Search for fractionally charged particles in cosmic rays with the BESS spectrometer

Historically, there are been many searches for fractionally charged particles in the cosmic radiation. However, few searches have been performed near the top of the atmosphere. We performed a search for relativistic 23e charged particles in cosmic rays using data collected during four BESS balloon flights from 1997 to 2000 carried out in northern Canada. The data were analyzed by examining energy deposition in the time-of-flight scintillator hodoscopes. No candidate was found. We derive an upper limit of 4.5 × 10−7 (cm2 s sr)−1 for the flux of 23e charged particles, at the 90% confidence level.