analyzer modsWe’ve been in the process of getting ready for next week’s upgrade to my experiment. Currently we take ten measurements simultaneously–we’re going to bump that up to 19.

Here’s a quick refresher for those of you who forgot what I do: basically my instrument is a big detector for measuring inelastic x-ray scattering, i.e. we’re looking at the energy loss spectrum of the x-rays. Likewise, the change in trajectory (or scattering angle) indicates the x-ray’s change in momentum. So, since both quantities are conserved, where does the energy and momentum go? In our case, it goes into kicking out an electron from some atom to some excited state. We tend to stick with units of energy and momentum in our analysis, but you might realize that the reciprocal quantities are time and space–so one aesthetic interpretation of our data is that we’re literally recording movies of the electrons getting sloshed around by our probe (as opposed to a snapshot of the electrons). This is the fluctuation-dissipation theorem in a nutshell. Hmmm…that was less than brief.

Anyways the tools for measuring these things are analyzers and detectors. The analyzers collect a large solid angle of photons and focuses a small number with a certain energy back to our detectors. This system isn’t perfect and lots of stray photons (noise) could find the detectors. For instance there are approximately 10000000000000 photons impacting our sample every second and we are only interested in maybe 0.000000001% of them. That means we need lots of baffling–the detector box shown below incorporates a lot of spatial filtering. It’s a pretty effective system, but the ray tracing has to be just right, so I’ve been worrying about mils lately.

detector mod

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