Hunting deep underground for ghost particles

Why study neutrinos?

There's only 12 fundamental particles that the universe is made-up of (that we know of), and neutrinos are three of them. They may be the tiniest, most weakly interacting particles, but we're still understanding the actual building blocks of the universe.

Neutrinos are the hardest particles to measure, which is why they're the most exciting as well, because they’re still the ones that we probably know least about.

How do you go about detecting neutrinos? What sort of places do you work in? 

All of the experiments I work on are deep underground because you've got to get away from the radiation of the Earth's surface. The SNOLAB is 2km underground at the bottom of a Canadian mine. So it's a journey down the shaft and then walking for a mile to get to the lab. Then, when you get there, you have to have a shower before going into the clean room.

The experiment we’re building in Japan, Super-K, is under a mountain; you go horizontally in so it’s a bit easier to access. It's the biggest underground cavity in the world being excavated. It's a huge privilege to work in these places.

What big questions is your research trying to answer? 

I guess it's understanding the nature of everything in the universe effectively! In terms of the neutrinos themselves, we want to understand how massive they are. At the moment, we don't know exactly how much they weigh – we know they're absolutely tiny, but not exactly how tiny.

They also do this strange thing where they change 'flavour' between three different neutrino 'flavours'. We want to characterise the parameters that govern these changes.

There is no antimatter flying around at the moment, but The Big Bang should have made equal amounts of matter and antimatter. Something must have happened in the past to destroy all the antimatter to leave us in this matter-dominated world. We think that the answer to this might be in our neutrino detectors. 

Are there any practical uses which could end up with from neutrino research?

We know that neutrinos are produced in all these distant places in the universe in astronomical events like supernova or black hole mergers. If we understand neutrinos, then we can use them to understand other things, and do astronomy with them. In the same way that infrared astronomy has opened up new frontiers, we could theoretically have the same thing with neutrino astronomy.

So with multi-messenger astronomy we get different signals at different wavelengths from all the different particles of these huge astronomical events, and neutrinos are definitely part of that. 

What is a typical day like for you?

The great thing about being an academic is that there isn’t really a typical day. I work in large international research collaborations, so the first task of the day is always to check my email and follow up on various questions and discussions.

I usually have 1–3 zoom meetings and sometimes some in-person meetings per day – with Japanese colleagues very early in the morning, and with North American colleagues in the late afternoon. There is also teaching and university admin so in term time I spend some of my time lecturing, or supervising students, preparing my teaching materials, or attending university meetings.

I also try to make time to check in with my PhD students and post-doc most days, catching up on their progress and giving advice. In between all those things, I try to do a bit of real research – my favourite is when I am writing code to make plots from the data - either data taken by our experiment in Canada or data collected from small-scale test-setups in our lab at KCL.

You’ve spent most of your academic career working on neutrinos. But going back to the beginning, what did you want to be when you were a teenager?

At GCSEs I was a good ‘all-rounder’, in fact I chose double science to keep my options open, but by the time I was choosing A-levels I knew I enjoyed the scientific subjects most so chose Physics, Chemistry, Maths and Further Maths. I was quite interested in optics and for a while I thought I’d like to be an optician so I arranged some work experience at an opticians and an eye hospital, which I didn’t find as exciting as I hoped!

Honestly, my main ambition was to go to university, I was quite near-term focused and didn’t have a strong idea what career path I wanted to follow.

What attracted you to study physics in particular?

I think I could probably have been happy doing a lot of things, but out of the A levels I chose, physics was the one I enjoyed the most. I realised I like problem solving and logic. I found physics more logical than chemistry and the applications were more interesting that just pure maths. Also, I went to an all-girls school and had enthusiastic physics teachers who encouraged me.

As an undergraduate studying physics, I did a summer internship and at CERN and got assigned to a neutrino experiment there. Those sorts of internships are still offered; it's highly competitive, but it's a brilliant experience if you can get on it.

One final question for you: what advice do you have for young people interested in pursing a career in physics?

There's loads of different things on online, lots of material out there you can read around, and at King’s we run an Online Particle Physics Masterclass. The CERN website has a huge amount of resources too. Dig deeper around the subject, find and follow these opportunities and ignite your interest in physics.

The kind of students who do well at physics are those who want to know why, and don’t just learn things by wrote; those who enjoy the learning, and don’t just want to know what to do to pass exams.

In this YouTube video Jeanne's colleague, Reader in Particle Physics Dr Teppei Katori, , explains his recent art installation 'Particle Shine'. This used live particle detection as the basis for an immerse sonic experience.