The P326 (NA48/3) Gigatracker: Requirements and design concept

P326 aims at measuring the very rare decay at the CERN SPS. The Gigatracker should track every particle of the hadron beam at a rate of about 1 GHz with time resolution in the 100 ps range and good momentum and angle resolution. The calculated fluence in 100 days of data taking is comparable to the one expected in the inner layers of the silicon trackers in LHC experiments during 10 years of operation. The physics requirements on the Gigatracker performance are overviewed and the preliminary design concept is outlined.