by Ian Randall. Published: 31 January 2011

This fortnight, ALICE Matters talked with Antonin Maire, a PhD student from the University of Strasbourg.

Antonin Maire

Hello, Antonin. What do you do in ALICE?

I work in strangeness, meaning the analysis of particles that contain at least one strange quark. More specifically, my specialty within strangeness is multi-strange baryons, called ? and ? so, particles which are heavier than a proton and hold two or three strange quarks (out of the three valence quarks).

What can we learn from studying strangeness?

In the context of flavour physics, we would like to understand the differences and similarities between up, down, strange, charm and bottom quarks.

The strange quarks sit in the middle of the picture: they are basically 30 times heavier than up and down quarks, but at least ten times lighter than charm and bottom quarks. This implies that they are rarer than up and down quarks, but still more abundant than charm and bottom ones. This intermediate status essentially justifies the interest in strangeness.

In practice, the good thing about strange quarks is the fact that they are transient. Any particle containing a strange quark will decay into several other more stable particles. We call these daughter particles. This feature is really a key point, from the experimental point of view, because this is what enables us to identify strange hadrons.

This identification capability works over a rather large energy domain: from low momenta to high momenta. It is then possible to address the particle production in different regimes. The bottom line is that strange particles may help to understand the physics that leads the production mechanisms - from the soft part of a collision to the hard part of it.

How did you get interested in the study of physics in the first place?

I came gradually into physics. When I was about 15, I had this feeling that physics would be the domain in which I would like to work. Little by little I made the choice to focus on a specific domain in physics, so I did my high school with a major in physics - and then I started to study at university, still in physics, and little by little, I came into particle physics.

So let’s say after three years of university I came to the idea that particle physics could be a good option. At the very beginning, I just wanted to be an astrophysicist, as I guess do many physics students, but then after making some investigations on what astrophysics is supposed to be, I noticed that it was not what I expected. And, then, I went from the big infinity to the smallest one - just the other way around. But there is a connection between the two!

What do you like to do in your free time?

Well, I confess that with the PhD, my hobbies are growing smaller with the fraction of time, but - ok, let’s say regarding sport - as soon as I have the opportunity to do it, I play tennis, in doubles. I also try to ride my bike, and do some mountain biking.

As for mental activities - I'm still interested in philosophy. I got this taste for it when I was in high school, where philosophy was a mandatory field of study. I still have a deep feeling regarding philosophy. I feel that it is necessary to wonder and question and I think that this is quite connected to science in the sense that you, as a scientist, are supposed to ask questions. So, in that sense, I really feel like philosophy and science are supposed to be close to each other.

What are your plans for the future?

You mean after the PhD? At the moment I still intend to stay in research, so I will go for a postdoctoral position. Basically, I hope to stay in ALICE.



Nice to meet you!

I think these posts are a great idea. It's nice to be introduced to the faces behind the magic :)

Just one question: what are the hard and soft parts of collisions? I think it is interesting that you chose to focus on this area as it at first seemed to be quite limited. Good luck with your PhD!


re: hard and soft parts of collisions

Thanks for the comment.
To answer your question: "what is the soft part and the hard part of the collision ?"
When a high-energy collision occurs, in most of the case, we produce particles out of the initial system.
Let's take the collisions of 2 protons or 2 lead ions at the LHC, for instance. At such an energy level, a collision spawns, say, ~5 particles on average in proton-proton events, and up to ~1500, in lead-lead.
Among those newcomers, we can sort out the "soft" particles from the "hard" ones. The first will be the most frequent and numerous but each of them will carry just a small fraction of the total energy; the second ones will be scarcer but more energetic.
It is a question on how the energy released by the collision is distributed among the new population.

Antonin Maire

I, too, enjoy being able to

I, too, enjoy being able to connect human faces with the work. As a non-professional and non-mathematician, the concepts in particle physics are necessarily extremely fuzzy to me, almost like philosophical concepts! I think of research physicists as being like eight year olds discussing geography, and an interested lay person like myself is like a five year old listening in awe.
Thank you and best wishes in your career.