Improved instrument for the determination of the neutron electric charge

Abstract We present an improved instrument for the determination of the neutron electric charge with ultracold neutrons. Several technical upgrades with respect to a former experiment will be discussed in detail. As a first test, we applied the apparatus to investigate the influence of gravitational attraction by means of a massive block of lead. The calculated sensitivity for a charge measurement is δ q n ≈ 2.14 × 10 − 20 e / day . Planned modifications increasing the sensitivity up to δ q n ≈ 1.34 × 10 − 21 e / day are demonstrated.