Clara Nellist

Thank you for choosing me as the winner! I had an amazing time answering all the fantastic questions!!

Favourite Thing: Experiment! And really, that’s what science is all about. Saying, “I wonder what happens if I do this…”



Barrs Hill School & Community College 1998-2005; University of Manchester 2005-2009 & 2009-2013


A-Levels: English, Maths, Physics, Chemistry; MPhys (Hons): Physics; PhD: Particle Physics

Work History:

Fermilab 2008-2009; CERN 2009-now (as well as shop assistant, barmaid, receptionist…)

Current Job:

Post-Doc at the Laboratoire de l’Accélérateur Linéaire (Linear Accelerator Lab)


Centre National de la Recherche Scientifique (National Center for Scientific Research)

Me and my work

I design and test pixel detectors (like those in your digital camera) for the ATLAS detector at CERN and I also study what happens when a Higgs boson turns into taus (heavier versions of electrons).

I work on the ATLAS experiment at the Large Hadron Collider (LHC) at CERN in Switzerland. But I live in Paris and just head over to Switzerland (and sometimes Germany) to do experiments or to meet with people.

At the LHC we send protons (one of the particles in the nucleus of atoms) around a huge ring which is 27 km long and 100 m underground. These protons travel very close to the speed of light and when we think they’re going fast enough we smash them together! This collision happens in the centre of the ATLAS detector (and at other detectors around the ring) to make new particles. One of the new particles we make is the Higgs boson which was only just discovered at CERN in 2012 (it’s also known as the God particle, but I don’t use that name).

Some of these particles have never been studied before, and from them we can learn what the universe is made of and how everything works.

You can think of the ATLAS detector like an onion (like Shrek), it’s made up of layers, and also like a camera, it records information about particles that pass through it (although a camera only does light, this does almost everything). Each layer does a different job, but the layer I’m most interested in is the first one, the pixel detector.

The pixel detector tells us where particles with charge (such as an electron) have gone (which is called tracking). But because it’s first, it gets badly damaged by all the radiation from the particle smashing. So I design and test newer pixel detectors to make them faster, last longer and give us more information (like when you upgrade your camera from 10M to 16M).

The other half of my time I spend studying the Higgs boson, and specifically what happens when it turns into two particles called taus. Taus are just heavier versions of electrons, but because they’re heavier they can change into a lot of other particles. There are theoretical physicists who tell us how often the Higgs should change into different particles and we want to see if they’re right. Although, it’s always more fun when they’re not! It means theres more to find out and that’s what science is all about! 🙂

And if you made it this far, thank you! Also, check out the photos at the bottom which should help to explain everything I’ve just said.

My Typical Day

I can usually be found doing experiments in my lab or at my computer running a simulation or analysing data (if I’m not in another country, that is!).

I don’t really have a typical day, which is brilliant because I like to keep things interesting.

If I’m in Paris, I could be in my lab either putting together equipment, or running an experiment. Generally, I will take a new pixel detector and put a lump of something radioactive on top of it. Radioactive means that the atoms will release a particle because they’re not stable and I can use this particle to test if my detector is working properly. When I’m finished testing it with a source of radiation, then I get the lasers out :). Once I know my new detectors well enough, I’ll take them to an experiment at CERN to use a bigger beam of particles for testing them.

If I’m not in the lab, I’ll be in my office looking at some data from the ATLAS experiment, or maybe running a simulation (getting the computer to show me what we think is happening). Or I’ll be working with the other scientists and PhD students, talking about ideas for experiments or last night’s television.

I could also be in a meeting. Because the experiment I work on is massive, and it needs so many people (about 3500 people), often they’re not all in the same place. In fact they’re all over the planet! So to have a meeting, we have it virtually, online like a Google hangout or a Skype chat.

Although, sometimes we do need to be in the same place. For example when we need to have a meeting with a lot of people (and it would just be confusing to have that many people online) or when we want to present our work to other scientists at a conference. In this case we have to travel for it, and this has given me the opportunity to visit some amazing places all over the world. My favourite was a conference in Disneyland in California! I got to go on roller coasters in my lunch break!!

What I'd do with the money

Too many possibilities! But I think I’ve narrowed it down to supporting the International Masterclass programme.

There are so many wonderful projects that could benefit from this money that it is really difficult to only choose one!
Something I would like to support is the international Masterclass programme ( by expanding it to schools in remote locations (such as countries where they don’t already have any Masterclass events). This programme brings scientists into the classroom to enable students to perform measurements on real physics data. They then connect to other schools around the world to discuss their results, just like real scientists.

