OPTIMIZATION OF THE CHOPPER SYSTEM FOR THE COLD-NEUTRON TIME-OF-FLIGHT SPECTROMETER NEAT AT THE HMI, BERLIN

The instrument parameters governing intensity and energy resolution of a multidisk chopper spectrometer having been defined, a chopper system configuration must be found that ensures "true" monochromacy of the pulsed beam, i.e. avoidance of pulses with unwanted wavelengths. It is shown how a solution is obtained for the desired ranges of incident neutron wavelength and instrument energy resolution, taking into account the boundary conditions given in the case of the spectrometer NEAT at HMI, Berlin.