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Tevatron Saw the Haiti Earthquake January 19, 2010

Posted by gordonwatts in D0, Fermilab, physics, physics life.

The Haiti earthquake registered was a 7.0, and devistating, as everyone knows. Illinois and the Tevatron are about 2500 miles away from Haiti – but the Tevatron did see the earthquake:

haiti_quake2[1]What you are looking at there is an ACNET plot. I stare at plots similar to this when I’m on shift all the time. The top two plots – the green and red, are position monitors on the quadruple magnets just outside CDF and D0. They are quite stable until the earthquake. The Tevatron was running when this happened, and you can see in that lower red plot that some protons were knocked out of the ring by the ground shaking.

Note these movements are so small you never would have been able to detect them unaided. However, as my wife put it, “that is one expensive seismograph!” :-)


1. Gordon Stangler - January 20, 2010

How comes it takes the beamline so much longer to settle down compared to the pitch and roll graphs? I would have imagined that the beams would clear up the shaken particles fairly quickly, and rapidly flushed them out of the Tevatron.

2. Charlie - January 21, 2010

I’m no Tevatron expert, but in our experiments, we often find that different sensors (tilt, seismic, and the experiments themselves) have rather different responses to individual quakes. I’ve not delved into any of our data during the Haiti quake, but the Earth tends to ring for significantly longer than 15 minutes after a powerful quake. The tilt in Chicago might have settled down fairly quickly while some transverse rumble persisted longer.

Also, the beam response might be more nonlinear/sensitive than the tilt sensors. The tilt data after 16:30 still show significantly more noise than the pre-quake traces, so the Earth is still rumbling.

The timing of some of the transients is interesting – the initial DC transient arrives earliest in the beam data, but in general, the beam looks to have some low-passing in its response to the disturbance. That might be due, again, to the differing kinds of sensitivity, purely instrumental in origin, or both. The S, P, and Love waves all travel at different speeds – enterprising folk can compute the quake’s distance from the detectors. The USGS has a nice p-wave travel time tool to get them started/help cross-check results. Looks like the tilt data will give the best timing.

It could also be some unhappy resonances in the beam feedback system, but I doubt it – Tevatron folks are good at what they do, and resonances like that would probably be a perpetual problem. At least two brains await Gordon’s reply!

3. Gordon Watts - January 21, 2010

Gordon – I think Charlie is right, the earth is still ringing after the initial large shockwave. Loosing particles is almost certianly a non-linear process as you guessed Charlie – though I’m not aware of any accelerator-earthquake studies!

Sorry I didn’t see the reply ealier, Gordon, somehow it got lost in my email.

4. Christoph Paus - February 2, 2010

Hi Gordon;

this is interesting. We had a similar event with the L3 detector at the time. There was a rather strong Earthquake in Turkey at the time and the L3 detector was mounted on a support tube what was pretty long.. don’t ask me the exact length but it was more then 10 m. A friend of mine used the data of the automatic hydraulic jacks to triangulate the quake and found the right direction… pretty amazing.

Cheers, Christoph

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