Beam current transformer (BCT) for experiment WA1/2

In experiment WA1/2, a 400 GeV proton beam from the SPS was directed at a target, downstream of which a hadron line selected, in several narrow momentum bands, a beam of either pi+ and K+ or pi- and K-. These neutrino-parent particles, before entering a 292 m long decay tunnel, passed through a set of 2 BCTs of a design seen here. They measured the hadron intensity (10^10 to 10^11 particles/pulse) with a precision of the order of 1%. There were 2 of them, for enhanced precision and confidence. After the discovery of neutral currents in the Gargamelle-experiment, WA1/2 was the first follow-up, high-precision experiment (Z.Phys.C35, 443-452, 1987 and Z.Phys.C45, 361-379, 1990). See also 7706516X.