Tag Archives: CERN

Test Beams

The last ten days or so I’ve spent at CERN testing new designs of pixel detectors for the ATLAS experiment. Since it was the IOP’s #iamaphysicist event on the same day we were setting up, I tweeted out the following picture.

To measure our pixel detectors, we need a beam of particles from a particle accelerator. Fortunately at CERN, we have many to chose from! Just see the diagram of all of the accelerators required to get the protons to the LHC. Our experiment uses the SPS, or Super Proton Synchrotron, the last accelerator in the chain of accelerators which feed the LHC with protons. The protons enter the SPS at 25 GeV and are accelerated up to 450 GeV (note the LHC accelerates to 7500 GeV, or 7.5 TeV, per beam). We then use a target to change the type of particle from a proton to a pion.

The LHC is the last ring (dark grey line) in a complex chain of particle accelerators. The smaller machines are used in a chain to help boost the particles to their final energies and provide beams to a whole set of smaller experiments, which also aim to uncover the mysteries of the Universe.

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First 13 TeV Collisions with stable beams at CERN

Last Wednesday, the Large Hadron Collider at CERN started colliding protons with stable beams at the highest energy we’ve ever achieved! I had a very early start (alarm went off at 5.30am) to be in the ATLAS Control Room and tell everyone all about it on social media through the ATLAS Twitter accounts. There was a team of us from ATLAS Outreach working that day.

Even at 8am, it was standing room only as so many people wanted to see the first stable beam collisions at 13 TeV.

CERN had a live webcast to explain what was happening and at one point, when checking it, I realised I was live in the background of an interview with ATLAS Spokesperson, Dave Charlton. So, I acted natural and was thankful that, even though I was supposed to be doing the social media, I wasn’t on Facebook.

Me on the CERN webcast.
Me on the CERN webcast.

A little before 9am, the beams that had been increasing in energy inside the LHC were dumped and they had to start again. No problem, as it’s essentially a new machine, this was not unexpected. Everyone went to get coffee and breakfast (or second breakfasts) and I updated Twitter:

Continue reading First 13 TeV Collisions with stable beams at CERN

CERN Dishwasher

While I was curating the @RealScientists account and generally being a tourist at work around CERN, I snapped a photo of dishwasher that was being used to clean a readout board I needed for my test beam experiment. I put the photo up on Twitter and it got a little bit of attention. The photo was spotted by CERN, and yesterday Rosaria Marraffino wrote a CERN bulletin article about the dishwasher. It seems to be a very popular image as only a day later it’s already amassed over a thousand retweets on Twitter! Here’s the tweet (below) and a link to the article.

Real Scientists

Last week I was the curator of the Real Scientists Twitter account (@RealScientists). It coincided with a trip to CERN for a test beam experiment so I took full advantage of being on site to show as much of CERN as possible. I ended up having a lot of fun being a tourist in my own lab and got to see parts of the site I’d never been to before! It started off a little slow as I found my feet with a new (to me) account and as I prepared for my trip, but everything really took off Tuesday morning when I landed in Geneva.

I wanted to include as many photos as I could, to allow people to feel like they were really visiting the lab. The following was a very popular image (but please excuse the typo, the WWW was invented just *over* 25 years ago).

I also talked about my preparations for the experiment at CERN, including a bit of shoe-shopping!

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Maths at CERN

A few months ago I took part in a recording of a podcast about some of the different mathematical techniques used at CERN. Specifically, the podcast was looking at A-Level maths used by people in different careers and the aim was to inspire school students to study the subject in the UK.

The first example that came to my mind when I thought about where we use maths often was sigma, which is written with the Greek letter σ. This is the value you will often hear particle physicists use to describe how confident we are with the result and was mentioned a lot during the announcement of the discovery of the Higgs boson in 2012. One sigma (or 1σ) is the standard deviation of a distribution of numbers and roughly 66% of the numbers should fall within it. For the announcement of a new particle, we use the criteria of 5σ, which tells us that there is a 1 in 3.5 million chance that, if the Higgs didn’t exist, we would still get this result.

I also talked about how the theory of antimatter came about. In short, when Paul Dirac was attempting to combine quantum mechanics (the world of the very small) with special relativity (the world of the very fast) into a single equation. His equation had a squared number in it, specifically for the energy term, and to solve it he needed to take the square root. From maths we know that the square-root of a number can either be positive or negative. But can you have negative energy? Dirac thought not, and the only other way to solve the equation was to introduce an entirely new set of particles with the same properties as those we already have, but with the opposite charge. This is what we now know as antimatter. Only a few years later, Carl Anderson made the discovery of the first antimatter particle with his famous bubble chamber experiment!

