Attempts to use accelerator mass spectrometry to detect fractionally charged particles in N ature

Abstract

The search for fractionally charged particles (FCP) in Nature is ultimately motivated by the belief that the fundamental constituents of the atomic nucleus are quarks, which have charge in integral units of 1/3 of the electronic charge. The reported observation of fractional charge in niobium by a group at Stanford University in 1981 has motivated many new efforts to detect FCP in the past few years. The techniques of accelerator mass spectrometry (AMS) have been successfully applied to this problem at several laboratories. The method generally involves the use of electrostatic analysis systems to separate the FCP from integrally charged ions, since the mass of the FCP is not known a priori . A variety of materials have been searched in these experiments and the most sensitive limits are at concentration levels of less than 10 -18 FCP per atom of host material.