SCI prototyping for the second level trigger system of the ATLAS experiment

SCI's ultra low latency and high bandwidth make it a possible candidate to solve the problem of interconnecting a large number of processors in order to filter data produced in high energy physics experiments. In particular, the article focuses on prototyping for the second level trigger system of the ATLAS experiment, at the European Laboratory for Particle Physics (CERN). After a brief introduction to the problem of real time data selection in HEP experiments, the article presents the definition, design, implementation and test of a low-level application programming interface (API) for SCI. Finally, the higher-level application software, the overall architecture of the system and their evolution are described. (17 refs).