Positron Discovery

Yesterday the episode of the podcast with my interview was released and you can check it out at the following link, look for “Episode 5: CERN and standard deviation”


At the end of each podcast, they give a puzzle. The one for this episode is:

Puzzle: The heights of a group of people are measured, and the resulting data has mean 1.35m, and standard deviation 0.13m. Someone in the group is 180.5cm tall. How many standard deviations away from the mean are they?

Can you work it out? Leave me a comment with the answer below! I’ve been mean and not given the solution, so if you want to compare your answer with theirs, you’ll have to head to the link above.

Comedy Collider: No Cause for ConCERN

On Friday the 13th of June the Comedy Collider team hosted our second show at CERN’s Globe of Science and Innovation. The seats were once-again completely sold-out before the day of the event, and the waiting list was only growing, so we we looked forward to a good crowd. We’d enlisted a entirely brand new set of amateur and professional comedians to entertain for the evening, including Spain’s The Big Van Theory and The Spoken Nerd’s Helen Arney providing musical meekness! Our host for the evening was Chella Quint. The CERN amateurs taking to the Comedy Collider stage were Nazim Hussain, Cat Demetriades and Aidan Randle-Conde and they were all brilliant!

Unfortunately we had competitors for the online audience that night: Spain vs The Netherlands in the 2014 Mens Football World Cup. We can’t really blame people for wanting to watch the game, so we’re sharing the link to the show, available to watch online now, or any time you like – just click below. Enjoy!


You can also view a storify of the event, here.

Zombies at CERN

Not everyone who knows me, knows that I like horror films, but I do! In fact, I’m a particular fan of zombie films. I’m such a fan, I even made a feature length one with fellow zombie-loving physicists a few years ago at CERN! Our film is called Decay, and it’s named because decay is a word that is appropriate for both the zombie world and the particle physics one (when heavier particles change into lighter ones we say that they decay). It also conjures up images of nuclear decay and a lot of zombie films used radiation as their undead trigger. We were the first ones (as far as we know) to suggest that the dead could rise because of Higgs bosons created at the LHC at CERN! To learn a little more, I’ve added the trailer below.


We have to be clear that the film has never been endorsed by CERN, since it does have some questionable senior characters. But, they also didn’t shut us down, which was great! Since being released for free online less than two years ago, we’ve had almost four million views on youtube! It just goes to show how much people love (a) zombie films and (b) CERN, especially when it’s the two together!

So where’s the science in all of this you might ask? Well, there isn’t any. At least, we made it all up! We wanted to make fun of all those films with pseudo-science in them so we filled ours to the brim with bio-entanglement physics!

Clara in Decay
Screenshot of me in Decay, filmed at CERN in 2012.

I’ve added some screenshots from my moments of stardom in the film (two), although I was actually on-screen a lot more often than you might think, or at least on the set making something happen. As well as pensive physicist and later rampaging zombie, known affectionately as ‘Bitey‘, I also played a computer and a spray of blood.

When I wasn’t in front of the camera, I was on set doing something else. We were all amateurs on the film, so there was a lot to do and learn. One of my many hats on set was assistant director and one scene I was able to have a lot of control over was the ‘horde scene’ near the end of the film (which incidentally was my favourite one!). It was this scene where I had to ask roughly 50 physicists, all of whom had volunteered as zombie extras for us for the day, if any of them knew if they had a latex allergy!

Screenshots of me in our feature-length independent zombie movie filmed at CERN in 2012.
Screenshot of me in Decay, filmed at CERN in 2012.

The film got a lot of fantastic media coverage from all over the world! My favourite article title was: “Why a Zombie Movie Made by Physicists is the Best Kind of Science PR” in Slate. Occasionally someone will tell me about the film (unaware that I was involved) and it makes me really happy that people enjoyed it and are still talking about it!

I had a fantastic time making the film (in between the 13 hours sitting in a dark damp tunnel covered in red-coloured maple syrup that is!). I also think it’s awesome that I have an IMDb page and that we worked out we each have a defined Erdős–Bacon number of approximately 11!

A screenshot from my IMDb page.
A screenshot from my IMDb page.

If you want to watch the whole film, I’ve embedded it below! You can also leave me a comment to let me know what you think! (with a kind reminder that it’s a low budget horror movie made by amateurs! 😉 )

Oh, to prove that we actually had a lot of fun making the film here are some out-takes:

And the edited version of our Q&A session at the International and UK premiere of Decay in Manchester.