The 2 m hydrogen bubble chamber With its magnet rolled back during a shut-down of the Proton Synchrotron in 1969, the body of the 2 m hydrogen bubble chamber becomes visible

The 2 metre hydrogen bubble chamber minus its magnet. The chamber was undergoing a series of modifications during the PS shutdown and for this the two halves of the magnet which normally hide the chamber, safety tanks, cooling pipes etc. were rolled back. The chamber joined the select band of 10 million picture takers on 6 September 1969. This figure had been reached in five years of operation.