Simon van der Meer
1925–2011, The Hague, Netherlands, Geneva, Switzerland
Dutch accelerator physicist who invented stochastic cooling, making antiproton beams dense enough to discover the W and Z bosons.
A Philips-trained engineer who joined CERN in 1956, van der Meer quietly designed beam diagnostics — including the beam-position monitors still standard today — before conceiving in 1968 the revolutionary idea that fluctuations in a beam's own signal could be amplified and fed back to squeeze its momentum spread. First demonstrated on the ISR, stochastic cooling let the Antiproton Accumulator supply enough p̄ for the SPS collider — and hence for the W and Z discoveries.
Nobel-winning work
Van der Meer shared the 1984 Nobel Prize for the technique that made the W and Z discoveries possible. Stochastic cooling samples the position of a particle beam at a pickup, amplifies the error signal and applies a correction at a kicker downstream; repeated millions of times per second, it shrinks the beam's phase-space volume as Liouville's theorem alone would forbid.
Applied to antiprotons — rare products of proton-target collisions — the method accumulated dense p̄ bunches whose injection into the SPS created the proton-antiproton collider. Without it, UA1's event samples of a few W and Z per week would have been impossible.
Workplaces: CERN
Netherlands