STUDY OF SOURCE SIZE IN P-(P)OVER-BAR COLLISIONS AT ROOT-S = 1.8 TEV USING PION INTERFEROMETRY

Experiment E735 collected data for approximately 10(7) interactions at the CO intersection of the Fermilab ppBAR collider with square-root s BAR = 1. 8 TeV. The Bose-Einstein correlations between pairs of identi cal pions were measured in a limited aperture spectrometer and used to estimate the size and lifetime of the source. The aperture shape limi ted the sensitivity primarily to the source dimension R along the inci dent ppBAR direction. Both this dimension and the lifetime appear to d epend strongly on pion multiplicity. Efforts were also made to obtain some information on the transverse source size, energy density, and th e dependence of source size and strength on dipion momentum. Fits to t he entire data sample yielded a value R = 1.06+/-0.07 fm for the avera ge source dimension and a value tau = 0.74+/-0.06 fm for the average s ource lifetime with [dN(c)/deta] = 14.4.