Wire Arrays Vs Vidicons: a Comparison of Large Wire Arrays with Optical Spark Chambers Using Vidicon Readout

Digitized spark-chamber systems using wire arrays are being used for increas­ ingly complex types of events; their chief virtue is the provision of "on-line II informa­ tion on the progre ss of the experiment, which we inte rpret as rapid enough to aIIow the results obtained to influence the future course of the experiment. Such on-line operation can also be obtained by several other methods for digitizing the data and introducing it into a computer. notably wire arrays. In particular, comparisons are made of the properties of wire arrays with a digitizing system in which visual spark chambers are viewed by vidicon television pickup tubes, whose output is immediately digitized for either tape storage or input to a computer. Such TV pickup systems have greater flexibility, require fewer special data storage provisions, automatically pro­ vide for indefinitely large numbers of tracks and track samplings and data redundancy, and fewer modifications for different experiments than wire arrays. In view of ex­ pected cost variations with size, it is likely that for sufficiently large systems, wire array readout wiII cost more than vidicon readout, in addition to being less flexible. Vidicon digitization is clearly preferable when many samplings are required, as in gamma-ray shower-detecting chambers. 1. ON-LINE OPERATION WITH WIRE ARRAY SPARK CHAMBERS Experiments done with spark chambers in the last five years or so show a trend toward two principal systems of operation. On the one hand are wire-array systems, with the data recorded and stored in digital form, suitable for immediate (on-line) processing. On the other hand are the visual chamber systems, with film recording, frequently including large magnets, and successfuIIy competing with bubble chambers in the recording and analysis of complex events. While both types of systems have been highly successful in their respective spheres, it is clear from recent developments that the wire-array system is steadily expanding its sphere of operation. Current wire-array systems have two major