Crystal-Diffraction Method for Ultraprecision Neutron Spectrometry. Influence of the Temperature Stability and Vibration Level

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Yu.P. Braginets, Yu.V. Borisov, V.V. Voronin, M.V. Lasitsa, S.Yu. Semenikhin, V.V. Fedorov

A test setup for measuring the neutron electric charge using spin interferometry and the effect of the double-crystal focusing of neutrons upon Laue diffraction is described. It is shown that a considerable increase in the distance between the crystals (up to 1 m) is needed to improve the accuracy of neutron-charge measurements. This is a difficult task because the setup becomes sensitive to slight external influences (temperature, vibration, etc.). To determine the degree of these influences, temperature tests with combined (active and passive) thermal protection were carried out. It is shown that under conditions of the reactor hall with temperature fluctuations of several degrees, the experimental setup provides a temperature stability of the crystals no worse than 0.01 K and stability of the temperature differences for the crystals and between them at a level of ~0.005 K. Measurements of the vibration level in the area of the PF1b cold neutron beam at the ILL reactor (Grenoble, France) allow estimation of the rate of displacement of crystals relative to each other at a level of ~10^–3 cm/s. As follows from the data obtained, the angular resolution of the setup, without taking into account the influence of the imperfection of real crystals, can be at the level of 10^–3 of the Braggreflection width, which is ~0.001 arc-second.

Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques, 2020, Vol. 14, No. 1, pp. 163–168.

• https://link.springer.com/article/10.1134/S102745102002007X
• https://elibrary.ru/item.asp?id=42339803
• https://doi.org/10.31857/S1028096020020077
• https://doi.org/10.1134/S102745102002007X