Fred James (1939 – 2026)
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Fred James, CERN’s renowned expert on data analysis and statistics, pioneer of numerical methods, and co-author of the popular book Statistical Methods in Experimental Physics, sadly passed away on 31 July.
Fred was born in Detroit, USA, on 28 May 1939, and graduated in 1960 from Princeton University with a degree in physics. He earned his PhD from Yale University in 1965, researching strangeness production in pion–proton reactions at Brookhaven National Laboratory under the supervision of Henry Kraybill. Soon after, he joined CERN, where his deep affinity for mathematics placed him at the vanguard of numerical analysis techniques in high-energy physics.
By the late 1960s, Fred was already deeply involved in particle physics simulation techniques. His early notes evolved into his definitive review article, “Monte Carlo theory and practice,” published in Reports on Progress in Physics.
Fred also authored a number of mathematical algorithms in the popular CERN Program Library (CERNLIB). Recognising the need for robust numerical methods for function minimisation, Fred worked with Matts Roos to develop MINUIT, first written in the era of punch cards and FORTRAN. MINUIT quickly became a standard function minimisation algorithm across particle physics and beyond, and remains a fundamental optimisation tool used for the majority of results published by the LHC experiments. In particular, it was the backbone to computing the discovery significance of the Higgs boson. Fred also developed MINOS, an essential tool for the statistical interpretation of the likelihood function near its minimum and for computing confidence intervals and regions.
Alongside William Eadie, Daniel Drijard, Matts Roos, and Bernard Sadoulet, Fred wrote Statistical Methods in Experimental Physics in 1971, a widely influential authoritative treatise for researchers. Fred later gave the book new life by publishing a thoroughly updated edition in 2006.
In January 2000, Fred, Louis Lyons, and Yves Perrin organised a landmark Workshop on Confidence Limits at CERN, where physicists and statisticians dove deep into contentious methodological questions. This successful initiative sparked the PHYSTAT workshop series, which continues to flourish today.
Fred’s work on Monte Carlo methods naturally extended to pseudo-random number generators. In the 1990s, he developed and promoted RANLUX, a generator implementing Martin Lüscher’s high-quality random number algorithm. It has since seen thirty years of intensive use in different branches of science. After retiring in 2004, Fred collaborated with Lorenzo Moneta on investigating pseudo-random number generators based on dynamical systems, culminating in a 2019 comprehensive review paper.
Philosophically, Fred was a strong advocate for the frequentist interpretation of probability, vigorously championing this principle throughout his career and retirement.
He firmly maintained that scientific progress is driven not by Bayesian decision theory with its subjective degree of belief, but by objective inferences rooted in frequentist traditions.
Fred was always available for discussions, and many of us enjoyed his friendship and his generosity. His computational tools, many discourses and insistence on statistical precision have shaped the analytical toolsets of generations of researchers and will continue to guide scientific discovery for years to come. He will be dearly missed, and our thoughts are with his daughters, grandchildren, friends and colleagues at this difficult time.
His friends and colleagues