Search for highly ionizing particles in e + e − collisions at s = 29 GeV

The results of the analysis of data taken in the continuation of a previously reported search for highly ionizing particles at PEP are presented. Assemblies consisting of Lexan and CR-39 plastic track detectors were exposed in two runs to integrated luminosities of 30 x 10/sup 36/ cm/sup -2/ and 150 x 10/sup 36/ cm/sup -2/. The search was sensitive to particles with magnetic charge 20e< or =g< or =200e or electric charge 3< or =Z< or =180. A combined (95% C.L.) upper limit on the production cross section of sigma<3.2 x 10/sup -38/ cm/sup 2/ is obtained, improving our previous limits by more than an order of magnitude.