Parallel arrays of digital signal processors as central decision elements for upper level triggers in high energy physics experiments

For tracking devices and calorimeters, the conflicting trends toward higher luminosity and improved background rejection have prompted the use of a hierarchical, multilevel trigger logic: the upper levels are usually devoted to ´physical´ background rejection and event flagging, as opposed to the lower level logic, mostly dealing with ´dull´ background at high rate. For the higher trigger levels, depending on the different machine and detector configurations, it is sometimes possible to design the ´detector data box´ as a programmable device, with increased flexibility and efficiency, and to use large arrays of digital signal processors working in parallel, giving excellent data throughputs inexpensively, provided that fast and efficient software algorithms can be implemented. A flexible and powerful scheme of this type is described, for two different experiments: the forward electromagnetic calorimeter of the DELPHI experiments at LEP (CERN), and the straw tube chamber of the E760 experiment at the antiproton accumulator at Fermilab.<>