Number 64 (Story #3), January 20, 1992 by Phillip F. Schewe and Ben Stein THE TOP QUARK MASS must be at least 91 GeV/c2, according to the Fermilab collaboration working at the colossal CDF detector. Studying pairs of leptons issuing from high energy proton-antiproton collisions, the CDF team did not find evidence for the top, which is expected to exist by the Standard Model of particle interactions, but they could affix the new lower limit on the top's mass. The previous CDF lower limit, published in 1990, was 77 GeV/c2. (F. Abe et al., 27 January 1992 issue of Physical Review Letters; this article lists 268 authors from 21 institutions.)