IN16B, a sub-micro-eV energy resolution backscattering spectrometer with a very high count rate and wide dynamic range

The flux at the sample position is enhanced by a new 'quasi-ballistic' neutron guide and its focusing to a fast rotating Phase Space Transformation (PST) chopper at the end-of-guide position. The PST, together with a linear motor Doppler drive enables to double the energy transfer range at sub-microeV energy resolution. The vertical increase of the analyser surface together with a new vertically position sensitive multi-tube-detector will nearly double the count rate for the large angles. The background is optimized by placing the analysers and all flight path in vacuum and by using a background chopper.

The following yet incomplete list will with time be completed with new examples from IN16B.

• An ideal application for backscattering spectroscopy is rotational tunneling of molecular rotors (e.g. -CH₃,-NH₄). New developments in this field have arisen from combining neutron spectroscopy and molecular dynamics simulations. Tunneling in amorphous systems were first detected on IN16 as quasielastic broadening.
• Hyperfine splitting of some elements (e.g. Co, Nd, Ho, V,...) is another example for inelastic spectroscopy in the micro-eV energy range.
• Among the classical fields of application for quasielastic scattering are relaxation processes in glasses, H-diffusion in metals or proton and ionic conductors as well as diffusion of molecules confined in host matrices. Sometimes this research is related to fundamental studies for applications as energy materials or catalysis.
• Of wide interest is the study of local dynamics in complex materials like polymers, membranes and biological samples
• Some interest can be found in the study of spin dynamics of disordered magnetic materials.