180° Production of $p$, $d$, and $t$, and $p-p$ Correlation in $p$-Nucleus Collisions

The characteristic features of the energy distributions of the 180° -emitted protons, deuterons, and tritons from 0.6 to 400 GeV incident energy, the extremely weak angular dependence of single-particle inclusive cross sections in the backward directions, and the existence of forward-backward $\mathrm{pp}$ correlation are shown to be due to fragmentation of the effective target (that is, the system of nucleons in the target nucleus along the axis of the incident proton) in proton-nucleus collisions. Correlation effects in violent processes are also briefly discussed.