Nimrod (National Institute Machine Radiating on Downs, "the Mighty Hunter" Nimrod ; name attributed to W. Galbraith) was a 7 GeV proton synchrotron operating in the Rutherford Appleton Laboratory in the United Kingdom between 1964 and 1978. Nimrod delivered its last particles at 17:00 hrs on 6 June 1978. Although roughly contemporary with the CERN PS its conservative design used the "weak focussing" principle instead of the much more cost-effective "strong-focussing" technique, which would have enabled a machine of the same cost to reach much higher energies.