Wednesday, April 30, 2008

Shaken But Not Stirred

Although it isn't designed to detect earthquakes, many synchrotron facilities around the world, especially the latest generation facilities, can actually detect when an earthquake is occuring, some time halfway around the world. The recent earthquake in Southern Illinois that occured a couple of weeks ago was certainly felt in various parts of Chicago, and it was certainly detected by the Advanced Photon Source at Argonne.

The magnitude 5.2 earthquake that shook southern Illinois was “detected” by the beam position monitors that keep the electron beam on course in the APS particle accelerator (see the accompanying figure), but the machine continued to orbit electrons at nearly the speed of light with no noticeable adverse effects. Other monitors (x-ray beam position monitors) assured that x-ray beams illuminated experiment samples as small as molecules.

There are of course many steps in place to either make sure the beam continues to be stable, or in the worst scenario, that it gets dumped safely if it goes too far off course. The same thing is in place in many other facilities around the world, especially the LCLS being constructed at SLAC in the earthquake-prone California, which has an even more stringent beam operating parameters to produce its FEL.

I was told by someone working at the APS that they even detected the huge earthquake in the Indian Ocean from a few years ago that caused the massive and deadly tsunami. So this is one very sensitive machine with very precise diagnostics ability.


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