Prospects for measuring the gravitational free-fall of antihydrogen with emulsion detectors

The main goal of the AEgIS experiment at CERN is to test the weak equivalence principle for antimatter. AEgIS will measure the free-fall of an antihydrogen beam traversing a moiré deflectometer. The goal is to determine the gravitational acceleration g with an initial relative accuracy of 1% by using an emulsion detector combined with a silicon μ-strip detector to measure the time of flight. Nuclear emulsions can measure the annihilation vertex of antihydrogen atoms with a precision of ∼1–2 μm r.m.s. We present here results for emulsion detectors operated in vacuum using low energy antiprotons from the CERN antiproton decelerator. We compare with Monte Carlo simulations, and discuss the impact on the AEgIS project.