Dr Saskia Charity
Saskia is a tenure track research fellow in physics in the Faculty of Science and Engineering.
What is your research about and what types of scientific techniques do you make use of?
I work in experimental High Energy Particle Physics, specifically in the field of precision muon physics. I work on two experiments – the Muon g-2 Experiment at Fermilab, USA, and the MUonE Experiment at CERN. Both experiments make ultra-precise measurements of subatomic particles called muons, which are like electrons, but 200 times heavier.
Muons are useful particles for studying the “Standard Model” of particle physics, which is the theoretical framework that describes all known particles in the universe and how they interact. It is an extremely experimentally successful framework, but it says nothing about gravity, and it cannot tell us about Dark Matter or Dark Energy, the mysterious substances that make up 95% of the mass of the universe.
The field of Particle Physics is concerned with trying to explain why we’re unable to account for this missing mass – is something missing from the theory, or are there new particles or interactions that we haven’t measured yet? The precision muon experiments that I work on can shed light on this puzzle by looking for tiny discrepancies between the Standard Model predictions and experimental measurements.
If our results show deviations from the theory then we could find concrete evidence for particles or forces from beyond the Standard Model, and shed light on one of the major problems in modern Physics.
What or who first inspired you to be interested in your research subject?
I think the point at which I knew I was going to be a particle physicist is when I learned at school that everything around us, including solid objects, is almost entirely made of empty space. I wanted to know what was going on in that space!
I chose to study Physics at university because I was interested in explaining why scientific processes happen at a fundamental level. I kept asking “why” until the answer was “nobody knows”!
What are you most proud of achieving during your research career so far?
Working in Particle Physics means being part of large international collaborations of scientists – in the case of muon g-2, there are about 200 people. Having been part of this collaboration for over a decade, I’m proud of the research environment we created and how well we worked as a team to provide a world-leading measurement.
Working on large experiments means that there are often difficult challenges that require innovative ideas. This means that everyone, from early career students to experienced senior scientists, needs to have their voice heard and feel comfortable to express their ideas and have their work supported. I think our collaboration worked hard to ensure this was the case, and it enabled us to achieve our goals.
Which other subjects are important for your research?
In experimental particle physics, we always need to learn new skills and be able to use the latest technology to design our experiments. Advancements in electronics are very important to us as they enable us to build detectors capable of processing data at very high rates.
Likewise, the volume of data we need to process and the precision we are working to mean we need to understand (and sometimes create ourselves) the latest computing tools to process our data efficiently and accurately.
We also work very closely with our theoretical physics colleagues in the Maths department who are thinking about how to explain any puzzling experimental results we measure.
What is the key to running a successful research project?
Collaboration and teamwork are essential. It’s especially true in particle physics, and probably also in other fields, that no research project happens without a team. When building a particle physics experiment, you need to collaborate with a whole team of people from different areas of expertise to make the project a success.
When managing my own project as a contribution to these experiments, I need to consider how my work fits into the needs of the team. It’s important to get to know everyone well so that I know who has which areas of expertise, and who might be able to advise me if a certain idea is worth pursuing or if it needs to be developed.
How do you plan to develop your research in the future?
The future of the experiments I am working on depends, to some extent, on what we measure. If our experiments measure evidence of physics beyond the Standard Model, then we will need to design experiments to test what we’ve measured and understand what could be causing the discrepancies.
The MUonE experiment is proposed to start taking data after the CERN long shutdown in 2029, and we would run for three years to collect the statistics needed to compare to the Fermilab muon g-2 experiment result. At the same time, theoretical advances are also helping to pin down the Standard Model prediction.
Within the next few years we should know whether or not the muon exhibits signs of Physics beyond the Standard Model. If the discrepancy goes away, then many theorised models for new particles and forces will be ruled out, so we will need to think about how to design experiments or detectors to search for new physics in a different way. If we do confirm a discrepancy with the Standard Model, this would be a major scientific milestone, and would allow us to think creatively about new ways to study the possible interactions that cause the difference.
What advice would you give to someone considering a career in research?
It’s important to find something that really motivates you, as research can be frustrating in many ways and it can be difficult to see the big picture when you are focussing on a specific problem.
I find that I enjoy learning new skills to help me solve problems in different ways, and that keeps me motivated even when it feels that our results are in the distant future. Also, it’s important to build a team of colleagues who you enjoy working with!