Data analysis techniques in high energy physics

Abstract

An account is given of the reduction and analysis of data from bubble chambers. Initially, the principles of operation and the important advances in the bubble chamber technique are briefly described. Since the discovery of the bubble chamber principle, chamber volumes have increased in two decades by a factor of 106. The development in the chambers themselves has been accompanied by a parallel development in the techniques used to analyse the data. The development of film measuring machines is then outlined and the construction and performance of some of these machines are discussed. In the late 1950's manual machines such as Franckenstein were highly automated and they were operating on-line to computers by the second half of the 1960's with program assistance and error detection. Fully automatic machines, proposed in the early 1960's, did not live up to their early promise. Evidently automatic event recognition is a very sophisticated task and the crude methods at present available require far too much computer time. Problems with precision CRT's were resolved in the mid 1960's, and their advantages over mechanical scanning systems have been successfully exploited. At the present time semi-automatic CRT machines such as POLLY are proving most successful. Specialized processor hardware such as BRUSH and SATR may eventually offer the solution to complete automation. The rest of the article describes the geometrical reconstruction, kinematical fitting and statistical analysis of bubble chamber events. The problems of geometrical reconstruction in the present generation of chambers caused by the use of wide angle photography are discussed. A description of the common methods of presenting bubble chamber data and some of the mathematical techniques used in the analysis are also given.