Search for lightly ionizing particles with the MACRO detector

Abstract

A search for lightly ionizing particles has been performed with the MACRO detector. This search was sensitive to particles with charges between $\frac{1}{5}e$ and close to the charge of an electron, with \ensuremath{\beta} 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 $\ensuremath{\Phi}<~9.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}15}{\mathrm{cm}}^{\ensuremath{-}2}{\mathrm{s}}^{\ensuremath{-}1}{\mathrm{sr}}^{\mathrm{\ensuremath{-}}1}.$