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CERN | Geneva | Switzerland

View Blog | Read Bio

First collisions of the year, all hopes are allowed

This morning at 00:37, the Large Hadron Collider (LHC) at CERN brought two stable beams of 4 TeV protons into collision for the first time both for this year after the winter shutdown and for that energy. This comes after weeks of preparation by the LHC’s team of operators, technicians and accelerator physicists. The experimenters have also been working hard to complete all necessary work on their detectors in time and test new software. Everybody had been waiting for this important event with great anticipation.

Preparing to take my first shift of the year in the ATLAS control room this week reminded me of first day of school when I was a kid. My clothes were laid down on my chair, my breakfast ready and I had enough food packed to sustain a small siege. I certainly did not want to be late for the start of my shift yesterday at 7:00 am when the first collisions in stable beam conditions were expected.

The ambiance around the ATLAS control room was particular this week with everything and everybody just waiting for this event. So every time a new glitch appeared, experts rushed in, trying to get all wrinkles ironed out before the LHC finally announced they had completed all their checks and measurements, and the next fill would be for real physics.

The whole morning shift crew, about ten people including myself, had been hoping we would be there for this important milestone. As we walked in at 7:00 am, the LHC was delayed by a small glitch that got fixed rapidly. Then they needed to complete one last measurement but lost the beams before completing it. For hours, we kept hoping for some interesting action.

There was not much to do but wait and see if and when the LHC team would be ready. The shift was punctuated by the usual succession of dead quiet periods followed by frantic bouts when one system went bad, a new alarm went off or the daily run meeting ended.

These meetings are held seven days a week just above the ATLAS control room and bring together all system coordinators and experts on call, the run manager (the person on call to assist the shift leader for a week at a time, 24 hours a day) and run coordinators. More than forty people review all recent problems, establish the plans for the day according to the latest news from the LHC, repairs necessitating an access to the detector cavern or special tests being conducted. So every day after the meeting, all the experts drop by to leave instructions with the shift crew, make a few tests or fixes, bringing the control room into a buzzing state. There is a whole sub-culture within the collaboration of people who constantly orbit around the control room, making sure all is always in the best possible running condition. The others only come occasionally to take their share of shifts to staff the control room at all times.

Part of the shift crew in ATLAS control room in the early afternoon while waiting for the first stable beams.

(Photo: Claudia Marcelloni de Oliveira)

As shift leader, my role became really secondary, with all the key players in place. Most of them are students or young postdocs, more than half being women, reflecting well the crucial role taken by young people in the collaboration.

Some already looked tired, having been called a few too many times in the middle of the night already to fix problems while we still had time.

Bringing large detectors like ATLAS out of hibernation is a delicate task and new problems are bound to keep showing up. The whole detector is made of 7000 tons of delicate and complex equipment, 4000 km of cables of all sorts and as many kilometers of tubing, all bringing voltages or special fluids to the detector or taking information out. This in part explains why nearly 4000 people are now involved in each of the ATLAS and CMS collaborations, the two largest LHC experiments. ALICE has about a thousand researchers while LHCb around 1500.

The other reason is the attraction of the possibilities to make great discoveries.. What could it be? No one knows yet but it sure looks promising not only for getting the final answer on the Higgs boson but also on testing many new theories.

Pauline Gagnon

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