The new CERN visitors' center.
Back in July, we were fortunate enough to have the opportunity to tour CERN, home of the Large Hadron Collider. In addition to getting some great information on how the machine gets protons up to speeds nearly that of light, and finding out the sorts of physics that scientists hope to find in its collisions, we also got a great view of some of the control rooms and hardware that help keep everything humming along. Unfortunately, with the LHC active, it wasn't possible to actually go down and see the massive detectors that capture the output of the proton collisions, but there's still a lot to see around CERN.
To handle the interest generated by the LHC, CERN has built a new visitor's center to introduce the public to the work that goes on there. For this visit, however, the tour started across the street, next to the CERN gift shop (yes, it has a gift shop).
The new CERN visitors' center.
CERN has been in the business of smashing atoms for several decades now, and reminders of its past show up in many areas of the center. I'm not sure what this is, but its shape evoked that of the new CERN visitors' center, which rises behind it.
Some exotic-looking silver hardware rises in front of the CERN visitor's center (brown dome in backdrop).
Other hardware doesn't quite get this honorable treatment. This bit of hardware was resting outside the facility in which the LHC's magnets are stored and tested. Again, its function isn't clear, but it was obviously the wrong size to link up with any of the pieces being used in the LHC.
It's not clear what this is, but it doesn't seem likely that it will see further use.
Inside, however, the hardware was cutting edge. The accident that occurred during the LHC's start-up depleted the supply of replacement dipole magnets, and CERN is refreshing its stocks. Each magnet is tested extensively under operating conditions, which means lowering them to near absolute zero using liquid helium.
Magnets (blue tubes) at rest in the testing facility.
Lots of customized hardware appears to be needed to control the conditions that the magnets will face during operations, and to read out the performance of the hardware being tested.
Lots of electronics control the testing procedure. The end of a magnet is visible to the left of the image.
The magnets themselves are the product of one of the many international collaborations that built the LHC. As the labels here indicate, these magnets were produced by a combination of the KEK physics labs in Japan, and the US' Fermilab. The orange tubes are quadrupole magnets, which help shape the beam as it circulates through the LHC.
Quadrupole magnets sit in reserve in case they're needed to replace failed hardware in the LHC.
Blue tubes hold dipole magnets, built by a collaboration led by Brookhaven National Lab. They help steer the protons around the machine's circumference. But far more than protons need to go through each segment-power, refrigeration, and control electronics all need to be in place, and they need to be built to survive at temperatures near absolute zero.
A dipole magnet's end, revealing that the proton pathways (the paired tubes flanking the center) are only a small part of the necessary hardware.
It isn't just that the hardware has to be tough; it also has to be flexible. As it's cooled, each segment contracts by about four centimeters, so everything inside has to have joints that can flex accordingly. The power supply travels across the structure in the center, where the basket of individual wires allows the hardware to expand and contract.
A cutaway showing some of the hardware inside a dipole magnet.
The LHC's hardware isn't the only thing that has backups; most of the facilities we saw were in close proximity to warehouses that also stored equipment ready to be used if needed. So, it wasn't uncommon to emerge from an ultramodern control room and behold a set of dusty hardware of mysterious purpose.
Presumably, someone at CERN knows what these are for, and where to find them.
Old accelerator hardware isn't the only thing kept around. At the CERN computing center, a rather significant NeXT cube is kept behind a glass cabinet: the world's first Web server, complete with a note asking people not to shut it down.
Some hardware left behind by Tim Berners-Lee.
one of the surprises of the grid computing effort has been how well the networking setup has performed. So, it was no surprise to find huge amounts of rack space dedicated to linking everything up.
A heavy investment in networking hardware has helped keep the LHC's grid humming along.
Another pleasant surprise has been the price and performance of disks. The original plan was to have data stored primarily on tape, but cheap disks and distributed storage have worked so well (and done such a good job of feeding the network) that disks have seen increasing use at the CERN computing center.
Large racks of disks sit between the tape archive and the grid and help handle fast access to data.
Still, the majority of storage present comes in the form of tape archiving, albeit on a grand scale. This robotic tape housing can rapidly pick out the tape that holds specific pieces of data, and bring it to one of a small collection of read/write hardware housed in the same structure.
Robotic arms help get data onto and off of tapes at a reasonable pace.
Although we weren't able to get down to the detectors themselves, we were able to see the control rooms that sit above them. Here, the exterior of the ATLAS control building displays a mural of the detector itself, complete with a collision taking place.
The exterior of the ATLAS detector control building..
We weren't allowed inside the ATLAS control center, but were able to take pictures from just outside. It looked like a variation on most of the others we saw, though: lots of large displays, helping researchers keep track of what's going on in the hardware through detailed depictions of it.
Looking in at the ATLAS control room from beyond its glass walls.
The people who run CMS, a second detector, are a bit more relaxed about visitors, at least while the machine isn't gathering data. We were able to wander through and take photos as the researchers went about their business, and sat down for an interview with a physicist right at one of the desks there.
Inside the CMS control room.
The day ended with a trip to the control room for the accelerator itself. This required a trip over the French border; the tour guide drove us through an unoccupied border post, before pulling up at an unassuming building...
No, this building does not house the actual control room, which is off to the left.
The building that houses the control room, although a bit more modern, isn't any more auspicious looking from the exterior.
The building that houses the LHC control room is a relatively recent addition to the CERN campus.
Inside, the control room looked similar to the ones that control the detectors: plenty of large monitors that help the people running it keep track of what's happening dozens of meters underground.
Even in a down period, there's plenty of activity in the LHC control room..
Outside of the magnet testing facility, this was the only place where custom hardware was apparent. For the most part, everything that happens at the LHC is directed through commodity hardware.
A bit of custom hardware appears at the right of this photo; most of the visible hardware is all standard PC equipment.
The control room, where the accelerator's director helped explain how all the hardware fits together, was our last stop of the day.
