Reliability enhancement of the MNP23 magnet in the East Experimental Hall

The MNP23 magnet is installed in the East Experimental Hall, which is a part of the PS complex located at CERN in Meyrin. It is a very compact septum magnet used to distribute the beam to the different users in the T9 line. The magnet is installed in an area exposed to high levels of ionizing radiation, and is operated at extreme water pressure and flow rate: such conditions are responsible of recurrent failures which not only produce frequent stops of the facility, but also require interventions in radioactive areas and repair of very radioactive components. Since 1970 three different designs have been attempted, all resulting in a poor reliability. This paper reports about a new modification of the magnet which has been implemented in 2010 and should ensure, in principle, a definitive fix to the problems encountered so far.