The Fast Track Trigger at the H1 experiment design concepts and algorithms

The H1 Collaboration has built a new Fast Track Trigger which performs a full reconstruction of charged particles in a high multiplicity environment. At the first trigger level ( 2.3 μ s ) coarse tracks are reconstructed in two dimensions whereas at the second level ( 23 μ s ) all tracks are reconstructed with high precision in all three dimensions. This allows to identify particle resonances at the third trigger level ( ≲ 100 μ s ) . The conceptual design and the implementation of the fast track finding algorithms are discussed. First results from the 2005 running period are presented.