Number 113 (Story #1), February 3, 1993 by Phillip F. Schewe and Ben Stein THE SHAPE OF PARTICLE JETS produced in high-energy proton-antiproton collisions at Fermilab is determined largely by the radiation of gluons. Collisions in which the outgoing particles have a large momentum perpendicular to the beam axis are believed to come about by the scattering of a single quark inside the proton with a single quark inside the antiproton. The scattered quarks will then convert some of their energy into new particles; sometimes the particles emerge in a conelike spray or jet. A study of 100-GeV jets, the highest-energy jets ever seen in a particle physics experiment, shows that as expected the likelihood of the scattered quark emitting a gluon goes up at higher energies and that the shape of the ensuing jet (the width of the cone) depends on the opening angle between the quark and gluon. (CDF collaboration; F. Abe et al., 8 Feb. 1993 Physical Review Letters.)