52nd Session of CERN Council

At the 52nd CERN Council Session in June the Directors General presented reports from the two CERN Laboratories.

W K Jentschke mentioned further evidence for neutral currents in neutrino experiments with the Gargamelle heavy liquid bubble chamber, evidence for the unification of the weak and electromagnetic interactions. Another example of neutrino-electron scattering has been seen and over two hundred events on nucleons are now confirmed. In addition, an experiment with a proton beam into the chamber has checked that the estimate of the background, which could result in other events being confused with neutral current events, is correct.

Steady progress in building the 400 GeV super proton synchrotron (SPS) in Lab II was reported by J B Adams. He emphasised the work on the machine tunnel. At the time of the Council Session, the “mole” had bored its way around 90% of the 7 km circumference of the machine, maintaining an accuracy of better than 5 cm compared to its planned position.

Everything remains on schedule for commissioning the accelerator in the second half of 1976.

• Compiled from texts on pp247–249.

Completion of the SPS tunnel

On 12 March 1973 the Robbins boring machine was ready, 50 metres underground, to start piercing the SPS tunnel, 4.8 metres in diameter, through the layer of molasse – a ring 6900 metres in circumference. On 31 July 1974 the “mole” finished the job, completing a major stage in the construction of the 400  GeV accelerator.

The machine worked with commendable efficiency, boring at an average rate of about 21 metres per day – faster than originally foreseen. Apart from rest days, there were four breaks, totalling eleven weeks out of the sixteen and a half months of operation.

• Compiled from texts on p248, pp251–252

Compiler's note

The SPS came into operation in May 1976. Designed to accelerate protons, in 1981 it became the world’s first proton–antiproton collider, enabling the discovery of the weak-interaction bosons, W and Z. This consolidated the unified electroweak theory and earned the 1984 Nobel Prize for Carlo Rubbia and Simon van der Meer. Today this venerable workhorse is again accelerating protons, as a go-between in CERN’s accelerator complex, taking 25 GeV beams from the PS up to 450 GeV for injection into the LHC.

Underpinning new particles and coveted prizes is the laboratory’s life-support system – electricity and water. Consumption depends on whether the machines are running or shut down for maintenance. Typically, the LHC operates between May and December, being switched off during the winter as an economy measure. In such a year, CERN consumes around 1.3 TWh of power, provided via a French substation in Prévessin, and about 4 Mm3 of water, most of it pumped out of Lake Geneva at Le Vengeron – enough water to run the iconic Jet d’Eau for about three months.