High Energy Physics postgraduate personal statement example

Personal statement example

For the first fortnight of my final-year project, the Upsilon resonances were missing from my plots. I was reconstructing the invariant mass of muon pairs from a CMS open data sample, and the J/psi peak near 3.1 GeV was obvious. Around 9.5 GeV, however, there was only a gentle rise. The problem was my choice of bins. They were wide and evenly spaced, so they smeared three closely spaced states into one lump. When I switched to logarithmic binning and narrowed the range, the Upsilon(1S), (2S) and (3S) peaks separated. That moment taught me more about the gap between data and physics than any lecture had. It is also why I want to pursue postgraduate study in high energy physics.

The project grew from that start. Working in Python with the uproot and awkward libraries, I applied quality cuts to the muons and required opposite charges. I then compared how much the spectrum changed when I tightened the transverse momentum threshold. Fitting the Z boson peak was the most satisfying part. A simple Gaussian fitted badly, and I had to learn why the Breit–Wigner shape, convolved with detector resolution, describes the data far better. My supervisor encouraged me to estimate how sensitive my fitted mass was to the choice of fit range. Writing that up honestly, including the parts I could not fully explain, was harder than producing the plots.

My degree gave me a solid grounding for this. I enjoyed my nuclear and particle physics course most. Alongside it I worked through much of Griffiths' Introduction to Elementary Particles, especially the chapters on Feynman rules and on quantum electrodynamics. Working out simple scattering amplitudes by hand helped me see where the cross-sections I took for granted in the data actually come from. My weakest area is quantum field theory beyond an introductory level. I have started reading lecture notes on canonical quantisation, but I expect formal study to be demanding, and I want the structure of a masters course to take me through it properly. I am equally interested in the experimental side, particularly detector response and how reconstruction choices propagate into a final measurement.

Outside my studies, I have worked Saturdays in a bicycle repair shop for three years. Most of the job is routine: replacing brake pads, fitting tubes, truing wheels. Truing has made me patient with small, repeated adjustments where tightening one spoke shifts the rim somewhere else. The owner now trusts me to open the shop alone and to explain repair estimates to customers, which has made me better at giving clear explanations without jargon. I also play tenor horn in a local brass band. Rehearsals are not a scientific activity. Still, sitting in a section and listening across the room for balance has made me comfortable as one small part of a large, coordinated effort. That seems a fair description of work in a large collaboration.

I am applying for postgraduate study because I want to move from reproducing known peaks to understanding why the analyses behind them are designed as they are. I would like to learn the theory well enough to follow the reasoning behind a search, not just the code. I also want to gain experience with full simulation and systematic uncertainties, which my project only touched on. In the longer term I hope to continue to a doctorate in experimental particle physics. Before then, I know there is a great deal to learn. I would bring careful programming habits, a willingness to question my own plots and steady persistence when a result does not look right the first time.