The equivalence of the gravitational and inertial mass of the neutron

Abstract A comparison of the neutron scattering length of carbon evaluated from a high precision total cross section measurement and the scattering length as measured with the neutron gravity refractometer leads to the most accurate determination of the equivalence factor γ between the gravitational and inertial mass for the neutron γ = 1.00038∓0.00025. Using all available data on scattering lengths and taking into account all systematic errors one obtains γ = 1.00011∓0.00017. The relevance of this result to the search for a composition dependent fifth force and possible new experiments are discussed.