MULTI-PION CORRELATIONS IN 2-PION INTERFEROMETRY

The influence of multi-pion correlations on two-pion interferometry an alyses in multi-pion events can be expressed as the ratio of a multi-p ion correlation factor for the sample of like-pion pairs to a residual correlation factor for the reference sample. Although these two corre lation factors can partially cancel each other in data analyses, the d ifference between the two factors in the low relative momentum region is so large that the distortion from multi-pion interference becomes a serious problem when the pion source has a small radius and the pion multiplicity is high. The distributions of the multi-pion correlation factor C(n-2)(q)BAR offers a good sensitivity to multi-pion correlatio n effects. Analyses of the multi-pion correlation factor for two Beval ac streamer chamber data samples of 2.1 A GeV Ne + Pb and 1.8 A GeV Ar + Pb collisions show that the multi-pion correlation effect in the fo rmer sample is greater than that in the latter.