The Nature of Antimatter

27th February 2018
peter talking to 5 universities

How lucky I am to have joined a collaboration whose 20-year developments have reached a tipping point in being published in Nature. Although I contributed to the data collection and development required to produce a paper accepted to Nature (to be published soon), and thereby having my name on it, it does feel like I am just in the right place at the right time, like I’ve grabbed onto the back of a racing car just before the finishing line. It is rare for a Masters student to be a listed author in a Nature article, but I’ll take it! It may prove to be very useful for a PhD application further down the line…

This week I spoke with five universities together on a video conference (from Sweden, Germany, Spain, Norway, and Slovakia) about both life at CERN and to discuss their analysis of some ATLAS data that was sent out to them a few weeks ago. CERN runs a programme where students have to make their own analysis on whether they have found the Higgs boson or not, using real data that was used to search for it. The hour-long video conference allows each university to see each other’s findings and hear each other discussing their interpretations. There was also a Q&A session when they asked what life is like at CERN and for any advice on how to start a project here.


Hopefully we inspired at least one to start thinking about applying for a research position in Particle Physics.

A few years ago I spoke with Marcus du Sautoy about how he would recommend becoming a science communicator. “YouTube is the way forward” he said, and my project to interview PhD students for a YouTube series will be my first attempt at following his advice. The project is, however, on hiatus until I learn how to take professional videos, with better illumination, framing, and noise reduction, and I shall make it a priority to speak to some audiovisual experts over the coming weeks so that these videos may have a better chance of reaching a wider audience. As this is the direction I would like to see myself going in, I need to train myself properly.


This training, of course, will happen outside the ALPHA working hours, where I have been busy making some boxes that protect very expensive parts of the experiment from spikes of high voltage. The idea is this: a wire inside a small box carries a normal voltage. If the voltage were to spike, there are two diodes (acting like dams) that activate and divert the current to earth, thus saving the instrument on the box’s output. There are two diodes just in case one of them fails, and there are two sets to allow protection from both positive and negative voltage spikes. A very simple device that has a very important function.

I have been working through the physics of how ALPHA determines the temperature of antimatter plasmas (how do you measure the temperature of something without touching it?) and developing some code that simulates how two different plasmas separate when they are mixed together. This is one of the main parts of my Masters thesis: using laser-cooled beryllium ions to ‘suck’ the energy from positrons (a process called sympathetic cooling) to make colder (and more trappable) antihydrogen. The plasmas need to overlap - we think - for this ‘theft’ of energy to take place, but they separate due to a centrifugal force produced by electric and magnetic fields, resulting in something like a sausage roll, where the ‘sausage’ part is the positron plasma and the ‘pastry’ part is the beryllium. Lower temperatures cause more separation, which is bad because the whole idea is to make colder positrons. I will soon be speaking with some professors across the world with expertise that may shed some light on this problem.


I bumped into the President of Austria today, literally, on the stairs out of the AD.


He was coming to see a pion detector that an Austrian university had made. This week CERN has had the head of state from Australia, Mozambique, and Austria. It’s great to see politicians visiting here, and having heads of state raises the profile, generating interest in their respective countries and sending the message that ‘Science Is Good’. It might do the USA a lot of good to get Trump over here.

My future as a scientist and science communicator will be on pause for a period of at least two years, when I shall be starting a new international boarding school in the south of China near Hong Kong. Something I realised while I have been working at CERN is that I take great pleasure in working with schools and tour groups of students, and I really miss the travel opportunities that international teaching has been able to offer. An income would be nice, too. The job, however, starts in August and my MRes finishes in September, resulting in an overlap analogous to that of positrons and beryllium. I will have plenty of time to think about what direction to look for a PhD in these two years, maybe looking out onto a Filipino beach drinking a cocktail, on a cramped train in India, or on some blustery Tibetan plateau milking a yak; who knows what the future may hold.