Continued search for superheavy elements produced by secondary reactions of 24 GeV protons on uranium

A search was made for superheavy elements possibly produced by secondary reactions of 24 GeV protons in a thick uranium target. Chemical separation methods based on coprecipitation and liquid-liquid extraction as well as fission fragment detection techniques using solid state detectors (mica, plastic) were applied to the investigation. Am upper limit for the production cross section of superheavy elements of about 10-39cm2 is estimated, thus giving no evidence for their formation in such a reaction system. (author)