Kamchatka quake reaches Diamond

Diamond’s ultra-precise beam is constantly monitored by diagnostics called beam position monitors. Almost 200 of these devices are distributed around the 561m circumference of the ring, ensuring the circulating electron beam and consequently the emitted X-ray beams stay stable when the machine is in use.  Due to the sensitivity of these diagnostics, observations of the tiniest of ground vibrations are possible. During the Kamchatka quake, disturbances were detected in the beam’s stability, a result of the seismic waves travelling over 8,000 kilometres from the epicentre.  

The diagnostics, designed to measure beam position and performance with extreme precision, picked up these disturbances in real time once they propagated to reach the UK. The electron beam circulates in a closed orbit at nearly the speed of light and because it is so finely tuned, even minute ground vibrations cause detectable shifts in its path. 

Figure 1: Electron beam position monitor at Diamond Light Source

“We saw the effects of the earthquake last week and were able to see how much of the disturbance we mitigated with our orbit feedback” explained Lorraine Bobb, Head of the Diagnostics Group at Diamond. 

Michael Abbott, the senior software engineer in Diagnostics, added: “The electron beam position moved by about half a micron (with orbit feedback enabled), when observed for 1.6 seconds per measurement, and the disturbance lasted for two hours.” 

The Kamchatka earthquake, which triggered tsunami warnings across the Pacific, was one of the most powerful seismic events since records began.

The earthquake happened very early in the morning during a scheduled machine development day, meaning no user experiments were disrupted. “Thankfully, we didn’t have any users at the time,” Lorraine said. “But it is remarkable how easily we detect disturbances like this from the other side of the world.”

The beam’s response to the Kamchatka quake was not only visible but also measurable. The orbit feedback system - designed to stabilise the beam against environmental noise - was able to dampen the beam motion caused by the seismic disturbance by a factor of 10. “This is what we can achieve with our current system,” Lorraine noted. “The system we’re planning for Diamond-II should be far superior.”

Figure 2: Measured beam motion with and without fast orbit feedback

The major machine upgrade, Diamond-II, will deliver a new storage ring with enhanced beam stability and brightness. The new system will be better equipped to handle ground motion, power supply ripple, and other sources of beam instability. 

So, beyond its primary use for synchrotron science, Diamond is also proving to be a tool for geophysics. Lorraine said: “The electron beam of Diamond also effectively serves as a giant seismometer. It may be possible to even look at the coherence and wavelength of the ground disturbance, given the size of our machine. It’s not the first time we’ve detected earthquakes, but this one is extremely clear to see.”