Losses and depolarization of ultracold neutrons on neutron guide and storage materials

Abstract : At Institut Laue-Langevin (ILL) and Paul Scherrer Institute (PSI), we have measured the losses and depolarization probabilities of ultracold neutrons on various materials: (i) nickel-molybdenum alloys with weight percentages of 82/18, 85/15, 88/12, 91/9, and 94/6 and natural nickel Ni100, (ii) nickel-vanadium NiV93/7, (iii) copper, and (iv) deuterated polystyrene (dPS). For the different samples, storage-time constants up to ∼ 460 s were obtained at room temperature. The corresponding loss parameters for ultracold neutrons, η , varied between 1.0 × 10 − 4 and 2.2 × 10 − 4 . All η values are in agreement with theory except for dPS, where anomalous losses at room temperature were established with four standard deviations. The depolarization probabilities per wall collision β measured with unprecedented sensitivity varied between 0.7 × 10 − 6 and 9.0 × 10 − 6 . Our depolarization result for copper differs from other experiments by 4.4 and 15.8 standard deviations. The β values of the paramagnetic NiMo alloys over molybdenum content show an increase of β with increasing Mo content. This is in disagreement with expectations from literature. Finally, ferromagnetic behavior of NiMo alloys at room temperature was found for molybdenum contents of 6.5 at.% or less and paramagnetic behavior for more than 8.7 at.%. This may contribute to solving an ambiguity in literature.
Document type :
Journal articles
Complete list of metadatas

Contributor : Inspire Hep <>
Submitted on : Thursday, November 23, 2017 - 10:50:26 AM
Last modification on : Thursday, July 18, 2019 - 5:18:48 PM

Links full text



V. Bondar, S. Chesnevskaya, M. Daum, B. Franke, P. Geltenbort, et al.. Losses and depolarization of ultracold neutrons on neutron guide and storage materials. Phys.Rev.C, 2017, 96 (3), pp.035205. ⟨10.1103/PhysRevC.96.035205⟩. ⟨hal-01645840⟩



Record views