Measurement of the Summed Residual Projectile Mass in Relativistic Heavy-Ion Collisions

Measurements of the summed mass of projectile fragments, $M_s=\Sigma M_{\mathrm{pf}}$, are reported for 2.1-GeV/nucleon ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ + C and ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ + Mo. Unlike previous measurements of cross sections for individual projectile fragments, these measurements are quite sensitive to the size of the target nucleus. The distribution of summed residual projectile mass, $M_s$, provides the first conclusive evidence of the validity of the geometrical "abrasion" model of relativistic heavy-ion collisions.