Speaker
Description
In neutron polarization analysis studies changes of neutron beam polarization are observed, which are exclusively due to the interaction of the neutron spin with a sample studied. The interactions can be of two types: with nuclear spins and with magnetic fields inside the sample i.e. primarily between the nuclei. In NSE spectroscopy the behavior of the neutron beam polarization along neutron paths outside the sample is analyzed using special magnetic field configurations. In addition, the NSE configuration can also be specially adapted to the neutron spin changes inside the sample, in order to maintain its capability to analyze neutron energy changes in the scattering event on the sample. These configurations are different for samples of different magnetic behaviors such as paramagnetic, ferromagnetic, antiferromagnetic etc. In nonmagnetic samples, i.e. without strong internal magnetic fields between the nuclei, the standard NSE configuration operates unperturbed and also provides full polarization analyzed neutron scattering information at the same time as probing the quasielastic behavior. Actually, the polarization analysis information is always present in the standard raw data collection files at ILL, and even old data that have not been evaluated for polarization analysis can also be revisited and reevaluated for extracting the polarization information too, which was eventually not a point of interest at the time the data were taken. This revisiting feature could be of interest, for example in some polymer samples. The full, combined polarization and NSE quasielastic analysis method has been recently utilized for the study of intermediate length range correlations in water and heavy water over distances corresponding to 2 – 5 times the average intermolecular spacing.
