Science Research at UvA-VU: Nikhef
What happened after the Big Bang? Where did all the antimatter go? What is dark matter made of? These are some of the fundamental questions of subatomic physics. Gerhard Raven, Professor of Experimental High Energy Physics, is trying to arrive at some answers, along with his colleagues from Nikhef.
Nikhef is the National Institute for Subatomic Physics, a partnership between FOM, VU Amsterdam, University of Amsterdam, Utrecht University and Radboud University Nijmegen. The institute carries out research into particle physics and astroparticle physics. Gerhard Raven’s work focuses on the former. He runs the research programme for the LHCb experiment together with Marcel Merk (who holds a special chair at VU Amsterdam) and Antonio Pellegrino (who holds a similar position at Groningen University).
Matter and antimatter
‘At the time of the Big Bang, an enormous amount of energy was released, creating equally enormous amounts of matter and antimatter,’ explains Raven. ‘When these particles came together again, they were annihilated, producing energy and light. But how come our current universe is devoid of antimatter, and filled with matter? Probably only a tiny fraction of the particles of matter created are still there; it is this difference that allowed the universe as we know it to come into existence.’
Raven and his colleagues examine this question making use of the Large Hadron Collider (LHC) at CERN in Geneva. In this particle accelerator particles collide at tremendous speed. By looking at the process of decay and the traces of elementary particles called ‘beauty quarks’ and ‘anti-beauty quarks’, they are able to study the tiny differences between matter and antimatter.
The Standard Model, which was developed in the 1960s and 1970s, is the central pillar of particle physics. The Standard Model was proven to be mathematically consistent and correct with the discovery of the Higgs boson in 2012. But even so, it is not possible that the theory is complete. ‘The difference between matter and antimatter is much larger than the Standard Model predicts,’ Raven continues. ‘But all the measurements we have done so far have been consistent with the predictions. All the tests add up. So we must be missing something. We just don’t know what yet. The theory is not consistent with the universe.’
Colleagues from the University of Amsterdam, who are working on the ATLAS experiment at Nikhef, are also looking at the Standard Model. ‘Because we are approaching the same problem from different angles, there are many opportunities for cooperation while still retaining our own distinctive profiles. Our research is not the same, but there is a lot we can do together. For example, our colleagues from the University of Amsterdam have expertise that we can use too. If we run into a problem, we can just drop by for a visit.’
Trying to solve the mysteries of the Standard Model is not the only thing that researchers from VU Amsterdam and the University of Amsterdam have in common. They are also developing new software together to process the data from the measurements, and they use the same supercomputers at Amsterdam Science Park. They regularly discuss the results of the experiments during the weekly Friday afternoon drinks.