This week I’m in Windsor Great Park for a summer school on Monte Carlo event generators for particle physics (and beyond).
UCL is organising this as part of the MCnet training network, funded by the Marie Skłodowska-Curie actions of the European Union. (It is a relief that the school is still being held in the EU, that did not seem likely when we started organising it.) We have about fifty PhD students and postdocs from around the UK, the rest or Europe and the world, here to learn (and teach) about Monte Carlo event generators in particle physics and related topics.
As I write, Stefan Gieseke from Karlsruhe is giving the opening lecture, introducing the basic ideas. Monte Carlo event generators are there to produce simulated particle physics “events” – the result of a collision between a single pair of particles.
These “events” have to be generated according to the theory that is being tested, and that usually means they must follow a highly complex function, based on the underlying interaction and the available phase space. The best way to do this is to sample random numbers and accept or reject them according to how likely the theory says they would be. (This dice-rolling element is behind the name “Monte Carlo”, of course.) You can maybe get the idea from Stefan’s slide below.
The points on the right are generated randomly, and accepted or rejected according to whether they are above or below the red line (which could be an arbitrarily complicated theoretical function). Counting the number of black (accepted) points versus orange (rejected) points gives the total probability, or cross section, for the events, and the black points are distributed according to the theory function. The events we generate can then be compared to data from actual collisions, to see whether the theory we are using is correct or not.
Before Stefan began, we had a talk from the programme director here, Dr Jan-Jonathan Bock, about the history and purpose of Cumberland Lodge and the trust that runs it. The Lodge was granted by King George VI in 1947 to a new educational foundation established by Amy Buller. She had recently published her groundbreaking book, Darkness over Germany, about the rise of Nazi sentiment amongst students and academics in Germany in the late 1930s. Part of the mission of the trust is to provide education, dialogue and inspiration, especially to students, to try and make similar events less likely in the future. I hope it is working. It does at least seem that the current delusional nationalist drift in UK politics is mainly driven by the elderly, not by the young, so perhaps there is hope.
(By the way for anyone reading this thinking “Oh he’s funded by the EU that’s why he is against Brexit…” No, nope, that’s really not it. Also I don’t get any of the money personally.)
Anyway, the sun is out and I am looking forward to the rest of the week. If you are are a particle physicist reading this and thinking “Damn, missed it”, we are running something similar in Vietnam in September, and you can still register.