coils which generated a field of 1.7 T and the whole apparatus weighted more than 700 tons. The expansion system of the 2 m bubble chamber allowed for multiple expansions during one PS pulse, which resulted in three event photos per beam pulse.

A 10 GeV/c K^- beam was required to produce the ?^- suggested by Murray Gell-Mann on his SU(3) theory. Hence, in 1965 a RF separated beam was added in order to obtain a separated K^-