Simulation of nonstationary storage of ultracold neutrons from aperiodic pulsed neutron source in neutron guides with an exit end reflector

Monte Carlo simulation is performed for nonstationary transport and storage of ultracold neutrons (UCN) in nonperfect curved vertical and horizontal neutron guides with a reflector at the exit end. It is shown that a significant part of UCN, reaching the end section of the neutron guide (30–50%) may be trapped in a small volume 1–2 l.