Making a switch: From theory to experiment

I have a postdoc contract in particle physics. Specifically, I work in an experiment that studies the nature of the neutrino, one of the most elusive particles in the Universe. But, how did I end up here? Let’s start from the beginning.

PhD in theoretical physics.-

As the day of my graduation (in physics, particle phenomenology) was approaching, I started thinking about doing a PhD. I was not sure about the academic career but I wanted to give it a try, especially since I was not interested in any particular job that a degree in physics could have offered me. Since mine was not a clear vocation for research, I decided to try to combine the PhD with an experience abroad, in order to earn more experience beyond the research per se, such as the knowledge of a foreign language. The specific topic wasn’t that important for me, but I wanted to stay within particle phenomenology. I had a look around and, partly for deadline reasons, partly for affinities, I decided to apply to PhD programs in Spain and I got a fellowship from CSIC (the Spanish research council) to work on high energy QCD.

During my PhD I studied, at first, calculations of n-particle amplitudes, using techniques alternative to Feynman diagrams: they were very long analytic calculations and I would spend hours staring at an expression, hoping to have a brilliant idea which could help to simplify it. After that, I passed to more “concrete” physics, calculating amplitudes of top quark production in accelerators, such as Tevatron and LHC.

I obtained the PhD title, but, despite this, I was convinced that continuing with that type of work was not for me, for two main reasons: on one hand, it was far from reality. Calculating mathematical quantities based on a model, changing a variable or two, with the hope that the result would predict experimental data, was not very gratifying. On the other hand, the daily work (mainly calculations by hand or with the help of programs such as Mathematica and, sometimes, Monte Carlo simulations with Fortran) turned out to be extremely monotonous and boring. All of this contributed to lower my motivation.

Becoming an experimentalist.-

Thus, in the end I decided to change field. Particle physics was still attractive to me: it deals with one of the fundamental questions of Man: “What are we and Nature made of?”. For this reason, I didn’t want to leave research and I had a look in the experimental area. In my institute there is a group doing medical physics and I found out that there were several people with PhDs in theoretical physics that later changed to a more applied field, such as imaging in medical diagnosis. Therefore, a background in maths could be useful, after all! At the same time, I talked with people from experimental particle physics and I got in contact with neutrino physics. In the end I decided to work in this group, starting with a contract as a student that, soon after, would be upgraded to postdoc.

  • What is my job?
    With my background I started working on software. I simulate the detector and the physical processes that occur there, in order to make predictions to compare with data. In addition, I analyze both real and simulated data. The parts of my work which interest me most are developing my own code within a framework developed by myself and my colleagues and testing it on our own data without having to rely too much on external influences and that I can now see a clear application of my day to day work which really satisfies me. I understand that the simulations I do are essential for the understanding of the experiment.
  • What did I have to learn?
    The change has been big, without a doubt, I had to learn a lot from scratch, often feeling like a student at the beginning, especially regarding programming (we use a lot of C++ and Python, which I had not used before) and detector physics, which I had just some basic knowledge about.
  • How was my previous experience useful?
    My four years of PhD provided me with experience in the academic world, in speaking in public in conferences, in presenting my work, in writing articles. A theoretical formation allows you to understand also the more abstract sides of the models that describe the physics you work on and the wider view that it gives you is of help to the motivation. Furthermore, the PhD prepared me to face difficulties and the moments of discouragement that appear sooner or later. I knew that they would come, more than once and that they can be dealt with and overcome. This has allowed me to work in a more efficient and faster way.

As a whole, I have to say that I’m satisfied: my daily work is varied and results arrive faster. I also think that working in a group makes days more interesting and dynamic, compared to the one-to-one relationship usual in theoretical physics. It allows you to have a greater exchange of knowledge and you have the possibility of learning from more people. There are also drawbacks, of course: you are more demanded and you need to learn to work as a team and to work out tensions and arguments.


One thought on “Making a switch: From theory to experiment”

  1. Hi, I was wondering: how many experimental physicist in your group actually did a PhD in a theoretical field? Is it common and easy to switch from theory to experiments in particle physics? Would you recommend to start a PhD with a theoretical focus if your interested also in the experiments?

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