The ASACUSA (Atomic Spectroscopy And Collisions Using Slow Antipro- tons) collaboration of CERN is currently attempting to measure the antiproton-nucleus in-flight annihilation cross sections on thin target foils of C, Pd, and Pt at 130 keV of kinetic energy. The low-energy antiprotons were supplied by the Antiproton Decelera- tor (AD) and a radio-frequency quadrupole decelerator. For this measurement, a beam profile monitor based on secondary electron emission was developed. Data from this monitor was used to ensure that antiprotons were precisely tuned to the position of an 80- mm-diameter experimental target, by measuring the spatial profile of 200-ns-long beam pulses containing 10 5 10 6 antiprotons with an active area of 40 mm 40 mm and a spa- tial resolution of 4 mm. By using this monitor, we succeeded in finely tuning antiproton beams on the target, and observed some annihilation events originating from the target.