Spin-flip loss in magnetic traps for ultracold neutrons

A particle with spin and magnetic-dipole moment can be trapped in certain suitable magnetic-field configurations only as long as its spin remains aligned with the field direction as it moves through the trap. Here, we extend earlier analyses of spin-flip probabilities, which lead to storage loss for ultracold neutrons, and present arguments indicating that some of the earlier results should be multiplied by a factor of two.