Progress report of the High Energy Physics Group of the Department of Nuclear Physics, University of Helsinki

Experimental research of high energy particle interactions has been continued in 1975 in the Department of Nuclear Physics. Analysis of the following experiments has been in progress: 1) 19 GeV/c pp- experiment in the CERN 2 m bubble chamber. Strange particle production (pp to K/sup 0/X, K/sup 0/K/sup 0/X, Lambda X; pp to p Lambda K/sup + /) and many particle processes have been further investigated. 2) 19 GeV/c pd-experiment in the CERN 2 m bubble chamber. Data processing has been continued, isospin analysis of the reactions NN to NN pi has been performed, two pion production processes have been investigated. 3) 23 GeV/c pp-experiment in the JINR 2 m bubble chamber at the Serpuhov accelerator. New pictures were taken, data processing has been continued. Topological cross sections have been determined. 4) 12 GeV/c pp-experiment in the CERN 2 m bubble chamber. Preparations have been made for some new experiments. (0 refs).