Observation of a universal charge-exchange dependence across rapidity gaps in 200-GeV/c. pi. /sup -/p interactions

Direct evidence is presented showing a universal decrease of charge exchange absolute value ..delta..Q +1 as a function of rapidity-gap length, independence of multiplicity and rapidity position within an event. The region over which charge exchange does occur (the ''charge-mobility length'') is 1.3 rapidity units. (AIP)