Characterization of electroless nickel-phosphorus plating for ultracold-neutron storage

Abstract

Electroless nickel plating is an established industrial process that provides a robust and relatively low-cost coating suitable for transporting and storing ultracold neutrons (UCN). Using roughness measurements and UCN-storage experiments we characterized UCN guides made from polished aluminum or stainless-steel tubes plated by several vendors. All electroless nickel platings were similarly suited for UCN storage with an average loss probability per wall bounce of $2.8\cdot 10^{-4}$ to $4.1\cdot 10^{-4}$ for energies between 90 neV and 190 neV, or a ratio of imaginary to real Fermi potential $\eta$ of $1.7\cdot 10^{-4}$ to $3.3\cdot 10^{-4}$. Measurements at different elevations indicate that the energy dependence of UCN losses is well described by the imaginary Fermi potential. Some special considerations are required to avoid an increase in surface roughness during the plating process and hence a reduction in UCN transmission. Increased roughness had only a minor impact on storage properties. Based on these findings we chose a vendor to plate the UCN-production vessel that will contain the superfluid-helium converter for the new TRIUMF UltraCold Advanced Neutron (TUCAN) source, achieving acceptable UCN-storage properties with $\eta =3.5(5)\cdot 10^{-4}$.

arXiv comment8 pages, 7 figures

References in corpus (10)

• Performance of the upgraded ultracold neutron source at Los Alamos National Laboratory and its implication for a possible neutron electric dipole moment experiment
• First ultracold neutrons produced at TRIUMF
• Neutron optics of the PSI ultracold neutron source: characterization and simulation
• Pulsed UCN production using a Doppler shifter at J-PARC
• Optimizing neutron moderators for a spallation-driven ultracold-neutron source at TRIUMF
• Evaluation of commercial nickel-phosphorus coating for ultracold neutron guides using a pinhole bottling method
• PENTrack---a simulation tool for ultracold neutrons, protons, and electrons in complex electromagnetic fields and geometries
• Measurement of spin-flip probabilities for ultracold neutrons interacting with nickel phosphorus coated surfaces
• Characterization of a scintillating lithium glass ultra-cold neutron detector
• Characterization of the new Ultracold Neutron beamline at the LANL UCN facility

Cited by in corpus (2)

• A diffuse scattering model of ultracold neutrons on wavy surfaces
• Polarized cold-neutron reflectometry at JRR-3/MINE2 for the development of ultracold-neutron spin analyzers for a neutron EDM experiment at TRIUMF