Ultracold neutron accumulation in a superfluid-helium converter with magnetic multipole reflector

摘要

We analyze accumulation of ultracold neutrons (UCN) in a superfluid-heliumconverter vessel surrounded by a magnetic multipole reflector. We solved thespin-dependent rate equation, employing formulas valid for adiabatic spintransport of trapped UCN in mechanical equilibrium. Results for saturation UCNdensities are obtained in dependence of order and strength of the multipolarfield. The addition of magnetic storage to neutron optical potentials canincrease the density and energy of the low field seeking UCN produced andserves to mitigate the effects of wall losses on the source performance. Italso can provide a highly polarized sample of UCN without need to polarize theneutron beam incident on the converter. This work was performed in preparationof the UCN source project SuperSUN at the ILL.