During the ‘long shutdown‘ CERN opened many of its site to be visited upon by thousands of visitors over a two day weekend on 14 and 15 of September 2019. I was one of those visitors, after having found out about the whole event in June on the morning that registrations opened.
I managed to register at sites, but the way it functioned was that this was more like a registration as to when you arrive. Therefore, if you did not register for the sites that you wanted to visit you can still do so. There were ample opportunities to get registered. The biggest challenge was getting yourself to Geneva in the first place and making it to the sites. I managed to do a tour of two sites – the LHCb experiment (day 1) and ALICE (day 2).
Day 1: LHCb – Large Hadron Collider beauty experiment
The LHCb experiment is one of seven particle physics detector experiments collecting data at the Large Hadron Collider accelerator at CERN. LHCb is a specialized b-physics experiment, that is measuring the parameters of CP violation in the interactions of b-hadrons. The 5600-tonne LHCb detector is made up of a forward spectrometer and planar detectors. It is 21 metres long, 10 metres high and 13 metres wide, and sits 100 metres below ground near the village of Ferney-Voltaire, France. About 700 scientists from 66 different institutes and universities make up the LHCb collaboration (October 2013).
The tour group that we had was headed by a PhD student candidate in physics, who’s name was Bartosz although I didn’t catch the rest of this full name to give him credit!
The first stop (photo above) was the control room where he talked about a typical day of the scientists and operators involved in the 24/7 upkeep of the accelerator.
Next, we moved on to a few exhibition type of rooms holding a miniscale model of the accelerator, a map overlooking the entire area over some French villages on the Swiss borders.
And then it was time to go underground – about 102 to 103 metres underground! Below are photos of the LHCb experiment:
LHCb data centre
Following the tour underground, we headed overground to look at the data centre processing the results. These data centres are housed in separate containers outside the site and kept cool via the additional containers above it. It is expected that considerable amounts of data will be collected in the next iteration of LHCb and they are also preparing the data centres for it.
Following by two very notable and very interesting sites:
Quality control and assembly (for hardware, parts) site showing Scintillating Fibre Trackers
Unfortunately, I forgot the official name of this site, but they have a separate warehouse which is entirely dedicated to assembling the necessary components for the LHCb accelerator. In this case and during the Open Day, they have the Scintillating Fibre Tracker and paper here.
One of the amazing things to learn about this is that absolute precision that is required, as it requires to be absolutely straight. It cannot be even a few degrees tilt as it would affect accuracy of the results. Even the frame itself has mechanism to avoid condensation, as condensation itself would affect the ’tilt’.
The CERN Axion Solar Telescope (CAST)
The CERN Axion Solar Telescope (CAST) is an experiment to search for hypothetical particles called “axions”. This experiment has been ongoing for at least two decades and is set to continue on.
The telescope will actually only power for a brief moment, about 10 minutes, each sunrise and sunset collecting data. It requires immense power to refrigerate to -270C (temperature for outer space) and pictured below is one of the mechanisms to keep it cool:
And that is it for the first day! Coming soon will be all about the second day.