Preliminary study of a topological trigger device for cosmic-ray detectors

In view of implementing a topological trigger criterion in cosmic-ray detec tors for efficient selection of required events a preliminary test has been done with a scintillating-fibre hodoscope using a position-sensitive photo multiplier. A space resolution of similar to 0.6 mm in sigma with a detecti on efficiency > 97% has been obtained for charged particles of 5 GeV/c pass ing through 2 x 2 mm squared fibres. A custom-made discriminator, suppressi ng the cross-talk between adjacent fibres, allowed a better definition of t rack position even at high incident angles compared to the simple threshold discriminators. Simplicity as well as reliability of the prototype allow u s to foresee a topological trigger device incorporated in different type of detectors, such as cosmic gamma or electron telescopes, solar neutron dete ctors and so on. (C) 1999 Elsevier Science B.V, All rights reserved.