The investigation of UCN interaction with the surface of beryllium and stainless steel by the new method based on the neutron induced γ-radiation analysis

It is not exactly clear, why the experimental values of the UCN storage time in the vessels made from any materials are always considerably shorter than that theoretically predicted. The new experimental approach was successful to study this problem for beryllium and stainless steel. It was found that the high hydrogen content is the main source of short storage time for beryllium UCN traps. Probability of losses per one collision with surface under different sample treatment steps were measured and the total cross-section of inelastic heating of UCN by hydrogen was estimated. Strong difference between surface and volume chemical structures of the stainless steel causes an increased capture of UCN.