We present antiproton invariant multiplicities from Experiment 941 using 12 and 19 GeV/c proton beams incident upon targets of Pb, Cu and Be. Since we are currently unable to calculate antiproton yields in this regime from first principles, we must rely on empirical data in order to answer questions involving antibaryon production at these energies. Typically, the motivation for studying this topic using proton-nucleus (p-A) collisions is to shed light on antiproton production in the more complicated collisions between heavy nuclei (A-A). For this reason, this thesis will use the measured target dependence to illuminate issues relating to annihilation of antiprotons in the nuclear medium. It is found that, at 19 GeV/c beam momentum, the ratio of the antiproton invariant multiplicities in lead divided by those in beryllium is less than one and suggests strong antiproton annihilation in the lead target. Furthermore, the target dependence does not disappear as the antiproton's relative momentum with respect to the nucleus increases, which may suggest that the antiproton often rescatters without annihilating in the heavier target. A simple Glauber model is employed to quantify the absorption in the nucleus. In addition, comparisons will be made with the antiproton production in E941's predecessor experiment, E864. The energy scaling observed by E941 will assist in the comparison of our data to E864 and other experiments.