Former Nikhef physicist Michiel Botje passed away

26 April 2024

Retired Nikhef researcher Michiel Botje has died in France after a short illness. This was announced Thursday by the family.

Michiel Botje in 2003.

Botje was associated with the ALICE experiment and Utrecht University, where he had studied physics and received his PhD, until his retirement in 2014. Before that, he worked at the ZEUS group at Nikhef and at DESY in Hamburg, and NA49 at CERN, among others.

In Utrecht and at Nikhef, Botje was considered a dedicated and helpful teacher in the fields of quantum chromodynamics and (Baysian) statistics. His lecture notes have been used as teaching material by generations of physicists. He was a co-promoter for a large number of physicists in the field during his career.

His last publication was in January 2024, on the internal structure of the proton. Even after his retirement, he was closely involved in the development of the computer program QCDNUm for calculations in quantum chromodynamics. That program played an mayor role in the design of experiments at the LHC accelerator at CERN.

ALICE program leader Raimond Snellings of Nikhef and the UU wrote a short in memoriam for Botje.

In memoriam Michiel Botje (1948-2024)

On Tuesday the 23rd of April Michiel Botje unexpectedly passed away after a short sickbed. Michiel Botje was a senior experimental physicist at Nikhef working at experiments at CERN, Brookhaven, and DESY in the fields of deep inelastic scattering and heavy-ion physics. After he finished de “Hogere Zeevaartschool” and was briefly an officer in the Holland America Line for deep sea shipping he started his scientific career at the CERN ISR as a PhD student working with Hans Sens. He continued his career after his PhD in the New Muon Collaboration working for the Paul Scherrer Institute (PSI) in Switzerland after which he moved to Nikhef working in ZEUS at the Deutsches Electronen-Synchotron (DESY). During this time, he made leading contributions to the measurements and interpretation of the momentum transfer dependence of the structure functions and parton distributions. When the DESY program stopped he started working on heavy-ion collisions, first at CERN in the NA49 experiment, later in the STAR experiment at Brookhaven National Laboratory and finally he became a valued member of the CERN ALICE experiment at the large hadron collider.

For the Nikhef LHC effort Michiel helped setup the DataGrid for ALICE and the ALICE Tier-1 in the Netherlands. This effort helped make sure we could process the overwhelming amount of data that was coming out of the LHC experiments in which Nikhef participates.  Michiel also was one of the pioneers of using Bayesian Inference for data analysis. His lecture notes on the Introduction to Bayesian Inference are still a reference for students wanting to understand the difference between the Frequentist and Bayesian approaches. It gave Michiel great pleasure to see that in the last decade the field moved more and more to using Bayesian inference for complicated many parameter problems. 

Michiel’s life work was the very fast QCD evolution program which solves the DGLAP equations in NNLO for unpolarized and in NLO for polarized particle distribution functions and fragmentation functions. He retired from Nikhef in 2014 but continued to work on his QCDNUM program. The most recent version of the program was released in 2022 and Michiel’s last scientific publication was released in January of 2024 where he introduced a novel Bayesian parton density determination code.

Michiel loved to work with younger colleagues throughout his career and was an inspiring teacher. As a lecturer he explained master students, at Utrecht University and Nikhef, the mysteries of QCD and his very clear lecture notes are still used by many all over the world. The work of Michiel is characterized by his meticulous approach to all off the aspects of teaching and research. He was well known for his high-quality scientific output and was always ready to help his colleagues to significantly improve the clarity of their papers and the logic of the arguments.

We remember with great respect Michiel Botje, as an excellent scientist, inspiring teacher and great colleague who was always ready to help. We wish the family, and particularly his wife Martine all the possible strength in coping with this big loss.