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 were obtained at room temperature. The corresponding loss parameters for ultracold neutrons, , varied between and . All 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 measured with unprecedented sensitivity varied between and . Our depolarization result for copper differs from other experiments by 4.4 and 15.8 standard deviations. The values of the paramagnetic NiMo alloys over molybdenum content show an increase of 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.
15 More- Received 3 May 2017
DOI:https://doi.org/10.1103/PhysRevC.96.035205
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