With great sorrow we learned that on August 28, after a short period of sickness, at the respectable age of 90 years, our friend and colleague Bert Diddens passed away. He was one of the old veterans in CERN’s proud history of particle physics and the first scientific director of the Dutch high energy physics institute NIKHEF.
Bert was born in the province of Groningen, in the north of the Netherlands, a region where people tend to be straightforward, down to earth, matter of fact and Bert fitted that description very well up to his last days when telling his family that he didn’t want flowers at his funeral, as the money could be better spent on science. But behind this demeanor he was a gentle and sensitive person, loyal to his friends and colleagues. Up till his last days he remained interested in the sciences, visiting regularly the Nikhef library to stay informed. And that he remained informed was illustrated by his always to the point comments, when the jury, consisting of all other former Nikhef directors, deliberated on what was the best PhD thesis of the past year.
Bert studied physics at the University of Groningen, where he also received his PhD. The experimental work that led to it, however, was done in Leiden, where he studied gamma radiation from oriented Cobalt and Manganese nuclei using low temperature techniques. After his PhD he joined the small group of physicists in Liverpool that did the warming up -before the CERN laboratory was established- for CERN’s first experimental programme. He worked there on proton-proton scattering at the university’s synchrotron, a topic that remained a thread in his early experimental career. In 1963 with Giuseppe Cocconi and Alan Wetherell, later joined by Jim Allaby, he formed a group to study proton-proton scattering at the PS. The experiment revealed that the slope of the diffraction peak shrinks with increasing energy. A few years later with Alan and Jim he initiated an experiment at Serpukhov to study particle production and the total hadron-hadron cross section at the then highest proton energy of 70 GeV. In 1970, with the ISR being constructed, Bert with his CERN colleagues joined Ugo Amaldi and Giorgio Matthiae of the Rome-ISS group to design an experiment to study small angle pp scattering, introducing a novel technique, later known as “Roman Pots”. Just before he was asked in 1975 to become the first scientific director of the high energy physics section of Nikhef, he turned to neutrino physics, when his CERN team joined Klaus Winter in the CHARM (CERN-Heidelberg-Amsterdam-Rome-Moscow) experiment.
As director of Nikhef he was responsible for shaping its first experimental programme of which CHARM, no surprise, became a valuable part. As Nikhef had not yet its own building he was the person with the responsibility to make sure that the design and construction of a new laboratory fitted the ambitions of the Dutch high energy physics community. The success of today’s Nikhef is to a large extent determined by these first developments. When Nikhef had to decide which LEP experiments to join, it was obvious that Delphi would be one of them, extending into the LEP era the amicable bonds with his former CERN colleagues. He actively participated in the experiment after his directorship came to an end in 1983 and was the thesis supervisor for many PhD students of both Delphi and CHARM.
We all remember Bert Diddens with the greatest respect as a wonderful person, an excellent physicist and a key person in establishing Nikhef as an important player in the international community of high energy physics institutes.