Research Fellows Directory
Dr Sarah Malik
Imperial College London
It's remarkable that more than 80% of matter in the Universe is invisible to us, it does not emit or reflect radiation; its what we call "dark matter". We know it exists because it exerts a gravitational force on ordinary matter, playing a critical role in holding together galaxies and shaping the Universe as a whole. There's reason to believe that it comprises of particles that have mass, are electrically neutral and don't decay; beyond that, we have little understanding of dark matter. How many types of dark matter particles are there? What types of forces do they exert on each other and on the ordinary matter particles?
My research will aim to address these very questions.
Using the Large Hadron Collider (LHC), my project aims to produce dark matter particles and then detect them. At the LHC, bunches of protons are accelerated to very close to the speed of light and then made to collide in one of the large detectors which act as giant digital cameras, capable of taking 40 million snapshots a second of the collisions.
In these collisions, the energy of the protons is converted into the mass of new particles, which could be potential candidates for dark matter. Since dark matter carries no electric charge, these particles would leave no trace in our detectors and their presence must be inferred by applying momentum conservation and attributing to them any imbalance in momentum. Its the same principle that was applied by Wolfgang Pauli back in 1930 when he correctly predicted the existence of the neutrino. He observed that energy was not being conserved in radioactive decay and hypothesized that this was due to an electrically neutral particle carrying away some of the energy. In much the same way, I'll look for collisions where there is an apparent imbalance of energy to detect dark matter particles.
With the LHC currently colliding protons at unprecedented energies, the next few years promise to be exciting in shedding light on dark matter. Discovering what 80% of matter in the Universe is made of will play a significant role in defining the future direction of particle physics and cosmology and mark an extraordinary development in our understanding of the world around us.
Interests and expertise (Subject groups)