Interactions of 1.0-, 2.0-, and 3-GeV Protons with Ag and Br in Nuclear Emulsion. II

Cross sections for star production and for emission of $\alpha$ particles, light fragments ($3<~Z<~6$), and ${\mathrm{Li}}^8$ nuclei are reported for interaction of high-energy protons with the heavy elements in Ilford K.0 nuclear emulsion. These cross sections increase rapidly between 1.0 and 2.0 GeV, and then they level off between 2 and 3 GeV. Those stars which are characterized by two dense tracks in approximately opposite directions have cross sections of 7±2, 30±7, and 50±10 mb at 1.0, 2.0, and 3 GeV, respectively. Arguments are presented which strongly support the idea that the two fragments are of roughly comparable mass and are both mainly in the region $A\approx 15-35$ with $Z\approx 7-17$. This view is compared with that of Gorichev, Lozhkin, and Perfilov according to which the two fragments are very different in mass, the lighter one being a fragment of $Z=4-9\mathrm{}$ and the heavier one a nuclear recoil.