Measurement of spin-flip probabilities for ultracold neutrons interacting with nickel phosphorus coated surfaces

摘要

We report a measurement of the spin-flip probabilities for ultracold neutrons interacting with surfaces coated with nickel phosphorus. For 50 μm thick nickel phosphorus coated on stainless steel, the spin-flip probability per bounce was found to be β_(NiP on SS) = (3.3_(-5.6)~(+1.8)) × 10~(-6). For 50 μm thick nickel phosphorus coated on aluminum, the spin-flip probability per bounce was found to be β_(NiP on Al) = (3.6_(-5.9)~(+2.1)) × 10~(-6). For the copper guide used as reference, the spin flip probability per bounce was found to be β_(Cu) = (6.7_(-2.5)~(+5.0)) × 10~(-6). The results on the nickel phosphorus-coated surfaces may be interpreted as upper limits, yielding β_(NiP on SS) ＜ 6.2 × 10~(-6) (90% C.L.) and β_(NiP on Al) ＜ 7.0 × 10~(-6) (90% C.L.) for 50 μm thick nickel phosphorus coated on stainless steel and 50 μm thick nickel phosphorus coated on aluminum, respectively. Nickel phosphorus coated stainless steel or aluminum provides a solution when low-cost, mechanically robust, and non-depolarizing UCN guides with a high Fermi potential are needed.