Monte Carlo simulations of trapped ultracold neutrons in the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>UCN</mml:mi><mml:mi>τ</mml:mi></mml:mrow></mml:math> experiment

In the \mathrm{UCN}\ensuremath{\tau}experiment, ultracold neutrons (UCN) are confined by magnetic fields and the Earth's gravitational field. Field-trapping mitigates the problem of UCN loss on material surfaces, which caused the largest correction in prior neutron experiments using material bottles. However, the neutron dynamics in field traps differ qualitatively from those in material bottles. In the latter case, neutrons bounce off...