A solid engineer for a lineage of colliders.
It is with great sadness that we learned that Sigmund Hansen passed away on 21st August 2026 at the age of 94.
Sigmund was born in Nøtterøy, Norway. He graduated from Engineering School in Oslo, then completed military service with the Norwegian air force. He joined CERN in 1957, with the Accelerator Research group. He developed highly specialised electronics for the CERN Electron Storage and Accumulation Ring (CESAR) – a demonstration prototype for the future Intersecting Storage Rings (ISR)
With the approval of the ISR project, Wolfgang Schnell asked Sigmund to join the newly formed ISR-RF group. Sigmund played a key part in the design, construction and commissioning of low power RF and beam control systems for the ISR. This
included the crucial phase lock systems for the capture and acceleration of the injected beams, as well as novel diagnostics systems for measurement of betatron tune and beam frequency.
ISR was the world’s first hadron collider. During its 13 years of operation till 1984, it achieved record luminosities and made many ground-breaking discoveries and developments in accelerator physics. The RF group, under Sigmund, initially as deputy then group leader from 1979, contributed significantly to this work, notably including Schottky noise, control of microwave instabilities and stochastic cooling. These were to serve with fundamental importance in a succesion of future accelerators, both at CERN and worldwide.
With the approval of LEP in 1983, the group became the LEP-RF group, under Wolfgang Schnell with Sigmund as deputy. Prototyping of equipment needed for the enormous LEP RF system – 128 cavities, 16 high power RF klystrons and the associated low power and controls equipment was soon under way. Sigmund coordinated the construction of test stands and directed negotiation of large outside procurement contracts. He played a major role in the installation and commissioning of the LEP RF system.
Sigmund was an excellent leader. He managed in an open, communicative and friendly style. He readily provided encouragement and support to colleagues. He enjoyed organizing and participating in many of the RF group’s social activities. He was keen on sports and was an excellent skier, both cross-country and downhill. With restructuring in the early 90’s Sigmund stepped back, leaving technical responsibilities to younger members of the group, but he kept a strong interest in the ongoing progress of LEP.
Sigmund retired in 1996, but he maintained contact with former colleagues, right up till the very end. He will always be remembered for his achievements and for his open, friendly personality. It was a great privilege to have known him and to have
worked with him.
Our deepest sympathy to his daughter Isabelle and to all the family.
His former colleagues and friends