Measurement of p̄p and p̄-nucleus annihilation cross sections at very low energy at LEAR

An experimental procedure for the measurement of the p̄p and p̄-nucleus total annihilation cross sections, at very low p̄ incident momenta (between 174 and 37 MeV/c), has been developed by the Obelix experiment at LEAR. The procedure is based on the ability in using gaseous targets at different pressures (from 10−4 to 3 bar absolute pressure) and in recording both the coordinates of the vertex and the time of the annihilation. In this work, a detailed description of this experimental method is presented.