Niels Doble (1938–2026)
—
Niels Doble, born on 2 May 1938, passed away on 8 August 2026 after a short illness. Niels was best known for his pivotal contributions to the initial design and subsequent operation of the North Area at the Super Proton Synchrotron (SPS) complex.
Niels studied physics at the University of Bristol. After a year at the Niels Bohr Institute, he joined CERN in 1962 and worked on hyperon polarisation in Bill Lock’s emulsion group. In 1968 he earned his PhD at Bristol under Don Perkins, before moving to the Max Planck Institute in Munich, where he worked on the Hyperon Bubble Chamber (HYBUC) experiment and on a 15 T normal-conducting magnet. It was also in Munich that he had previously met his wife, Gunilde, whom he married in 1966.
In 1972 Niels joined Giorgio Brianti’s group at CERN, focusing on the design and construction of the North Area and essentially shaping its layout. By the end of 1974, he had already written the conceptual design paper with Roger Clifft for the M2 muon beam, which was commissioned in 1978. Niels was Group Leader of the Experimental Areas Group and a member of the Super Proton Synchrotron Committee (SPSC) from 1979 until the end of 1991.
Niels participated in several important experiments, including NA20 in 1980, which studied particle production, and NA30 in 1985 on the neutral pion’s lifetime. Users of the North Area remember well the exceptional support that he provided over the years. Through his advice, written notes and willingness to listen and explain, Niels mentored the next generation of beam physicists.
While still ensuring excellent support across all beam lines, Niels later focused on beams for the kaon programme, starting with the NA31 experiment in Experimental Hall North 1, for which he designed the 20-metre-long train that moved the KS production target station across 41 positions inside a large vacuum tank. In 1998, the experiment showed the first evidence for direct CP violation.
In the follow-up experiment, NA48, Niels was instrumental in providing simultaneous, almost collinear KL and KS beams. This was made possible by the pioneering use of a bent crystal to transport the required small fraction of protons from the KL production target to the KS target. Niels coordinated the production of the crystal, its bending mechanism and a goniometer in collaboration with outside institutes. The experiment led to a 7s observation of direct CP violation in the Ko system.
After his retirement, Niels continued making vital contributions to the K12 beam line and the NA62 experiment. He remained actively involved in beam operation and in the experiment until the very end.
In his free time, Niels loved music, skiing, snowshoeing, hiking and swimming. Niels was a generous, genuinely nice and approachable person, and a gentleman. He earned widespread respect through his thorough, deep approach to both physics and life, and we continuously benefited from his quiet wisdom, calmness and authority. Niels was both a key figure for the kaon programme and the North Area as a whole, and a friend. He will be deeply missed.
Our thoughts are with his son, Michael, and his daughter, Karin.
His colleagues and friends
An obituary will also appear in the CERN Courier.