EMISSION OF CHARGED $Sigma$ + $pi$ FROM K$sup -$-PROTON CAPTURE IN NUCLEAR EMULSIONS

>100 two-prong stars with chsrged baryons and pi mesons only from K- capture in nuclear emulsions have been analyzed. 23 SIGMA /sup +/+ pi -, 30 SIGMA - + pi +, and 9 SIGMA /sup plus or minus / + pi /sup plus or minus events were compatible with captures on bound and free protons. A comparison between the expertmental and expected hyperon energy distribution, using a degenerate Fermi gas model of the nucleus, gives a best fit for an attractive real SIGMA -nuclear potential of 25 Mev. An average Coulomb potential of the capturing nucleus of 8 plus or minus 2 Mev is deduced. The fraction of zero prong SIGMA /sup -/stars is 0.66 plus or minus 0.10. The SIGMA /sup -/ mass is found to be m SIGMA /- = 1196.7 plus or minus 0.6 Mev from three K- captures on free protons. (auth)