Search for Fractionally Charged Particles

Abstract

We have performed a geophysical search for fractionally charged particles in seawater and rock samples. The samples were run through cation exchange columns to separate most of the material from particles of charge $\ifmmode\pm\else\textpm\fi{}\frac{2}{3}$ and $\ifmmode\pm\else\textpm\fi{}\frac{1}{3}$. The purified samples were converted into azides and evaporated in an electron gun, which accelerated the negatively charged particles to a solid-state detector. Quarks with charge $+\frac{2}{3} ({q}_{1})$ would probably evaporate from azides as (${q}_{1}+e$) and would thus have an effective charge of $\ensuremath{-}\frac{1}{3}$. The pulse-height spectra from the detector were scanned for peaks corresponding to particles of a charge between -1 and 0; no such particles were found. Limits on the concentration of ${q}_{1}$ quarks are \ensuremath{\lesssim}${10}^{\ensuremath{-}23}$ quarks/nucleon in the rock samples and \ensuremath{\lesssim}${10}^{\ensuremath{-}24}$ quarks/nucleon in the seawater samples. These limits depend, of course, on the assumptions concerning the chemical behavior of quarks made in the text.