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Alaska earthquake shakes up Tevatron
The Tevatron, the world’s highest-energy particle accelerator, is so sensitive to its environment that it felt the effects of the Nov.3 earthquake in Alaska — some 6,000 miles away. The earthquake, whose maximum magnitude registered at 7.9 in the vicinity of Denali National Park, caused the Tevatron to vibrate and lose its particle beam at around 4:30 p.m. (Central time) that Sunday afternoon. But it took an alert troubleshooter, checking the machine logs from his home computer while watching CNN on TV Sunday night, to finger the earthquake as the cause. Duane Plant, of Beams Division/Engineering and Support, noticed beam loss over a long interval before the machine quenched, or warmed above superconducting temperatures. “It was similar to a loss we saw back in June, when there was a smaller earthquake down in Indiana,” Plant said.“That earthquake didn’t quench the machine but it made a small loss pattern. This looked similar to me, so I went to some web sites of the U.S. Geological Survey, got the earthquake times in Alaska, and did a ‘back-of-the-envelope’ guess on the time it would take to get here. That guess was within two minutes of when the logbook showed the quench.” Plant got on the phone with Beams Division Tevatron specialist Todd Johnson. The two spent about an hour on plots and figures, and decided it was time to call the crew chief in the Main Control Room with the earthquake scenario. “Since the crews couldn’t find any other cause for the quench,” Plant explained,“we thought maybe it was best to just go ahead with the next step in reestablishing the beam, instead of spending another four or five hours looking for the cause. We thought we understood the cause — as absurd as it sounded.” On Monday morning Plant, Johnson and MCR Operators checked with the seismology center at Northern Illinois University in DeKalb, and confirmed that the wave arrival times from the earthquake coincided with the effects felt at the Tevatron. Instrumentation in the Beams Division had recorded position shifts of 30 microns in the Tevatron and other accelerator components — about three times the width of a human hair. And just down the road, Argonne National Laboratory reported beam loss in its Advanced Photon Source at virtually the same time as the Tevatron. “So much can affect the beam here at the lab, you have to keep your eyes open ‘way outside the box,all the time,” Plant said.“Then again, with a machine like this, operating out at the edge, there is no box.”
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