Instrumentation for measurement of in-flight annihilations of 130 keV antiprotons on thin target foils

We describe the instrumentation for an experiment to measure the cross sections of antiprotons with kinetic energies of 130 +/- 10 keV annihilating on carbon, palladium, and platinum target foils of sub 100 nm thicknesses. A 120 ns long pulsed beam containing 10(5)-10(6) antiprotons was allowed to traverse the foils, and the signal annihilations that resulted from this were isolated using a time-of-flight method. Backgrounds arose from Rutherford scattering of the antiprotons off the target foils, their annihilations in the target chamber walls, and pi -> mu -> e decay of the charged pions that emerged from the annihilations. Some antiprotons slowed down and annihilated in the contamination on the target surfaces. This reduced the signal-to-background ratio of the measurement.