Zone Selection in Multiparameter Analysis

In many nuclear physics experiments, particularly those based on coincidence methods, the active descriptors are distributed over a relatively wide field. Associative storage has been suggested as a means of processing this type of data. However whether hardware or software is used, the cost per descriptor stored is many times higher for associative analysis than for conventional analysis. Costs may be reduced by taking advantage of the fact that in many experiments information occurs in groups or ´clusters´ of channels. This is achieved by the Zone Selection technique. The experimental field is divided into zones of adjacent channels and it is then only necessary to store the addresses of the active zones in the associative mode, the individual channels within the zone being defined conventionally. The overall system is then equivalent to conventional analysis with digital windows automatically set to the active zones while no storage space is used for inactive regions of the spectrum. A general formula has been derived for the performance of any system in relation to the zone and cluster sizes. The technique has been applied to both hardware and software systems.