The first monitor measuring secondary beam particles (TBID - target beam instrumentation downstream) has been installed on 9 March 2006. This monitor is located in the small space available between the marble shielding downstream of the target and the magnetic horn.

TBID monitors are installed downstream of most SPS target stations. The monitor is based on the principle of secondary electron emission from thin foils, particularly well suited for measurements in very high intensity beams. For a correct operation of such monitors, a vacuum of better than 10^-4 mbar is necessary.

The basis structure of the CNGS - TBID has been recuperated from a spare monitor prepared for the former West Area. Due to the hostile environment downstream of the CNGS target which makes standard turbomolecular pumps or similar systems difficult to operate, a novel method for keeping the TBID monitor under vacuum has been developped. The system is based on a getter pump activated before installation of the TBID. Initial outgassing of the system will be pump by an ionisation pump. The details of this system have been described in a CERN-TS note.

(Photos: Ivo Wevers)