GeV/c proton beam is extracted from the SPS in 10.5 microsecond short pulses of 2.4x1013
protons per pulse. The proton beam is transported through the transfer line TT41 to the CNGS target
T40. The target consists of a series of graphite rods, which are cooled by a recirculated
helium flow. Secondary pions and kaons of positive charge produced in the target are
focused into a parallel beam by a system of two pulsed magnetic lenses, called
horn and reflector. A 1 km
long evacuated decay pipe allows the pions and kaons to decay into their daughter
particles - of interest here is mainly the decay into muon-neutrinos and muons. The
remaining hadrons (protons, pions, kaons) are absorbed in an iron beam dump with a
graphite core. The muons are monitored in two sets of detectors downstream of the dump.
Further downstream, the muons are absorbed in the rock while the neutrinos continue their
travel towards Gran Sasso.