A Search for Lightly Ionizing Particles with the MACRO Detector

A search for lightly ionizing particles has been performed with the MACRO detector. A specially designed field programmable gate array based system was used for triggering, and the data. analysis was performed on data. recorded with a custom 200 MHz waveform digitizer system. Many novel techniques were used in the data analysis, including a neural network for timing reconstruction. This search was sensitive to particles with charges between ⅕e and close to the charge of an electron. The detector is sensitive to particles with β of between approximately 0.25 and 1.0. Unlike previous searches both single track events and tracks buried within high multiplicity muon showers were examined. In a period of approximately one year no candidates were observed. Assuming an isotropic flux, for the single track sample this corresponds to a 90% C.L. upper flux limit in the region of 100% efficiency of ɸ ≤ 9.2 x 10-15cm-2sec-1sr-1.