James Stirling

Today I got the terrible news of the untimely death of Professor James Stirling. A distinguished particle physicist and until August the Provost of Imperial College London, he will be remembered with fondness and admiration by many.

Even astronomers – Peter Coles has posted more about why here. In particular he writes:

Professor James Stirling was one of the leading lights of the Institute for Particle Physics Phenomenology in Durham (of which he was the first Director) and subsequently became Jacksonian Professor of Natural Philosophy and Head of the Cavendish Laboratory at the University of Cambridge. More recently he was Provost of Imperial College, a post from which he stepped down earlier this year. He was elected to a Fellowship of the Royal Society in 1999, and awarded a CBE in the New Years Honours List in 2006.

All true and important, but there is obviously much more and I want to add some.

I’m pretty grumpy about role models and (often unjustifiably, I think as I get older) harsh on my senior colleagues, but James was someone I looked up to and admired from very early in my career as a particle physicist. Probably from the very start, since he was the “S” in the MRS parton distributions (Alan Martin and Dick Roberts being the M and R). These were one of several widely-used parameterisations of the quark and gluon content of the proton.

I did my PhD work on the HERA electron-proton collider. The main job of HERA was to measure these things. MRS D0 and MRS D- were two qualitatively different models. As you probe smaller fractions of the momentum of the proton,  D0 had a flat distribution of gluons and in D- they rose rapidly. The question of which would be closest to nature was  hotly debated. It turned out they went up pretty quickly (as also sort-of-predicted from QCD by Glück, Reya and Vogt), and this does tell us important things about the proton and the strong force. “The initials”, MRS, GRV and others, were rock stars for nerdy particle physicists on HERA. Some of us used to “collect” them, ie tick them off a list when we met them. Allegedly.

There was much more though. James was friendly and modest, and always had time for people (even mouthy students with naive questions). He was often just the most grown up, nicest person in the room when things got heated. His book with Keith Ellis and Bryan Webber is a pre-LHC classic on what we needed to know and do.

I was one of the people moving from HERA to the LHC, and was part of the organisation of a series of workshops addressing how to make best use at the LHC of what we had learned at HERA. Since the LHC collides protons together, and HERA told us what was in them, there were many obvious connections, but clarifying them was a challenge. There is one plot from these proceedings which still appears in particle physics physics PhD theses even now (in fact in one I examined just last week) and it is from James:

kinematic plane

By James Stirling, from https://arxiv.org/abs/hep-ph/0601012

I’m aware the explanatory power of this plot won’t leap out at you unless you are a particle physicist, but trust me, for a particle physicist this is a masterly and clear translation between the kinematics of an electron proton collider and a proton-proton collider. It is so widely used that I suspect lots of people who include it in their presentations don’t know it was made by James; so now you do.

James and I were co-Principal-Investigators on a little “eScience” grant called CEDAR (Combined E-Science Data Analysis Resource) which, courtesy of Susanna Butterworth (relation), Andy Buckley and James Monk who were funded by it, led to hepforge, rivet and some other cool stuff you may have come across if you are in the field. CEDAR lives on as part of MCnet, at least until… no, I won’t go there now.

James was the first head of the Institute for Particle Physics Phenomenology at Durham. I was very honoured to give the Stirling lecture at Durham in 2016. The fact that the ridiculously busy, famous and in demand Director General of CERN, Fabiola Gianotti, gave the lecture last year gives you some idea of the regard in which James was held.

That’s a partial account of some of my interactions with James; and that one plot is obviously a tiny fraction of his contributions to science and the academic world. It was brilliant working with James and I will miss him. To his family and others who knew him much better than me, my deepest condolences.




About Jon Butterworth

UCL Physics prof, works on LHC, writes (books, Cosmic Shambles and elsewhere). Citizen of England, UK, Europe & Nowhere, apparently.
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