A Fast Logic System for Geometrical Selection of Spark Chamber Triggers

A fast parallel logic system employing MECL II integrated circuits with a total analysis time of about 100 nsec was used to preselect elastic scattering events in a K-p scattering experiment. A ninety counter scintillation hodoscope arranged in banks of ten counters each allowed the selection of events on the basis of a) The presence of exactly two outgoing particles b) Coplanarity of outgoing particles with respect to the incoming beam c) Approximate agreement of outgoing angles with calculated kinematic requirements. About 3% of candidate events satisfied this set of restrictions and initiated spark chamber pulsing and data transfer to a computer.