I would use the money to travel to the school with a Masterclass kit and give talks to the students about CERN and being a scientist. This could be combined with a Virtual Visit to the ATLAS Experiment at CERN (get your teacher to organise one for your school – they’re great!) where the school would connect online to the ATLAS control room allowing the students to ask questions.

Once they’re setup, the schools can repeat the Masterclass programme every year, increasing the number of students who experience real research. This could eventually lead to their country becoming more involved in physics research!

My Interview

How would you describe yourself in 3 words?

Curious, happy, traveller.

Who is your favourite singer or band?


What's your favourite food?


What is the most fun thing you've done?

A helicopter ride over the Grand Canyon – it was amazing! But sky-diving and scuba diving are a close second and third.

What did you want to be after you left school?

An astronaut. (I still do!)

Were you ever in trouble in at school?

No, I was a geek! Fortunately I had some cool friends who kept the balance right and made me have fun.

What was your favourite subject at school?

Honestly, maths. But I also loved English and Drama.

What's the best thing you've done as a scientist?

Apart from my research, I did a stand-up comedy performance about being a scientist at CERN. 10,000 people watched it!

What or who inspired you to become a scientist?

Space – I really wanted to explore it! Also, my parents and some great teachers.

If you weren't a scientist, what would you be?

Probably a doctor. Unless the astronaut job came up :)

If you had 3 wishes for yourself what would they be? - be honest!

A time machine. A space ship. And to be able to speak any language. Hmmm, I think that’s a TARDIS from Doctor Who! Can I get two more wishes?

Tell us a joke.

A photon walks into a hotel. The receptionist asks if it has any luggage to take to the room. “No,” replies the photon, “I’m traveling light”.

Other stuff

Work photos:

I work at the Large Hadron Collider, also known as the LHC. It’s a 27 km ring in a tunnel that’s 100m underground which crosses the border between France and Switzerland. Protons, one of the particles that makes up the nucleus of an atom, are fired very fast (at almost the speed of light) in both directions around the ring. Then the protons are made to smash together at chosen places where all of the mess (the new particles) can be collected.


The photo above shows just how big the LHC is. You can’t see it in the photo (because it’s underground) so someone has drawn where it should be over the top. I work on the experiment called ATLAS, which has been labelled on the left.


The photo above is the ATLAS detector before they had finished building it. The grey and red striped tubes are magnets and they are used to bend particles with charge (like an electron, or its heavier cousin called a muon). Lighter particles bend more than heavier ones so this is one way we can find out what type of particle we are looking at. The man in the middle of the photo is there to show you how big it is!


Here is a drawing someone made to show all the layers of the ATLAS detector. Each layer does a different job in helping us to work out what new particles have been made from smashing the protons together. Can you spot the Tyrannosaurus rex? He’s there because it’s boring to always use people to show how big the detector is!


Here is the laboratory where I can test my pixel detectors. We put them into the fridge to the left (to keep them cold and in the dark) and we use the computer to the right to get information about how well they are working.


This is an experiment at CERN we did to test some new pixel detectors in a big beam of particles. In my hands I’m holding frozen carbon dioxide (also known as dry ice, because it’s not made from water). I’m wearing gloves because the ice is colder than −78.5 °C!! Water freezes at a cool 0 °C. We use this to keep our experiment very cold as the detectors work better at colder temperatures.

Around my neck you can see what looks like a blue necklace. This is called a dosimeter and it is used to keep track of how much radiation I get hit with. A little bit of radiation is not going to harm me, but too much could be dangerous for me in the future. (And just the right amount might give me superpowers! Or is that only in comic books..? 😉 )


When I’m working on my computer I can work anywhere with an internet connection. So sometimes I like to sit outside.


Because at sunset, this is my view!


Sometimes it can be useful to make a model of your experiment when it’s too big to take it to the people you want to show it to. And what’s better to build a model from than LEGO! Here is a LEGO model of the ATLAS detector I helped to build. It’s being signed by the scientist who came up with the theory of the Higgs boson, Professor Higgs himself! Last year he got the Nobel prize for this research.


I also spend as much time as I can talking to the public about the work we do at CERN. Here I am talking to a future scientist!


Thanks for taking the time to learn about what I do. Bring on the questions!! 🙂