Spin Echo Spectrometry Using Very Cold Neutrons

Concept of spin echo spectrometer on very cold neutrons (wavelengths λ ~ 10‒30 nm) to provide extra high resolution in energy transfer (ΔE ~ 10^–13 eV) has been proposed. Simultaneous measurements of spin echo signals at different wavelengths will be realized using broadband spin flippers in combination with Fourier-analysis of λ-spectrum. The application of very cold neutrons should extend the spin echo time diapason radically, t ~ 10^–12‒10^–3 s. This promises to open a set of novel scientific areas including the spectroscopy of chemical reactions and catalytic processes, conformational transitions in polymers and biological molecules, dynamic modes in carbon structures (fullerenes, nanotubes, graphenes) at scales from few nanometers to microns. Presently, the development of NSE-spectrometer on VCN becomes relevant since the project of ultra cold neutron source at WWR-M reactor (PNPI) is in progress.