1. Institute of Macromolecular Compounds, Russian Academy of Sciences St. Petersburg Russia
2. Petersburg Nuclear Physics Institute named by B.P. Konstantinov of National Research Centre “Kurchatov Institute” Gatchina Russia
3. Frank Laboratory of Neutron Physics Joint Institute for Nuclear Research Dubna Russia
4. Moscow Institute of Physics and Technology Dolgoprudny Russia
5. Laboratoire Léon Brillouin UMR12 CEA‐CNRS CEA Saclay Gif sur Yvette Cedex France