this is a full sized, walk-in, large hutch capable of housing a large diffractometer. So, how big do you make the hutch? Well, funds are finite, so “as big as I want” isn’t an answer. But, making it big enough to eventually house 2 different sources and hutches is reasonable. Especially as building a large single hutch is much less than building a second hutch later on.

But it’s not just finances and logistics either. There are two different basic philosophies here. One, push everything as close together as possible and use no focusing. You’ll use a flat mono-chromator, minimize the total flight path, make alignment simpler, and have less attenuation from air-scattering of the x-rays. There are down sides too though. Frequently in this scheme your sample will only select a portion of the x-ray beam instead of the entire thing. The other philosophy is to move things out a bit, use a curved mono-chromator, and have the beam focused to a small size at the sample. This can increase the number of x-rays (assuming you’ve taken care of that nasty air-scattering) on the sample, lower backgrounds, and allow for more powerful selection of smaller regions of your sample. The price here is increased complication in set up and, often, requires more frequent “fine tuning.” So, that simple decision can mean a couple of extra meters of distance (or the other complication of having the source outside the hutch). Nothing is simple!

In my case I’ve opted to “supersize” the hutch, but to go with the shorter instrument geometry.

That also effects other things. Do I need 1 optical table or 2? Can I get a spare vacuum pump easily? Do I design the flight path to be evacuated (or filled with helium)? So many things to decide... and it needs to be in my head before placing the orders!

The 2nd worst thing to a completely empty lab, is a half filled lab where the budget has absolutely run out. So in the back of my head is always the idea that I need to make sure we get this instrument completely working before I spend too much money on other equipment and projects.

One very fun aspect of this is that I get to do much of the reading and work for this at home at night. As such Linus gets to help.