Unassisted Analysis Of Bubble Chamber Events

Hardware and computer programs have been developed which allow bubble chamber events to be recognized and measured without manual assistance. All tracks in the three film images are digitized. Those track verticies which signify events are found, and the tracks are associated between views. Cost, precision and reliability are favorable in comparison to manual methods. The unassisted analysis of bubble chamber data has advantages not only as an economical means of converting these data into a meaningful numerical form, but also as a necessary step in the direction of putting such analysis online to the experiment. Modern techniques allow accelerators and bubble chambers to produce one photographic exposure per second over sustained intervals. This means that 300,000 sets of three "stereo-triad" film images can typically be obtained in a calendar week of chamber operation. An average of one event of interest is contained in each triad. Analysis by conventional means of a week's output from the bubble chamber consumes a thousand man-weeks of effort for scanning and measuring alone, just to find and convert to numerical form the data contained in the film images. Yet the statistical needs of current experiments often require two and three times this quantity of data in order to obtain significant results. Clearly there are compelling reasons to develop improved analysis procedures, from consideration of the labor cost as well as the urgent need to complete the experiment within a reasonably short time. A number of analysis systems (Ref. 1-7), have been developed in recent years which use computers to assist the human operators. Still another system (Ref.8),has come into being which measures some frames automatically, and calls for help only when problem events are detected. A substantial fraction of the events require such manual assistance. Therefore, both systems are limited by human response times. A factor of ten gained over conventional methods seems to be an upper limit; further gains are made difficult by the fact that the operator must have time to see, recognize and direct the measurement of each event whose analysis is given to him. Measurement costs have been decreased, although for obvious reasons, not in direct proportion to the reduction of manual effort. These systems represent significant advances in the technology of data acquisition, but they are severely limited by their inability to attain analysis rates commensurate with those of bubble chamber operation. Typically four to eighteen months are required to analyze the output of one week's chamber operation. Analysis of bubble chamber experiments within the real-time scale of chamber operation offers significant advantages to the experimenter. Not only can the data acquisition process be monitored so as to assure that technical failures do not weaken the usefulness of the gathered results, but also the planned experiment can be modified in response to informa-tion found in its early phases. However, experimental physics budgets are not able to support this step into real-time if it adds significantly to the analysis cost. The criteria for improved procedures are thus established; to move toward reliable real-time analysis while continuing to decrease the cost per event.© (1969) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.