Turbine Effect in an Experiment with Storage of Ultracold Neutrons

Abstract

When ultracold neutrons interact with moving surfaces, their energy can change (so-called turbine effect). In this case, both an increase and a decrease in the neutron energy are possible. In previous experiments with the capture of ultracold neutrons in a gravitational trap by rotating it, it was made to have the shape of a body of revolution, which was done specifically to avoid the turbine effect. In this paper, the authors consider an experiment with a rotating gravitational trap that does not have the shape of a body of revolution. The Monte Carlo method was used to simulate the turbine effect at different stages of the experiment. The transformation of the neutron spectrum over time is calculated as a function of the trap rotation speed. A possible systematic error in the measurement of the neutron lifetime due to the influence of the turbine effect is considered. Experimental parameters are obtained for which it is absent.