By Jake Foster
To many, the Large Hadron Collider at CERN is a place of elusive and difficult science far too complex for most of us to comprehend. Situated 100 metres underground and stretching for 30 kilometres through France and Switzerland, the LHC has been smashing subatomic particles into one another for the best past of a decade, revealing the secrets and inner workings of the universe. For most, the likelihood of seeing inside the world-famous facility isn’t very high, let alone the likelihood of receiving a personal tour from a top CERN scientist. But today, the people of Norwich were given just that, with a little help from the internet.
The Norwich Science Festival treated its audience to a free virtual tour of CERN’s ATLAS Experiment. Our tour guide reporting live via Skype was particle physicist Dr Claire Lee, who works on ATLAS: the largest particle detector experiment in the world. Wearing a hard hat and a head torch, Dr Lee greeted us from inside the facility while standing directly beside the ATLAS detector, images of which are now instantly recognisable across the world.
Our tour began with an overview of the LHC and the work that it does. Dr Lee explained how subatomic particles are accelerated around the 30 kilometre perimeter of the collider, with one beam travelling clockwise and the other travelling anti-clockwise. Both of these beams make over 11,000 trips around the LHC every second. The beams collide inside the detector and release massive amounts of energy, which is absorbed and measured by a device called a calorimeter. These collisions are happening every day and can produce some incredible results, including the creation of the elusive Higgs Boson particle, which is produced one in every ten billion collisions.
With our minds freshly blown, Dr Lee began to guide us (through the power of the iPad’s built-in camera) down one of the facility’s numerous metal walkways surrounding the detector. The walls are adorned with meticulous piping and wiring as far as the eye can see, with much of the metal structure surrounding them painted a bright shade of blue. Considering the facility lies 100 metres beneath the Earth’s surface, it looks remarkably well-lit and spacious. As we were brought to the bottom of a large staircase the live feed camera panned up to reveal the enormous ATLAS detector in all its glory. Weighing in at around 7,000 tonnes, the awe-inspiring behemoth is around 82 feet tall and 150 feet long. Unsurprisingly, it isn’t possible to capture all of it in the frame of the live feed at once.
To make sure we get the best view possible, Dr Lee then guided us back up four stories’ worth of staircases to view the detector from a higher position. From a side view, the detector was shown pulled apart layer by layer to reveal the inner workings of its high-tech mechanisms. Due to the LHC currently being switched off and under maintenance, we were able to view the detector in this unique and informative way. Dr Lee then pointed to a single point within the disassembled detector, revealing it to be the exact point where the particles collide. Witnessing the point at which the highest-energy particle collisions in the world occur is a big deal, and the expressions on the faces of the audience was a testament to this; even the younger members of the audience sat silently, their eyes glued to the screen.
Further explanation of the facility’s construction and difficulties was fascinating. We learned that the entire detector is tilted by one degree in order to compensate for the angle of the particle beam. All 30 kilometres of the LHC has to remain perfectly aligned in order to work properly, and the engineering involved is breathtaking to behold.
After around 40 minutes we reached the Q&A part of our virtual tour. The clearly engaged audience asked some big questions, which Dr Lee answered with enthusiasm, verve and a wealth of expert knowledge. When asked what was actually being discovered at CERN, Dr Lee explained how the Standard Model of physics is used to define the fundamental forces and elementary particles of the universe, and while it is incredibly accurate there are still some questions that remain unanswered. This includes the mysterious way in which neutrinos behave, which current theories still cannot understand. She describes the ATLAS experiment as a “giant Standard Model test machine”. The research conducted at CERN can solve these questions and so many more in order to help us understand how the universe works.
Dr Lee’s explanations broke down complex scientific theory into digestible chunks filled with awe and wonder, making her the perfect tour guide for our virtual visit. This event was a joy to see, and it is sure to have inspired a few future scientists in the audience. For a very enjoyable hour the people of Norwich were let inside the world’s largest science experiment, all without needing to leave the Forum.